Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Joseph Anderson]

Hello Richard,

I was going to pipe up with very similar comments of my own... particularly as 
my creative work often uses close mic material recorded with the Soundfield mic.

I've recently compared some of these close mic materials I've recorded with the 
Soundfield and then transcoded to binaural via HRIR filters with 'in ear' close 
mic binaural recorded material. Both sets of recordings sounded 'very near'.

Additionally, it isn't very difficulty to synthesise proximity in FOA and get 
convincing results. See BLaH Appendix 2 (eqn 49):

E. Benjamin, R. Lee, and A. Heller, “Is My Decoder Ambisonic?,” in Proceedings 
of the 125th Audio Engineering Society Convention, San Francisco, 2008.


There's some other things you can do with image spreading a la Gerzon to 
increase the size of the image, too:

M. A. Gerzon, “Signal Processing for Simulating Realistic Stereo Images,” 
Preprint 3423, 92nd Audio Engineering Society Convention, San Francisco, 1992.


Combining image spreading w/ proximity can give a convincing sense of nearness. 
BTW, Andrés Cabrera has put together various spreading examples here:


A. Cabrera, “Pseudo-stereo Techniques: Csound Implementations,” CSOUND JOURNAL: 
Issue 14, 02-Jan-2011. [Online]. Available: 
http://www.csounds.com/journal/issue14/PseudoStereo.html. [Accessed: 
24-Jan-2011].


--
J Anderson



On 21 Jul 2011, at 1:45 pm, Richard Lee wrote:

>> It is true that 1st order ambisonics doesn't consider distance, with all 
> sources being reproduced at the distance of the speakers,
> .
>> synthesis, the ambisonic encoding equations do not include distance,
> 
> Both of these are untrue.
> 
> For the second, see the Appendix of BLaH3 "Is my decoder Ambisonic?" Heller 
> et al, AES San Francisco, 2008
> 
> There are two convenient proofs of the fallacy of the first.
> 
> While making a normal recording, creep silently up to your TetraMic or 
> Soundfield and whisper into it.
> 
> When you play this back to an unsuspecting victim seated in the centre of a 
> simple Classic Ambisonic rig, he will flinch.  He certainly doesn't hear 
> you at the radius of the speakers.
> 
> The other 'proof' is the B-format motorcycle that Soundfield have played at 
> nauseum at various shows.  Ambisonic myth has it that this was recorded by 
> the young Dr. Peter Lennox on Grand Vizier Malham's modified Calrec 
> Soundfield Mk 3A while the Vizier was away on a diplomatic visit to the   
> Great Turtle that Supports the Universe.  This mike was one of the first to 
> have IMHO, the proper EQ which allow a Soundfield to implement the correct 
> Ambisonic Encoding Eqns in the Appendix of BLaH3.
> 
> BTW, real human distance perception is TERRIBLE under anechoic conditions 
> cos waveform curvature is about the only thing left.  Those of you 
> investigating distance perception, please take note.
> 
> And you need a proper Classic Ambi decoder as defined by MAG and BLaH3 with 
> NFC.
> _
> 
> Why does this work?
> 
> At LF, simple 1st order Ambisonics with NFC IS a wavefield / soundfield 
> reconstruction system.
> 
> Then there's the snake oil in Calrec Soundfields, hand squeezed from solid 
> Unobtainium by Yorkshire virgins ...  Shaddup Lee!  Just Shaddup!
> 
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[Sursound] Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Dave Hunt]

Hi,


Date: Mon, 25 Jul 2011 08:24:55 -
From: Richard Lee 


Mr. Hunt, I hope Sampo & Fons have been sufficiently enlightening.  A
Classic Ambi rig or soundfield mike has no concept of a "unit circle".
 They record & present distance as presented to them.  The mike cos
Helmholtz etc and the Classic Ambi rig with tricks like NFC.  Even  
simple

1st order Classic Ambi rigs with NFC do a good job at plane wave
reconstruction at LF.


Both have been exemplary in their clarity, unlike myself.

I was so involved in thinking about what I was trying to say, and the  
relationship between Distance Compensation in a decoder and Near  
Field Compensation in NFC. that I didn't re-read what I'd written  
objectively enough before sending something with so many errors. I  
apologise, though the result has been very interesting.


The Distance Compensation (aka NFC, and not the shelf filters)  
attempts to correct for the loudspeakers not producing plane waves at  
the listener.


True the "Classic Ambi rig or soundfield mike . record & present  
distance as presented to them". The concept of a 'unit circle' only  
appears in the encoding equations, which describe how to 'pan' mono  
sources to produce B-Format signals. When you try to include distance  
in these there is a different behaviour outside the radius of the  
speakers, than inside. Direction is determined by coordinates limited  
to being inside the unit circle, whereas distance (and its effects on  
amplitude, time of arrival, and changes in reflections and  
reverberation) must use unlimited coordinates. Then it is useful to  
consider the radius of the speaker rig as unity, and all distances as  
being relative to that.


It has ben suggested that W = S(1 - 0.293(sq(x) + sq(y) + sq(z)),  
where S is source amplitude, be used to increase W to compensate for  
X,Y & Z tending to zero and perceived loudness decreasing instead of  
increasing with proximity. Again this is only applicable inside the  
'unit circle'. This is possibly only to be used if there is no other  
amplitude/distance law in operation.


The term NFC can be used in two different contexts: decoding, as in  
your above paragraph, and encoding, as in NFC-HOA, though that would  
also seem to include the decoding.


For a synthetic source to replicate this serendipitious situation,  
you have

to

1)	Add proximity for close sources or motorcyles as the Encoding  
Eqns in
Appendix of "Is my Decoder Ambisonic?"  This is the most important  
(only)

cue available for close sources in anechoic conditions


Agreed, but quantifiable only relatively i.e. for moving sources. For  
an unknown static source it tells you very little.


2)	Add a suitable reverb pattern as MAG's "Distance Panners".  You  
need to

do this not cos 1) dun wuk but cos real life distance perception is
TERRIBLE under anechoic conditions.  Ambisonics is probably the  
best "I am
there" system cos it's isotropic nature reproduces reverb and other  
diffuse
fields 'accurately'.  This was one of MAG's obsessions, even with  
stereo.


Anechoic conditions are fairly rare, and reverberant conditions  
common, especially in urban societies. More reverberation, or rather  
the variation in the ratio of direct to reverberant sound levels,  
suggests greater distance, but again it is only relative, and the  
nature and level of the reverberation is not simply related to source  
distance.


Reverberation is also used compositionally, to suggest distance, for  
effect, and to unite disparate sources in a common 'acoustic'.


3)	For very far souces, you might want to add HF absorption etc but  
this is

probably out of the realm of the sources you want to simulate.


As you say, HF absorption is only perceptible at large distances, and  
again is only relative.


Another factor is time of arrival of sound from a distant source, not  
directly perceptible unless accompanied by a visual event, or a  
source which is travelling towards or away from you, the Doppler  
effect.  It can be almost deleterious to model this, though it is  
commonly experienced.


Ciao,

Dave Hunt

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[Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Richard Lee]

There's loadsa good stuff being discussed here.  If I can comment on just 
one or two 

> When listening to this through a speaker rig, we hear this boost and tend 
to interpret it as meaning the sound is close especially in a dry acoustic 
with a Greene-Lee head brace etc., etc.,. However, surely (unless I am 
being more dense than usual tonight) this is a learnt response based on the 
behaviour we have heard from directional mics? After all, taken 
individually, at those sort of frequencies our ears are essentially 
omnidirectional and not subject to bass boost (to anything like the same 
degree).

You can test this.  Blindfolded your victim, creep up to him silently & 
whisper in one ear.  He will report significant proximity effect.  Eric, 
Duda & Marten will explain this happens cos our lugholes are spaced and 
form a crude (?) left/right velocity sensor.


Robert, Guru Fons has explained with his usual precision some of the 
limitations of the soundfield.  The important question, however, is, "what 
effect does all this have on the listener in the middle of a Classic Ambi 
system?".  The answer to both the "whisper in your TetraMic/Soundfield" and 
motorcycle examples is "closeness is exaggerated."

If you've got any Soundfield or TetraMic recordings where you've had to 
place the mike near or surrounded by the audience, the chap unwrapping 
sweets, rustling his programme or coughing always sounds as though he is 
directly next to the mike.


Mr. Hunt, I hope Sampo & Fons have been sufficiently enlightening.  A 
Classic Ambi rig or soundfield mike has no concept of a "unit circle". 
 They record & present distance as presented to them.  The mike cos 
Helmholtz etc and the Classic Ambi rig with tricks like NFC.  Even simple 
1st order Classic Ambi rigs with NFC do a good job at plane wave 
reconstruction at LF.

For a synthetic source to replicate this serendipitious situation, you have 
to

1)  Add proximity for close sources or motorcyles as the Encoding Eqns in 
Appendix of "Is my Decoder Ambisonic?"  This is the most important (only) 
cue available for close sources in anechoic conditions
2)  Add a suitable reverb pattern as MAG's "Distance Panners".  You need to 
do this not cos 1) dun wuk but cos real life distance perception is 
TERRIBLE under anechoic conditions.  Ambisonics is probably the best "I am 
there" system cos it's isotropic nature reproduces reverb and other diffuse 
fields 'accurately'.  This was one of MAG's obsessions, even with stereo.

3)  For very far souces, you might want to add HF absorption etc but this 
is 
probably out of the realm of the sources you want to simulate.


On heretical NFC HOA, there is a far simpler encoding system which avoids 
overload at LF and doesn't assume any speaker rig.  ie pure encoding.  This 
is to treat encoding as you would if you were designing a HOA mike.

For this, you MUST roll-off the LF at higher orders cos S/N.  This 
conveniently avoids the LF overload too.  But in any real playback 
situation, you only need HOA at HF so you don't actually lose much useful 
info.  All you have to do is to ensure the phase response of your LF 
roll-off is replicated by appropriate all-pass networks in the lower 
orders.  There's no need to even specify the LF roll-offs.

Building NFC into encoding (ie NFC HOA) should be a de-pinnaeable offense. 
 Keep encoding & decoding separate & clean please..

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Sampo Syreeni]

On 2011-07-25, Sampo Syreeni wrote:

Especially because, as you pointed out for quadrupoles, the 
sensitivity goes up exponentially.


Actually to be more exact, isn't the increase something like quadratic 
in order?

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Sampo Syreeni]

On 2011-07-24, Eric Benjamin wrote:

We can model the W output as being composed of a zeroth order 
(monopole) component plus a quadrapole component, which is frequency 
dependant. A quadrapole has a squared proximity effect, so for very 
close sources the proximity effect due to the quadrapole becomes 
significant relative to the desired zeroth order output. Not something 
that one would expect from an omni microphone!


Yes, and that tendency won't easily go down even for the higher 
harmonics. The nice thing about the Gaussian quadrature design of the 
classical, tetrahedral SF designs is that at it's pretty robust, and at 
least you can cancel out any first order, usually dominant bleeding into 
W in the following compensation circuit. Since you're capturing it, you 
can subtract it in a frequency selective fashion when going from A 
format to B format.


But if your array geometry is responsive to any higher harmonics and 
you're not capturing them, the folding is irreversible, and it gets 
worse as the higher components of the field become stronger. Thus, for 
something like flies recorded at less than an inch, I wouldn't be 
surprised if some of the significant directional aliasing terms would 
reach upto 6-8th order. Especially because, as you pointed out for 
quadrupoles, the sensitivity goes up exponentially.

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Eric Benjamin]

Sampo Syreeni wrote:
> the problem is squarely in that the higher order components can't be fully 
>suppressed

Exactly.  We can model the W output as being composed of a zeroth order 
(monopole) component plus a quadrapole component, which is frequency 
dependant.  
A quadrapole has a squared proximity effect, so for very close sources the 
proximity effect due to the quadrapole becomes significant relative to the 
desired zeroth order output.  Not something that one would expect from an omni 
microphone!


- Original Message 
From: Sampo Syreeni 
To: Surround Sound discussion group 
Sent: Sun, July 24, 2011 9:40:39 AM
Subject: Re: [Sursound] the recent 2-channel 3D sound formats and their 
viability for actual 360 degree sound

On 2011-07-24, Fons Adriaensen wrote:

> In a normal SF mic the effect could become significant if the distance 
> between 
>the capsules is a non-trivial fraction of the source distance AND of the 
>wavelength, so not really at low F.

Does that really matter, though? I mean, by definition XYZ contain particle 
velocity (or time integrated pressure gradient, whichever you prefer). With a 
near source, that already ought to show the proximity effect as long as the mic 
does anything remotely ambisonic. How it was built doesn't really seem to 
affect 
the results at this level.

So looked at from another angle, most of the phase differences that Robert 
pointed to, whether because of the directivity of the capsules or because of 
the 
capsule spacing plus the following corrective filter, actually ought to be 
there. Otherwise the mic wouldn't be measuring velocity as at should. So in 
fact 
the problem is squarely in that the higher order components can't be fully 
suppressed, but fold into the mix.
-- Sampo Syreeni, aka decoy - de...@iki.fi, http://decoy.iki.fi/front
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Eric Benjamin]

Robert Greene wrote:
> there are VERY serious problems of other kinds with using it at the kinds of 
>distances 
>
> (fractions of a meter less than 1/2 , much less often enough) where proximity
> effect becomes really major.

That is indeed true, except perhaps for the label of "Very".

I first noticed this in making measurements of soundfield microphones, not in 
analysis.  My measurement of the 'W' response showed proximity effect.  I 
believe that there are two reasons for this, both having to do with 
non-coincidence.  We model the outputs of the soundfield microphone array as 
'W', the sum of all the capsules (in the typical case) and X, Y, and Z, the 
differences between pairs of capsules.  These correspond to a coincident set of 
a monopole and three orthogonal dipoles at the center of the array.  We know 
that that model is not exactly accurate, especially in the high-frequency 
case.  
At frequencies where the distance across the array is a significant fraction of 
a wavelength there is a significant phase difference between the various 
capsule 
signals with the result that the frequency responses of the array change, and 
that they also are direction dependent.  One way of looking at that result is 
that the free-field and diffuse-field frequency responses begin to differ from 
each other at high frequencies.  This really happens fairly abruptly, with the 
diffuse-field omni response rolling off quite rapidly above 10 kHz for 
soundfield arrays with the typical 1.47 cm radius.

This is not a good thing.  What makes it tolerable is that the diffuse-field 
response of even a small (1/2") omni starts to roll off at just a few kHz.  By 
that measure a soundfield microphone is quite a good !

Likewise, we wish that the behavior of a soundfield microphone array were ideal 
at low frequencies, but it's not.  depending on the direction of arrival some 
of 
the capsules will be nearer to the source than others, so the level and the 
boost due to proximity effect is greater for the near capsules than for the far 
capsules.  I believe that this effect is more significant for 'W' than for the 
dipole outputs, basically because we expect the dipole outputs to have 
proximity 
effect but not the monopole output.

We should keep in mind that the near-field behavior of even conventional 
monopole (pressure) and dipole (figure eight) microphones is not ideal.  As I 
mentioned above, the DF response of omni microphones rolls off quite early.  
The 
DF response of figure-eight microphones tends to be a bit better, although 
still 
not ideal.  Also, the nearfield properties of conventional figure eight 
microphones isn't ideal.

If one were to need a soundfield microphone with ideal directional properties, 
it seems as though the only option is something like the Microflown.  But that 
has it's own set of problems.


- Original Message 
From: Robert Greene 
To: Surround Sound discussion group 
Sent: Sat, July 23, 2011 5:45:48 PM
Subject: Re: [Sursound] the recent 2-channel 3D sound formats and their 
viability for actual 360 degree sound


I feel a little diffident in commenting on this in the presence of so many 
experts on the Soundfield mike in theory as well as in practice,
but unless I am misunderstanding how it works, there are VERY serious problems 
of other kinds with using it at the kinds of distances (fractions of a meter 
less than 1/2 , much less often enough) where proximity
effect becomes really major.

Namely, as I understand it, the way the B format signals are built is 
predicated 
upon the distances among the four capsules being quite small
compared to the distance of the source, for the following reason:
Compensation is needed for the fact that the capsules are on the faces of a 
tetrahedron, not coincident and all at the center. This compensation
is based on the fact that at reasonable distances to the source, the 
differences 
of the distances to the mikes is obtained by orthogonal projection on the axis 
of arrival of the sound(to a very good apporximation).

To make sense of this jargon, suppose a source is on the line that is equistant 
from three of the capsules.  Then its distance to those three
will always be the same, and if the source is reasonably far away the distance 
to the fourth capsule will be a constnat. This comes from the Pythagorean 
theorem limit case in effect: at large distances , the
difference between A to S and B to S is equal to the length of the projection 
of 
the line from A to B onto the line from A to S (or B to S these being parallel 
in the limit case).

If one does NOT have such large distance to the source, the variation of 
distances to the capsules will be extreme and also complicated.
Just think of how the distances to the four face centers of the tetrahedron 
will 
vary in odd ways when the source is close by!

So it seems to me(and I am prepared to be all wrong!) that
th

Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Sampo Syreeni]

On 2011-07-24, Fons Adriaensen wrote:

In a normal SF mic the effect could become significant if the distance 
between the capsules is a non-trivial fraction of the source distance 
AND of the wavelength, so not really at low F.


Does that really matter, though? I mean, by definition XYZ contain 
particle velocity (or time integrated pressure gradient, whichever you 
prefer). With a near source, that already ought to show the proximity 
effect as long as the mic does anything remotely ambisonic. How it was 
built doesn't really seem to affect the results at this level.


So looked at from another angle, most of the phase differences that 
Robert pointed to, whether because of the directivity of the capsules or 
because of the capsule spacing plus the following corrective filter, 
actually ought to be there. Otherwise the mic wouldn't be measuring 
velocity as at should. So in fact the problem is squarely in that the 
higher order components can't be fully suppressed, but fold into the 
mix.

--
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Fons Adriaensen]

On Sat, Jul 23, 2011 at 05:45:48PM -0700, Robert Greene wrote:

> To make sense of this jargon, suppose a source is on the line that is  
> equistant from three of the capsules.  Then its distance to those three
> will always be the same, and if the source is reasonably far away the  
> distance to the fourth capsule will be a constnat. This comes from the  
> Pythagorean theorem limit case in effect: at large distances , the
> difference between A to S and B to S is equal to the length of the  
> projection of the line from A to B onto the line from A to S (or B to S  
> these being parallel in the limit case).
>
> If one does NOT have such large distance to the source, the variation of  
> distances to the capsules will be extreme and also complicated.
> Just think of how the distances to the four face centers of the  
> tetrahedron will vary in odd ways when the source is close by!
>
> So it seems to me(and I am prepared to be all wrong!) that
> the Soundfield mike could not be expected to work at all well
> except when the source is quite far away--a matter of meters, not
> inches.  At close distances, there will be wild phase differentials among 
> the four mike capsule outputs of a kind that depends on the distance
> of the source from the center of the mike--something which the mike
> does not "know" so that it cannot be compensated for.
>
> Am I all wet here?

Just a little :-) See also my previous post which hints at
this as well.

For a classic soundfield mic (using directional capsules),
the 'velocity' signals (X,Y,Z) are formed mostly by using
the directiviy of the capsules. Imagine they are really
coincident. In that case it's just a matter of combining
the four signals in such proportions that the sum of the
omni components in each of them is zero and the fig-8 ones
combine in the right direction.

This is still the dominant mechanism if the capsules are
not really coincident. There will be a contribution from
the finite distance as well, but this will be quite small
at low F. It would require a 'Blumlein shuffler' to be of
the same order of magnitude as the contribution from the
directivity of the capsules themselves. This is what SF
mics using omnis on a sphere do - it requires significant
gain on difference signals at LF, and without that gain
X,Y,Z would be of very low magnitude at LF.

In a normal SF mic the effect could become significant if
the distance between the capsules is a non-trivial fraction
of the source distance AND of the wavelength, so not really
at low F.

Ciao,

-- 
FA

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Fons Adriaensen]

On Sat, Jul 23, 2011 at 09:35:41PM +0100, dave.mal...@york.ac.uk wrote:

>  I have an interesting question (well, I think it's interesting). The 
> Soundfield microphone, like any directional microphone, has a boosted 
> bass response to close sounds. When listening to this through a speaker 
> rig, we hear this boost and tend to interpret it as meaning the sound is 
> close especially in a dry acoustic with a Greene-Lee head brace etc., 
> etc.,. However, surely (unless I am being more dense than usual tonight) 
> this is a learnt response based on the behaviour we have heard from 
> directional mics? After all, taken individually, at those sort of 
> frequencies our ears are essentially omnidirectional and not subject to 
> bass boost (to anything like the same degree).

The individual capsules are directional and hence will show the bass
boost for a close source. Each of them is the sum of an omni and a
figure-of-eight in some ratio, assume for a moment that this ratio
is independent of frequency. 

Now if you combine them to form W, the fist order components are made
to cancel out, this means there is no bass boost in W (a tiny amount
remains in practice since the mics are never at exactly the same
distance from a source).

Conversely, our ears may be omnidirectional at LF, but using two of
them to 'measure' the gradient (which is what we do implicitly -
there is no other directional info at LF) would mean that the bass
boost is introduced anyway: it is a property of the near field of a
source, not of the receiver(s). 

Ciao,

-- 
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Sampo Syreeni]

On 2011-07-23, Robert Greene wrote:

I feel a little diffident in commenting on this in the presence of so 
many experts on the Soundfield mike in theory as well as in practice, 
but unless I am misunderstanding how it works, there are VERY serious 
problems of other kinds with using it at the kinds of distances 
(fractions of a meter less than 1/2 , much less often enough) where 
proximity effect becomes really major.


That is true as well. I seem to remember the original impetus for the 
reactivity and sound intensity talks a few years back eventually proved 
to be not so much about sound fields, but about the poor response of the 
classical SoundField design towards surrounding soundfields which had 
higher order components. Rejection of directional aliasing from the 
higher order components of the local soundfield, that is. Which is 
precisely which progressively mounts up when you bring a small source up 
close, and/or have a closeby reflective geometry (such as Angelo did in 
his car work, then).


It proved that SoundFields have no problem with out-of-phase zeroth and 
first order components, but in fact responded remarkably accurately to 
them; the only excluded explanation was directional aliasing rejection. 
Which in retrospect should be rather self-evident, shouldn't it? :)


Namely, as I understand it, the way the B format signals are built is 
predicated upon the distances among the four capsules being quite 
small compared to the distance of the source, for the following 
reason:


That, but not only that. They're also physically extensive, with an 
innate directivity of their own.


Compensation is needed for the fact that the capsules are on the faces 
of a tetrahedron, not coincident and all at the center.


Yes, and this is based on them having the cardioid characteristic, plus 
being approximately coincident. That is only an approximation in total, 
especially at the higher frequencies. Thus, the overall mic won't 
totally reject higher harmonics. Again, we've gone over similar 
considerations with Filippo in the past, just considering spherical 
clouds of omnis. I think we even got into topology, with the difference 
between just spherical clouds, and clouds on top of an acoustically 
opaque sphere. ;)


So it seems to me(and I am prepared to be all wrong!) that the 
Soundfield mike could not be expected to work at all well except when 
the source is quite far away--a matter of meters, not inches.


Long story short, I suspect very much the same, and I think there's 
already good empirical showing for the problems that follow, even on 
this very list.

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Sampo Syreeni]

On 2011-07-23, dave.mal...@york.ac.uk wrote:

(For some reason Dave H's post didn't arrive at me as-is. Dave Malham 
appears once quoted and Dave Hunt as twice, in below. Sorry about the 
hassle.)


I have an interesting question (well, I think it's interesting). The 
Soundfield microphone, like any directional microphone, has a boosted 
bass response to close sounds. When listening to this through a 
speaker rig, we hear this boost and tend to interpret it as meaning 
the sound is close especially in a dry acoustic with a Greene-Lee head 
brace etc., etc.,. However, surely (unless I am being more dense than 
usual tonight) this is a learnt response based on the behaviour we 
have heard from directional mics?


To a degree it is. I think the worst thing here is that we continuously 
close-mic acoustic sources, to "give them that close, intimate feel". 
That's originally about the proximity effect and about HF attenuation 
with distance, but since it's now a part of a culturally shared idiom as 
well, we associate extra power with it as such, beyond the mere 
psychoacoustics. Electronic distortion with its synthetic overtones 
doesn't help here, either.


But still, at the very bottom, you'd have this very same reaction 
because of the pure, physical acoustical proximity effect. E.g. I'm 
pretty sure someone like Philippo Fazi could explain with neat 
visualisation how the boundary conditions represented by the human head 
turn this curved wavefront reactivity into a noticeable bass-boost at 
the tympanic membrane, given the shape of the human head, upper torso 
and pinnae. It really isn't just about the reproduction technology; it's 
about how soundfields work and how we naturally perceive them from 
within them.


After all, taken individually, at those sort of frequencies our ears 
are essentially omnidirectional and not subject to bass boost (to 
anything like the same degree).


The NFC-HOA theory doesn't take into account how we hear things. It's a 
physical theory and not a psychoacoustic one. It just recreates 
soundfields, and lets us hear them as we happen to do. If we don't hear 
those spatially differentiated low frequencies, so what? They were still 
recreated with perfect fidelity, and we heard them as such. If perhaps 
losing some of the impact in the process, given that we're no blue 
whales.


If you then look at the second NFC-HOA paper, they actually exploit this 
fact to arrive at a lower energy intake transmission pipe. They don't go 
into psychoacoustics just yet, but they do cut out the huge low 
frequency anti-phase signals which come from the naïve soundfield 
reconstruction math.


You're right that POA assumes plane waves. The encoded signals are 
reproduced at the distance of the loudspeakers.


No. Those two are in direct contradiction. If a point source comes from 
the surface of the rig, it's going to be a spherical wave originating 
from that distance. If it's a planewave instead, it's either just a 
planewave, or a (very tight) approximation of an infinitely far-away 
point source (that also being a plane wave when you measure it locally).


The shelf filters in a BLaH compliant decoder are (as I understand 
it) an attempt to compensate for the speakers finite distance, and 
that they don't produce plane waves at the listener. This is often 
referred to as 'distance compensation'.


Sorta. In the conventional ambisonic decoder there are two separate 
circuits. The first (set) is the shelf one, which is based on 
psychoacoustics alone. In a sense it tries to compensate for the very 
low, seventies bandwidth of just four channels for periphony. It does so 
by frequency selectively varying the relative amplitude of the zeroth 
and first components. At low frequencies it goes with a velocity, or 
systematic decode, because there we seem to (or seemed to) hear 
interaural phase differences pretty well, but not the amplitude ones. 
Going higher up, the shelf filtering is optimized to reproduce power 
differences between the two ears, which seem(ed) to work pretty well for 
both a) a well-centered single listener, and b) for purely mathematical, 
statistical reasons for non-centered listeners as well.


This first circuitry is never something you can switch off in a 
conventional ambisonic decoder, because it's about pure psychoacoustical 
optimization, with regard to the pure, physical bound signal that is 
being received.


The distance compensation circuit on the other hand can be swiched on or 
off, because it has to do with the receiver end rig geometry, which is 
then naturally variable by design. In reality it too ought to be a 
continuous knob, just as the aspect ratio knob in the four speaker 
decoders is. But then this would lead to a total bitch of a filter 
circuit in the analog domain, for little gain in the usual domestic 
situation which ambisonic was originally aimed at. Thus, the classical 
decoders simply give you the choice of no distance compensation, or a 
swi

Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Robert Greene]

I feel a little diffident in commenting on this in the presence of so many 
experts on the Soundfield mike in theory as well as in practice,
but unless I am misunderstanding how it works, there are VERY serious 
problems of other kinds with using it at the kinds of distances (fractions 
of a meter less than 1/2 , much less often enough) where proximity

effect becomes really major.

Namely, as I understand it, the way the B format signals are built is 
predicated upon the distances among the four capsules being quite small

compared to the distance of the source, for the following reason:
Compensation is needed for the fact that the capsules are on the faces of 
a tetrahedron, not coincident and all at the center. This compensation
is based on the fact that at reasonable distances to the source, the 
differences of the distances to the mikes is obtained by orthogonal 
projection on the axis of arrival of the sound(to a very good 
apporximation).


To make sense of this jargon, suppose a source is on the line that is 
equistant from three of the capsules.  Then its distance to those three
will always be the same, and if the source is reasonably far away the 
distance to the fourth capsule will be a constnat. This comes from the 
Pythagorean theorem limit case in effect: at large distances , the
difference between A to S and B to S is equal to the length of the 
projection of the line from A to B onto the line from A to S (or B to S 
these being parallel in the limit case).


If one does NOT have such large distance to the source, the variation of 
distances to the capsules will be extreme and also complicated.
Just think of how the distances to the four face centers of the 
tetrahedron will vary in odd ways when the source is close by!


So it seems to me(and I am prepared to be all wrong!) that
the Soundfield mike could not be expected to work at all well
except when the source is quite far away--a matter of meters, not
inches.  At close distances, there will be wild phase differentials among 
the four mike capsule outputs of a kind that depends on the distance

of the source from the center of the mike--something which the mike
does not "know" so that it cannot be compensated for.

Am I all wet here?

Robert

On Sat, 23 Jul 2011, dave.mal...@york.ac.uk wrote:


Hi Folks,
I have an interesting question (well, I think it's interesting). The 
Soundfield microphone, like any directional microphone, has a boosted bass 
response to close sounds. When listening to this through a speaker rig, we 
hear this boost and tend to interpret it as meaning the sound is close 
especially in a dry acoustic with a Greene-Lee head brace etc., etc.,. 
However, surely (unless I am being more dense than usual tonight) this is a 
learnt response based on the behaviour we have heard from directional mics? 
After all, taken individually, at those sort of frequencies our ears are 
essentially omnidirectional and not subject to bass boost (to anything like 
the same degree).


Any thoughts, anyone?

 Dave
On Jul 23 2011, Dave Hunt wrote:


Hi again,


Date: Thu, 21 Jul 2011 21:01:41 +0300 (EEST)
From: Sampo Syreeni 

On 2011-07-21, Dave Hunt wrote:


There is certainly no consideration of values outside the unit  sphere.
[...]


Correct, and we've been here before.


We certainly have.


As BLaH points out, even the first
order decoder handles distance as well as it possibly can. So does the
SoundField mic on the encoding side.


The encoding and decoding are well matched. In some ways hardly 
surprising.



But the classical synthetic
encoding equation is for infinitely far away sources only, that is,
plane waves. Running the result through a proper, BLaH compliant  decoder
then reconstructs a simulacrum of such a plane wave, with first order
directional blurring, spatial aliasing caused by the discrete rig, and
the purposely imposed psychoacoustic optimizations overlaid on top of
the original, extended soundfield. So in fact it's wrong to say  that the
source is produced at the distance of the rig: instead it's produced
infinitely far away, modulo the above three complications. (That is
bound to be one part of why even synthetically panned sources localise
so nicely even when listening from outside the rig.)


I have already admitted the error of my original statement. You're  right 
that POA assumes plane waves. The encoded signals are  reproduced at the 
distance of the loudspeakers. The shelf filters in  a BLaH compliant 
decoder are (as I understand it) an attempt to  compensate for the speakers 
finite distance, and that they don't  produce plane waves at the listener. 
This is often referred to as  'distance compensation'.



If you want to synthetically encode a near-field source so to speak  "by
the book", you'll have to lift the source term from Daniel, Nicol and
Moreau's NFC work. I seem to remember it amounts to a first order  filter
on the first order part of the source signal in the continuous domain,
which you'l

Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[dave . malham]

Hi Folks,
 I have an interesting question (well, I think it's interesting). The 
Soundfield microphone, like any directional microphone, has a boosted bass 
response to close sounds. When listening to this through a speaker rig, we 
hear this boost and tend to interpret it as meaning the sound is close 
especially in a dry acoustic with a Greene-Lee head brace etc., etc.,. 
However, surely (unless I am being more dense than usual tonight) this is a 
learnt response based on the behaviour we have heard from directional 
mics? After all, taken individually, at those sort of frequencies our ears 
are essentially omnidirectional and not subject to bass boost (to anything 
like the same degree).


Any thoughts, anyone?

  Dave
On Jul 23 2011, Dave Hunt wrote:


Hi again,


Date: Thu, 21 Jul 2011 21:01:41 +0300 (EEST)
From: Sampo Syreeni 

On 2011-07-21, Dave Hunt wrote:

There is certainly no consideration of values outside the unit  
sphere.

[...]


Correct, and we've been here before.


We certainly have.


As BLaH points out, even the first
order decoder handles distance as well as it possibly can. So does the
SoundField mic on the encoding side.


The encoding and decoding are well matched. In some ways hardly  
surprising.



But the classical synthetic
encoding equation is for infinitely far away sources only, that is,
plane waves. Running the result through a proper, BLaH compliant  
decoder

then reconstructs a simulacrum of such a plane wave, with first order
directional blurring, spatial aliasing caused by the discrete rig, and
the purposely imposed psychoacoustic optimizations overlaid on top of
the original, extended soundfield. So in fact it's wrong to say  
that the

source is produced at the distance of the rig: instead it's produced
infinitely far away, modulo the above three complications. (That is
bound to be one part of why even synthetically panned sources localise
so nicely even when listening from outside the rig.)


I have already admitted the error of my original statement. You're  
right that POA assumes plane waves. The encoded signals are  
reproduced at the distance of the loudspeakers. The shelf filters in  
a BLaH compliant decoder are (as I understand it) an attempt to  
compensate for the speakers finite distance, and that they don't  
produce plane waves at the listener. This is often referred to as  
'distance compensation'.


If you want to synthetically encode a near-field source so to speak  
"by

the book", you'll have to lift the source term from Daniel, Nicol and
Moreau's NFC work. I seem to remember it amounts to a first order  
filter

on the first order part of the source signal in the continuous domain,
which you'll then have to discretize. (But don't take my word for it,
it's been a while since I went through DN&R.)


Me too, but as I remember it tries to build the 'distance  
compensation' into the encoding, and thus is dependent on the  
distance of the loudspeakers. Thus the encoding is only suitable for  
an identical or similar rig, and is not transferable to other rigs.  
Amplitude/delay based systems such as WFS, Delta stereophony and  
TiMax have similar problems. The encoding has to be matched to the  
speaker rig.



 Simply
manipulating the relative amplitude or even the spectral contour  
doesn't

in theory cut it, though it's a cheap way to get some of the
psychoacoustic effects of a nearby source.


Agreed that it is far from perfect, but this is obviously not a  
trivial problem. What I'm suggesting is a fudge, though it can  
produce simulations of sources both inside and outside the  
loudspeaker radius which can be psychoacoustically effective, and are  
transferable to different rigs.


We're still left with the "40 foot high geese" problem.


 The only minor nit is that synthetic
panning needs a bit more refinement for near sources that wasn't being
handled by the older literature.


The "(potentially nasty) bass boost" you refer to is obviously a  
problem. You could limit it from going extremely large at very small  
distances, and ensure that  the output only went to 0dBFS maximum,  
but this would require a huge dynamic range throughout the whole  
system: large bit depth, good DACs, very quiet amplifiers etc..


If you could do the encoding assuming a given speaker distance, then  
modify the decoding for a different distance it might help, though  
I've no idea how to do this.


Ciao,

Dave Hunt

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Dave Hunt]

Hi again,


Date: Thu, 21 Jul 2011 21:01:41 +0300 (EEST)
From: Sampo Syreeni 

On 2011-07-21, Dave Hunt wrote:

There is certainly no consideration of values outside the unit  
sphere.

[...]


Correct, and we've been here before.


We certainly have.


As BLaH points out, even the first
order decoder handles distance as well as it possibly can. So does the
SoundField mic on the encoding side.


The encoding and decoding are well matched. In some ways hardly  
surprising.



But the classical synthetic
encoding equation is for infinitely far away sources only, that is,
plane waves. Running the result through a proper, BLaH compliant  
decoder

then reconstructs a simulacrum of such a plane wave, with first order
directional blurring, spatial aliasing caused by the discrete rig, and
the purposely imposed psychoacoustic optimizations overlaid on top of
the original, extended soundfield. So in fact it's wrong to say  
that the

source is produced at the distance of the rig: instead it's produced
infinitely far away, modulo the above three complications. (That is
bound to be one part of why even synthetically panned sources localise
so nicely even when listening from outside the rig.)


I have already admitted the error of my original statement. You're  
right that POA assumes plane waves. The encoded signals are  
reproduced at the distance of the loudspeakers. The shelf filters in  
a BLaH compliant decoder are (as I understand it) an attempt to  
compensate for the speakers finite distance, and that they don't  
produce plane waves at the listener. This is often referred to as  
'distance compensation'.


If you want to synthetically encode a near-field source so to speak  
"by

the book", you'll have to lift the source term from Daniel, Nicol and
Moreau's NFC work. I seem to remember it amounts to a first order  
filter

on the first order part of the source signal in the continuous domain,
which you'll then have to discretize. (But don't take my word for it,
it's been a while since I went through DN&R.)


Me too, but as I remember it tries to build the 'distance  
compensation' into the encoding, and thus is dependent on the  
distance of the loudspeakers. Thus the encoding is only suitable for  
an identical or similar rig, and is not transferable to other rigs.  
Amplitude/delay based systems such as WFS, Delta stereophony and  
TiMax have similar problems. The encoding has to be matched to the  
speaker rig.



 Simply
manipulating the relative amplitude or even the spectral contour  
doesn't

in theory cut it, though it's a cheap way to get some of the
psychoacoustic effects of a nearby source.


Agreed that it is far from perfect, but this is obviously not a  
trivial problem. What I'm suggesting is a fudge, though it can  
produce simulations of sources both inside and outside the  
loudspeaker radius which can be psychoacoustically effective, and are  
transferable to different rigs.


We're still left with the "40 foot high geese" problem.


 The only minor nit is that synthetic
panning needs a bit more refinement for near sources that wasn't being
handled by the older literature.


The "(potentially nasty) bass boost" you refer to is obviously a  
problem. You could limit it from going extremely large at very small  
distances, and ensure that  the output only went to 0dBFS maximum,  
but this would require a huge dynamic range throughout the whole  
system: large bit depth, good DACs, very quiet amplifiers etc..


If you could do the encoding assuming a given speaker distance, then  
modify the decoding for a different distance it might help, though  
I've no idea how to do this.


Ciao,

Dave Hunt

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Sampo Syreeni]

On 2011-07-21, Dave Hunt wrote:

There is certainly no consideration of values outside the unit sphere. 
[...]


Correct, and we've been here before. As BLaH points out, even the first 
order decoder handles distance as well as it possibly can. So does the 
SoundField mic on the encoding side. But the classical synthetic 
encoding equation is for infinitely far away sources only, that is, 
plane waves. Running the result through a proper, BLaH compliant decoder 
then reconstructs a simulacrum of such a plane wave, with first order 
directional blurring, spatial aliasing caused by the discrete rig, and 
the purposely imposed psychoacoustic optimizations overlaid on top of 
the original, extended soundfield. So in fact it's wrong to say that the 
source is produced at the distance of the rig: instead it's produced 
infinitely far away, modulo the above three complications. (That is 
bound to be one part of why even synthetically panned sources localise 
so nicely even when listening from outside the rig.)


If you want to synthetically encode a near-field source so to speak "by 
the book", you'll have to lift the source term from Daniel, Nicol and 
Moreau's NFC work. I seem to remember it amounts to a first order filter 
on the first order part of the source signal in the continuous domain, 
which you'll then have to discretize. (But don't take my word for it, 
it's been a while since I went through DN&R.) That not only affects the 
relative amplitude of the zeroth and first order components, but also 
leads to a (potentially nasty) bass boost (because of the proximity 
effect; this is why NFC-HOA went from an infinite encoding/transmission 
radius to a fixed, finite one), and a definite phase difference between 
the orders (because near fields of even freely radiating sources are 
reactive due to spatial curvature of the pressure wavefront). Simply 
manipulating the relative amplitude or even the spectral contour doesn't 
in theory cut it, though it's a cheap way to get some of the 
psychoacoustic effects of a nearby source.


As for the rig term in the NFC work, that's already there in POA's 
distance compensation circuitry, and introduces similar (but opposing) 
effects, based on the finite distance of the rig. (BTW, in Gerzon's 
opinion it was the phase shift which mattered the most here, so by 
extension it's likely highly significant for the encoding part as well.) 
That is, a correctly setup (i.e. BLaH compliant) classical Ambisonics 
system is precisely equivalent to a first order NFC-HOA one, and absent 
the three complications I mentioned, is 100% a holophonic reproduction 
system, just isotropically spatially blurred to the to the degree 
dictated by the first order basis functions (when thought of as 
spherical convolution kernels). The only minor nit is that synthetic 
panning needs a bit more refinement for near sources that wasn't being 
handled by the older literature.

--
Sampo Syreeni, aka decoy - de...@iki.fi, http://decoy.iki.fi/front
+358-50-5756111, 025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Dave Hunt]

Hi again,


Date: Thu, 21 Jul 2011 12:45:45 -
From: Richard Lee 

It is true that 1st order ambisonics doesn't consider distance,  
with all

sources being reproduced at the distance of the speakers,
.

synthesis, the ambisonic encoding equations do not include distance,


Both of these are untrue.

For the second, see the Appendix of BLaH3 "Is my decoder  
Ambisonic?" Heller

et al, AES San Francisco, 2008


Looking again at the equations, it is not so clear. As normally  
expressed in cartesian coordinates (x,y,z, all limited to values  
between -1 and +1) they do within the unit sphere (the distance of  
the speakers), but in polar coordinates there is unity magnitude of  
the vector, and everything is on the unit sphere.


These equations are only really useful when we wish to pan a mono  
source ambisonically, what might be called spatial synthesis or  
coding. Within the unit sphere they lead to 2nd and above components  
going to zero at zero distance, and Gerzon/Malham?? suggested  
increasing W inside the sphere to maintain the same apparent loudness.


There is certainly no consideration of values outside the unit  
sphere. To take just the 1st order, the X signal in cartesian  
coordinates = S*x, S being the amplitude of the source and x its  
front/back distance. This would lead to increasing amplitude of the X  
signal with distance, obviously the opposite of what is observed.


So any attempt to simulate distance has to rely on other descriptions  
of what happens physically. In anechoic conditions a good start is  
the inverse square law: amplitude varies with 1/d. We can get round  
the problem of this going to infinity at zero distance by simply  
adding 1, so the listener is at distance 1, and the speakers at  
distance 2. This somehow fits with a curious ambisonic paradox: the  
microphone and the listener are at distance zero, and the speakers at  
distance 1.


This leads to the energy being 6dB lower at the speaker distance, and  
unity gain at zero. Without some sort of reverb model this sounds  
much too extreme, and many prefer a 1/sqrt(d) law, rather curiously  
the law that Chowning suggests for the amplitude of indirect  
reflected sound.



There are two convenient proofs of the fallacy of the first.


I admit to not being careful enough in my phrasing of my assertion.  
The B-Format (or higher order) signals, rather than the original  
sound sources, are reproduced at the distance of the speakers. I  
thought that I had also written (though obviously omitted to) that  
recordings, and microphone signals in general, contain distance  
information: they reproduce what would be heard acoustically to a  
greater or lesser degree.


So, I agree with what you say, though I was talking about ambisonic  
synthesis and should have made that clearer.



While making a normal recording, creep silently up to your TetraMic or
Soundfield and whisper into it.

When you play this back to an unsuspecting victim seated in the  
centre of a
simple Classic Ambisonic rig, he will flinch.  He certainly doesn't  
hear

you at the radius of the speakers.

The other 'proof' is the B-format motorcycle that Soundfield have  
played at
nauseum at various shows.  Ambisonic myth has it that this was  
recorded by

the young Dr. Peter Lennox on Grand Vizier Malham's modified Calrec
Soundfield Mk 3A while the Vizier was away on a diplomatic visit to  
the
Great Turtle that Supports the Universe.  This mike was one of the  
first to
have IMHO, the proper EQ which allow a Soundfield to implement the  
correct

Ambisonic Encoding Eqns in the Appendix of BLaH3.



Ciao,

Dave Hunt
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[dave . malham]

On Jul 21 2011, "Bearcat M. Şandor" wrote:


On 07/20/2011 03:49 AM, Richard Dobson wrote:
So - noisy pterodactyls and dragons are mixing it with the brass 
section. How weird is that likely to sound? Especially if the music 
track itself has been recorded in surround the way so many people 
enthuse about here"?



Dragons in the Brass section?  I think groups like Blind Guardian would
embrace this format in that case. :")



Weird, I did a search for Blind Guardian but accidentally typed "Gau" and 
came up with;


BLIND BEAMFORMING FOR NON GAUSSIAN SIGNALS by Jean-Françcois Cardoso ...
perso.telecom-paristech.fr/~cardoso/Papers.PDF/iee.pdf

which seems strangely connected with making higher order microphones


  Dave M.
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[dave . malham]

On Jul 20 2011, Dave Hunt wrote:


Hi,


Date: 20 Jul 2011 11:36:10 +0100
From: dave.mal...@york.ac.uk

Hi all,
   I think that one of the problems with all these discussions is  
that we
tend to think of the distance of an audio object as being the  
exactly the
same sort of thing as the coordinates of the object w.r.t. the  
listener -

but it's not because, unlike direction, we humans can't determine it
absolutely, but only as implied via the object's (and our)  
interaction with
the environment. For a unknown distant stationary source in an  
anechoic
environment there are _no_ cues as to distance, unless the listener  
can

move and gain something via parallax or loudness variation. For close
sources (i.e. in the curved wavefront zone) there may be some cues  
from
bass lift, but even these would be ambiguous for median plane  
sources if

head turning is not allowed (Greene-Lee head brace, anyone?)

   Dave M.


Agreed, though you are really talking of a particular (and fairly  
uncommon) situation. An unknown sound source, which implies something  
electronically generated, and thus with no readily identifiable  
source. An anechoic environment.


Absolutely, I was taking it ad absurdum to illustrate the point that 
(assuming no movement, including head turning) the only thing we get that 
isn't about experience or environmental interaction is direction. Even 
then, without head movement and/or prior knowledge (needed to allow higher 
order components of HRTF's to come into play), anomalies are possible - cf 
cones of confusion.




Apart from HF absorption by the air, only really appreciable at quite  
large distances, the only variable is then loudness, the same sound  
louder or quieter. As we have no knowledge as to how loud it is  
supposed to be at a given distance, we have no reference point for  
comparison.




Absolutely (again) and even on familiar(is) sounds, experiments in anechoic 
rooms have shown that large errors occur for simple loudness based distance 
estimation.




  Dave M.


In a 'soundscape' containing several sources some distance  
relationships between them can be discerned. Of course this is aided  
by prior experience. Given a recognisable sound source, such as a  
blackbird or violin, amplitude alone gives some rough idea of  
distance, though it cannot be stated with any accuracy. Given two  
familiar sources, a rough relative distance between them can be  
perceived.


Any sense of scale can be disrupted by playback levels that are  
louder or quieter than 'real' levels. Loud sounds are more  
'present' (nearer ?), and are usually produced by larger sources.


I, like I suspect many on this list, am interested in how aural  
compositions can be made spatially 'effective': to convey convincing  
and believable images, even if they are 'unrealistic'. Most modern  
audio production for music, film or any other medium aims to produce  
something 'hyper-real': clear, polished, stripped of extraneous  
sound, crafted. The listener is usually static.


Ciao,

Dave Hunt
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Bearcat M. Şandor]

On 07/20/2011 03:49 AM, Richard Dobson wrote:
>So - noisy pterodactyls and dragons are mixing it with the brass section. How 
>weird
> is that likely to sound? Especially if the music track itself has been
> recorded in surround the way so many people enthuse about here"?
> 
Dragons in the Brass section?  I think groups like Blind Guardian would
embrace this format in that case. :")



-- 
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Cell: 406.210.3500
Jabber/xmpp/gtalk/email: bear...@feline-soul.net
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Richard Lee]

> It is true that 1st order ambisonics doesn't consider distance, with all 
sources being reproduced at the distance of the speakers,
.
> synthesis, the ambisonic encoding equations do not include distance,

Both of these are untrue.

For the second, see the Appendix of BLaH3 "Is my decoder Ambisonic?" Heller 
et al, AES San Francisco, 2008

There are two convenient proofs of the fallacy of the first.

While making a normal recording, creep silently up to your TetraMic or 
Soundfield and whisper into it.

When you play this back to an unsuspecting victim seated in the centre of a 
simple Classic Ambisonic rig, he will flinch.  He certainly doesn't hear 
you at the radius of the speakers.

The other 'proof' is the B-format motorcycle that Soundfield have played at 
nauseum at various shows.  Ambisonic myth has it that this was recorded by 
the young Dr. Peter Lennox on Grand Vizier Malham's modified Calrec 
Soundfield Mk 3A while the Vizier was away on a diplomatic visit to the   
Great Turtle that Supports the Universe.  This mike was one of the first to 
have IMHO, the proper EQ which allow a Soundfield to implement the correct 
Ambisonic Encoding Eqns in the Appendix of BLaH3.

BTW, real human distance perception is TERRIBLE under anechoic conditions 
cos waveform curvature is about the only thing left.  Those of you 
investigating distance perception, please take note.

And you need a proper Classic Ambi decoder as defined by MAG and BLaH3 with 
NFC.
_

Why does this work?

At LF, simple 1st order Ambisonics with NFC IS a wavefield / soundfield 
reconstruction system.

Then there's the snake oil in Calrec Soundfields, hand squeezed from solid 
Unobtainium by Yorkshire virgins ...  Shaddup Lee!  Just Shaddup!

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Robert Greene]

PS FIrst line refers to Dave's message not mine

Also some words got left out--
later on in the opening of the second paragraph it
is supposed to say that one cannot expect to hear
any kind of exact distance except
if things are very near by

On Wed, 20 Jul 2011, Robert Greene wrote:



Here is the truth!
I have spent a LOT of time at live musical events(when
the music was not too interesting , while I waited
for what I came to hear or just sat through if I had
gone for some social reason only) listening with my eyes closed
to whether one could hear the distance of things.

My admittedly informal conclusion is that one cannot except
if things are very near by(e.g. near by instruments in the
orchestra when I am playing). In the audience at a fair distance
from the orchestra, one has some impression that the orchestra
is not really close. It sounds tonally different from what it
would sound like up close and the shape of the dynamics is different
(more reverb field, less direct arrival).
But where is the orchestra? It is just kind of "out there".
THere is no real feeling of exactly how far it is out there
at all, none to speak of.

It seems to me pretty clear that such a rather vague and generalized
feeling prevents--for this type of music--the whole idea of
distance from being really important musically.

Theoretically, yes, musically no--one just does not hear it.

The trouble with stereo is that it is too close and too little.
Surrounds to make for realism (of orchestral music) needs to make
the orchestra seem either larger or further away---because 2 speaker
stereo does tend to localize things at a fairly definite distance,
more or less at the plane of the speakers--unless you do it awfully well and 
then it doesn't do that so much.


Stereo orchestral music sounds weird because it is tonally close
(usually) but physically way too small for the tonal closeness and
the plane of the speakers closeness just makes things even worse.
WHen you are 15 feet from it, an orchestra--being about 60 feet wide 
usually--subtends a huge angle and is LARGE. And actually at that close

range it has front to back depth too--that is still close enough for that.

Robert


On Wed, 20 Jul 2011, dave.mal...@york.ac.uk wrote:


Hi all,
 I think that one of the problems with all these discussions is that we 
tend to think of the distance of an audio object as being the exactly the 
same sort of thing as the coordinates of the object w.r.t. the listener - 
but it's not because, unlike direction, we humans can't determine it 
absolutely, but only as implied via the object's (and our) interaction with 
the environment. For a unknown distant stationary source in an anechoic 
environment there are _no_ cues as to distance, unless the listener can 
move and gain something via parallax or loudness variation. For close 
sources (i.e. in the curved wavefront zone) there may be some cues from 
bass lift, but even these would be ambiguous for median plane sources if 
head turning is not allowed (Greene-Lee head brace, anyone?)


 Dave M.

On Jul 20 2011, Dave Hunt wrote:


Hi,



Modelling distance, and controlling it on a per source basis, is  founded 
on sound physical principles and can be made 'convincing',  even with low 
order ambisonics. Agreed that it is 'bolted on', though  synthesis (being 
the converse of analysis) involves controlling a  large number of 
parameters to simulate what occurs naturally.


Even WFS, as described in the literature, suggests that sources be 
recorded individually as dry and close as possible, and the 'scene'  then 
reconstructed on playback. So it too synthesises distance.


Ciao,

Dave Hunt

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Robert Greene]

Here is the truth!
I have spent a LOT of time at live musical events(when
the music was not too interesting , while I waited
for what I came to hear or just sat through if I had
gone for some social reason only) listening with my eyes closed
to whether one could hear the distance of things.

My admittedly informal conclusion is that one cannot except
 if things are very near by(e.g. near by instruments in the
orchestra when I am playing). In the audience at a fair distance
from the orchestra, one has some impression that the orchestra
is not really close. It sounds tonally different from what it
would sound like up close and the shape of the dynamics is different
(more reverb field, less direct arrival).
But where is the orchestra? It is just kind of "out there".
THere is no real feeling of exactly how far it is out there
at all, none to speak of.

It seems to me pretty clear that such a rather vague and generalized
feeling prevents--for this type of music--the whole idea of
distance from being really important musically.

Theoretically, yes, musically no--one just does not hear it.

The trouble with stereo is that it is too close and too little.
Surrounds to make for realism (of orchestral music) needs to make
the orchestra seem either larger or further away---because 2 speaker
stereo does tend to localize things at a fairly definite distance,
more or less at the plane of the speakers--unless you do it awfully well 
and then it doesn't do that so much.


Stereo orchestral music sounds weird because it is tonally close
(usually) but physically way too small for the tonal closeness and
the plane of the speakers closeness just makes things even worse.
WHen you are 15 feet from it, an orchestra--being about 60 feet wide 
usually--subtends a huge angle and is LARGE. And actually at that close

range it has front to back depth too--that is still close enough for that.

Robert


On Wed, 20 Jul 2011, dave.mal...@york.ac.uk wrote:


Hi all,
 I think that one of the problems with all these discussions is that we tend 
to think of the distance of an audio object as being the exactly the same 
sort of thing as the coordinates of the object w.r.t. the listener - but it's 
not because, unlike direction, we humans can't determine it absolutely, but 
only as implied via the object's (and our) interaction with the environment. 
For a unknown distant stationary source in an anechoic environment there are 
_no_ cues as to distance, unless the listener can move and gain something via 
parallax or loudness variation. For close sources (i.e. in the curved 
wavefront zone) there may be some cues from bass lift, but even these would 
be ambiguous for median plane sources if head turning is not allowed 
(Greene-Lee head brace, anyone?)


 Dave M.

On Jul 20 2011, Dave Hunt wrote:


Hi,



Modelling distance, and controlling it on a per source basis, is  founded 
on sound physical principles and can be made 'convincing',  even with low 
order ambisonics. Agreed that it is 'bolted on', though  synthesis (being 
the converse of analysis) involves controlling a  large number of 
parameters to simulate what occurs naturally.


Even WFS, as described in the literature, suggests that sources be 
recorded individually as dry and close as possible, and the 'scene'  then 
reconstructed on playback. So it too synthesises distance.


Ciao,

Dave Hunt

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Dave Hunt]

Hi,


Date: 20 Jul 2011 11:36:10 +0100
From: dave.mal...@york.ac.uk

Hi all,
   I think that one of the problems with all these discussions is  
that we
tend to think of the distance of an audio object as being the  
exactly the
same sort of thing as the coordinates of the object w.r.t. the  
listener -

but it's not because, unlike direction, we humans can't determine it
absolutely, but only as implied via the object's (and our)  
interaction with
the environment. For a unknown distant stationary source in an  
anechoic
environment there are _no_ cues as to distance, unless the listener  
can

move and gain something via parallax or loudness variation. For close
sources (i.e. in the curved wavefront zone) there may be some cues  
from
bass lift, but even these would be ambiguous for median plane  
sources if

head turning is not allowed (Greene-Lee head brace, anyone?)

   Dave M.


Agreed, though you are really talking of a particular (and fairly  
uncommon) situation. An unknown sound source, which implies something  
electronically generated, and thus with no readily identifiable  
source. An anechoic environment.


Apart from HF absorption by the air, only really appreciable at quite  
large distances, the only variable is then loudness, the same sound  
louder or quieter. As we have no knowledge as to how loud it is  
supposed to be at a given distance, we have no reference point for  
comparison.


In a 'soundscape' containing several sources some distance  
relationships between them can be discerned. Of course this is aided  
by prior experience. Given a recognisable sound source, such as a  
blackbird or violin, amplitude alone gives some rough idea of  
distance, though it cannot be stated with any accuracy. Given two  
familiar sources, a rough relative distance between them can be  
perceived.


Any sense of scale can be disrupted by playback levels that are  
louder or quieter than 'real' levels. Loud sounds are more  
'present' (nearer ?), and are usually produced by larger sources.


I, like I suspect many on this list, am interested in how aural  
compositions can be made spatially 'effective': to convey convincing  
and believable images, even if they are 'unrealistic'. Most modern  
audio production for music, film or any other medium aims to produce  
something 'hyper-real': clear, polished, stripped of extraneous  
sound, crafted. The listener is usually static.


Ciao,

Dave Hunt
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Dave Hunt wrote:



It is true that 1st order ambisonics doesn't consider distance, with  
all sources being reproduced at the distance of the speakers,  
although Gerzon did consider distance panning. A Soundfield mic  
recording contains distance information. If attempting spatial  
synthesis, the ambisonic encoding equations do not include distance,  
and this has to be added in various ways: amplitude variation  
(inverse square or other law), hf air absorption, early reflections  
and reverberation in a virtual space, source directivity, occluding  
objects etc..


Sources inside the speaker distance cannot be be correctly  
represented with 1st order ambisonics, as the x,y,z components all  
diminish to zero at the listeners position, and this can be  
compensated to some extent by increasing W to maintain a similar  
loudness. As far as I can see, higher order components also tend  
towards zero (apart from R, which tends towards a constant of -0.5).  
Modelling near sources in HOA seems to depend mostly on the  
'proximity effect': an increase of gain at low frequencies in the  
directional components.


I'm not sure that this is really 'gimmickry' as Jörn suggests.



Hi...

I would highly suspect that some 3D audio game engines (Codemasters, for 
example "DiRT" series) are considering distance cues. Although I don't 
know this, I believe this would add a lot to a more realistic game 
impression.


The fact that many people don't consider distance as some important 
parameter doesn't mean it is a "gimmick", agreed.



Thanks for the clarifications!

Stefan

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Thanks for your (thoughtful) answer.

IMO it is not very efficient to (en)code 3D audio in maybe 32 audio 
tracks (including some metadata, tracks maybe in 96Hz), or to 
transmit/store even more "audio objects".


Therefore, they should consider or include Ambisonics (up to 3rd or 4th 
order) into the standard.


Question: Could the F-M HOA system be extended to include (just) 4th 
order? (We might talk about cinema applications here. Although 3rd order 
would probably be "good enough", to include 4th order would be even better.)


Thanks,

Stefan



Dave Malham wrote:




On 20/07/2011 01:07, Stefan Schreiber wrote:


Dave Malham wrote:



Surround is not just about Ambisonics and maybe WFS, yet again.




True - but they are ones that work and are well established.

Dave




Ambisonics and WFS are well-established?! Depends on your view on 
this...



In the sense that the technology is well developed and that there are 
an increasing number of applications of both, though, I would agree, 
not in a mass market (yet)


It also sounds  as if Ambisonics and WFS don't have some drawbacks, 
and of course both systems have some.




Indeed they have drawbacks - engineering is like that, always about 
making compromises, good engineering is about attempting to make 
optimal compromises. :-)


You "review" a system (SRS, CC3D) you even don't know enough,  and 
obviously in a negative ("snake oil")  way. IMO they are trying to 
develop a system which covers some demand from outside. "Cinema" is 
in the name of CC3D. Even if they are copying some elements from 
elsewhere, I think this is still ok. There seem to be some new 
aspects. On a system level, you can't say SRS is copying anything 
else, because there is no established parametric/object-based 3D 
audio system elsewhere which they could copy.



Sorry, but their blurb reads like snake oil sales talk so I called it 
that. It wasn't a comment on the system - since I haven't heard it and 
have no technical information to go on, I couldn't do so. It would, of 
course, not be unknown for companies who want to keep IP secret to 
deliberately obfuscate things


Hmm, reading through this, it seems that basically they've 
discovered MPEG4 Spatial Audio Object Coding :-) 



Was this about 3D audio? Doubt this... And anyway, outside from 
academic research nobody has implemented this.




I'm not sure about that.

For my part, I will try to get more information about this. However, 
I could imagine why SRS won't discuss their system on this list.




Look forward to hearing all about it...

  Dave



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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[dave . malham]

Hi all,
  I think that one of the problems with all these discussions is that we 
tend to think of the distance of an audio object as being the exactly the 
same sort of thing as the coordinates of the object w.r.t. the listener - 
but it's not because, unlike direction, we humans can't determine it 
absolutely, but only as implied via the object's (and our) interaction with 
the environment. For a unknown distant stationary source in an anechoic 
environment there are _no_ cues as to distance, unless the listener can 
move and gain something via parallax or loudness variation. For close 
sources (i.e. in the curved wavefront zone) there may be some cues from 
bass lift, but even these would be ambiguous for median plane sources if 
head turning is not allowed (Greene-Lee head brace, anyone?)


  Dave M.

On Jul 20 2011, Dave Hunt wrote:


Hi,



Modelling distance, and controlling it on a per source basis, is  
founded on sound physical principles and can be made 'convincing',  
even with low order ambisonics. Agreed that it is 'bolted on', though  
synthesis (being the converse of analysis) involves controlling a  
large number of parameters to simulate what occurs naturally.


Even WFS, as described in the literature, suggests that sources be  
recorded individually as dry and close as possible, and the 'scene'  
then reconstructed on playback. So it too synthesises distance.


Ciao,

Dave Hunt

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Richard Dobson]

On 20/07/2011 09:53, Dave Malham wrote:
...


Sorry, but their blurb reads like snake oil sales talk so I called it
that. It wasn't a comment on the system - since I haven't heard it and
have no technical information to go on, I couldn't do so. It would, of
course, not be unknown for companies who want to keep IP secret to
deliberately obfuscate things


Hmm, reading through this, it seems that basically they've discovered
MPEG4 Spatial Audio Object Coding :-)





An interesting part of that feature was the discussion, such as it was, 
of the location of the music in a strongly spatialsed scene. Of course, 
with a vanilla cinema surround scene, where nothing actually sounds 
particularly realistic spatially (beyond crude panning), having some 
disembodied music track is a familiar thing relying on the same 
automatic suspension of disbelief which allows us to imagine there is no 
camera crew in the scene either, and accepts the sound of explosions in 
space. But in a genuinely spatialised scene, presumably with the goal of 
hyper-realism, the music, apparently, remains "... perfectly isolated 
and anchored above and well forward of the screen". So - noisy 
pterodactyls and dragons are mixing it with the brass section. How weird 
is that likely to sound? Especially if the music track itself has been 
recorded in surround the way so many people enthuse about here"?


Richard Dobson
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Dave Hunt]

Hi,


The next thing that you heard with CC3D was another psychoacoustic
phenomenon that we kind of discovered last year about what sounds do
when they come closer versus moving farther away. And we found  
that we

were able to simulate something that normally can?t be done with
traditional surround sound, which is proximity.




And again, that?s not just amplitude. So we?re taking advantage of
what we learned there to create this feeling that things are being
projected into space in the D axis, the depth axis.



From: J?rn Nettingsmeier
so this is 4d spacetime, right? x, y, z, and d :)  now this funny  
drone

noise, is that minkowski spinning in his grave?


As Dave Malham has already pointed out, d can be expressed in terms  
of x,y,z, so is not an independent coordinate. This is like trying to  
combine two coordinate systems describing the same position  
(Cartesian and Polar), then saying we have six coordinates = 6D.



Date: Mon, 18 Jul 2011 09:17:41 +0100
From: Dave Malham 


classical ambisonics doesn't really do that. on good recordings,  
you will get a very nice sense of
distance, but that is due to distance cues which are more or less  
independent of ambisonics (any

good recording method can do it).
what you definitely won't get (with any order less than  
"ridiculously high") are sources closer

than the ring of speakers.

Whilst I agree that you can't generally get stationary audio  
objects closer than the radius of the
speakers on low order systems (currently, only high order Ambisonic  
systems, WFS or crosstalk
cancelled binaural systems can do that - oh, and the various  
ultrasound based speakers), you can get
reasonably quickly moving objects to appear to pass close by,  
especially if the acoustic of the
playback space is dead relative to the reproduced space, provided  
you give enough cues (particularly
early reflection patterns and proximity effect) in the soundscape  
to override the conflicting
playback space cues. Whilst this also occurs with any decent replay  
methodology,  it is easier with
Ambisonics because (I suspect) of the fact that there is always  
more than one speaker producing
sound, so the local space cues conflict not just with the  
soundscape cues, but also each other,

weakening the perceptual effects of the local cues.


It is true that 1st order ambisonics doesn't consider distance, with  
all sources being reproduced at the distance of the speakers,  
although Gerzon did consider distance panning. A Soundfield mic  
recording contains distance information. If attempting spatial  
synthesis, the ambisonic encoding equations do not include distance,  
and this has to be added in various ways: amplitude variation  
(inverse square or other law), hf air absorption, early reflections  
and reverberation in a virtual space, source directivity, occluding  
objects etc..


Sources inside the speaker distance cannot be be correctly  
represented with 1st order ambisonics, as the x,y,z components all  
diminish to zero at the listeners position, and this can be  
compensated to some extent by increasing W to maintain a similar  
loudness. As far as I can see, higher order components also tend  
towards zero (apart from R, which tends towards a constant of -0.5).  
Modelling near sources in HOA seems to depend mostly on the  
'proximity effect': an increase of gain at low frequencies in the  
directional components.


I'm not sure that this is really 'gimmickry' as J?rn suggests.


Date: Mon, 18 Jul 2011 19:27:26 +0200
From: J?rn Nettingsmeier 

distance cues are mostly gimmickry in my opinion. you can fake  
distance

in a number of ways, but most are really dependent on the spectrum and
envelope of the program material. most aspects of distance encoding  
are

also orthogonal to most surround techniques, which means they can be
added at will, today. they don't even necessitate a fancy new name.


Modelling distance, and controlling it on a per source basis, is  
founded on sound physical principles and can be made 'convincing',  
even with low order ambisonics. Agreed that it is 'bolted on', though  
synthesis (being the converse of analysis) involves controlling a  
large number of parameters to simulate what occurs naturally.


Even WFS, as described in the literature, suggests that sources be  
recorded individually as dry and close as possible, and the 'scene'  
then reconstructed on playback. So it too synthesises distance.


Ciao,

Dave Hunt

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Dave Malham]

On 20/07/2011 01:07, Stefan Schreiber wrote:

Dave Malham wrote:



Surround is not just about Ambisonics and maybe WFS, yet again.



True - but they are ones that work and are well established.

Dave



Ambisonics and WFS are well-established?! Depends on your view on this...


In the sense that the technology is well developed and that there are an increasing number of 
applications of both, though, I would agree, not in a mass market (yet)


It also sounds  as if Ambisonics and WFS don't have some drawbacks, and of course both systems 
have some.




Indeed they have drawbacks - engineering is like that, always about making compromises, good 
engineering is about attempting to make optimal compromises. :-)


You "review" a system (SRS, CC3D) you even don't know enough,  and obviously in a negative ("snake 
oil")  way. IMO they are trying to develop a system which covers some demand from outside. 
"Cinema" is in the name of CC3D. Even if they are copying some elements from elsewhere, I think 
this is still ok. There seem to be some new aspects. On a system level, you can't say SRS is 
copying anything else, because there is no established parametric/object-based 3D audio system 
elsewhere which they could copy.


Sorry, but their blurb reads like snake oil sales talk so I called it that. It wasn't a comment on 
the system - since I haven't heard it and have no technical information to go on, I couldn't do so. 
It would, of course, not be unknown for companies who want to keep IP secret to deliberately 
obfuscate things


Hmm, reading through this, it seems that basically they've discovered MPEG4 Spatial Audio Object 
Coding :-) 


Was this about 3D audio? Doubt this... And anyway, outside from academic research nobody has 
implemented this.




I'm not sure about that.

For my part, I will try to get more information about this. However, I could imagine why SRS won't 
discuss their system on this list.




Look forward to hearing all about it...

  Dave

--
 These are my own views and may or may not be shared by my employer
/*/
/* Dave Malham   http://music.york.ac.uk/staff/research/dave-malham/ */
/* Music Research Centre */
/* Department of Music"http://music.york.ac.uk/";   */
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Dave Malham wrote:


Hi Jörn,
   Saved me some typing - pretty well what I would have said :-)

   Dave


Absolutely same opinion, right? :-D



Surround is not just about Ambisonics and maybe WFS, yet again.



True - but they are ones that work and are well established.

Dave



Ambisonics and WFS are well-established?! Depends on your view on 
this... 

It also sounds  as if Ambisonics and WFS don't have some drawbacks, and 
of course both systems have some.


You "review" a system (SRS, CC3D) you even don't know enough,  and 
obviously in a negative ("snake oil")  way. IMO they are trying to 
develop a system which covers some demand from outside. "Cinema" is in 
the name of CC3D. Even if they are copying some elements from elsewhere, 
I think this is still ok. There seem to be some new aspects. On a system 
level, you can't say SRS is copying anything else, because there is no 
established parametric/object-based 3D audio system elsewhere which they 
could copy.


Hmm, reading through this, it seems that basically they've discovered 
MPEG4 Spatial Audio Object Coding :-) 


Was this about 3D audio? Doubt this... And anyway, outside from academic 
research nobody has implemented this.


For my part, I will try to get more information about this. However, I 
could imagine why SRS won't discuss their system on this list.


A slightly warmer reception for the "surround outsiders" might actually 
help...



Best,

Stefan




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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Ralph Glasgal]

There is now an Android app that includes RACE.  It was developed in Latvia and 
you can see it at www.neutronmp.com  It is basically a digital audio 
workstation with every option imaginable including an RTA, 32 bit processing, 
crossfading, dithering, more than 30 file formats, earphone crosstalk, 4 band 
graphic equalizer, and a long list more. Ambiophonics is the 5th option on the 
list.  How you can control all this with a small Droid tablet display is the 
mystery.
 So we now have Ambiophonic apps for the Apples and the Droids and they were 
independently produced.  With other XTC versions from Wareing and Choueiri not 
to mention TacT, Hong Kong, Hotto, and the VST guys, loudspeaker binaural is 
moving ahead.  Despite some earlier list comments head tracking is not needed 
by any of us.  The speakers do have to be closer.
 
Also, again, four speakers (a crosstalk cancelled pair in front and one behind) 
easily produces a 360 degree circle of sound in the horizontal plain starting 
with 4.0 media.  Yes, no height. Depending on the parmeters used, the 
recording, the speakers, etc. there is plenty of depth perception compared to 
stereo or 5.1  Choueiri is the best for this if you need proximity effects.  
But RACE does produce sounds that appear in front of (or behind) the plane of 
the speakers.
 
The use of Soundmatters foxL private wireless speakers makes producing a full 
width stage a cinch and also allows many viewers of a movie to enjoy the same 
stage.  (common subwoofer of course)  The rare earth technology in these one 
inch dual voice coil tweeter/woofers delivers a nearfield (laser-like) SPL of 
90 dB and a just usable response down to 80Hz thanks to the vibrating battery 
pack back panel.  Of course you can also use four quality speakers when you 
want to listen alone or with the family.  But the signals, even for high-end 
systems, will soon originate from tablet device directories and interfaces.
 
Something on a philosophical note:
 
All this Android/Apple stuff is for people under the age of 20.  Conventional 
electronic components will soon only be used by those still using Kodachrome 
film.  Everything will be tracks/files, mostly attached to Video or 
Games, controlled by Android or Apple tablets or smart phones.  Docking 
stations, soundbars, tiny subs, and car Droid consoles/adapters will be 
commonplace.  Also home theater projectors and the other large screen displays 
will be essentially Android or Apple controlled oversized tablets.  
TV/movie/music programs will be selected from the cloud.  The next generation 
will not know how to turn a knob or operate a CD player.  Many of these new 
devices will be cell phone capable as well.  The new cars like the Chevrolet 
Volt are already tablet computers on wheels.
 
I hope, that in this brave new world, RACE or similar will be one of the 
standard features and this seems to be happening a little bit.  The problem for 
Jambox and  Soundmatters is that their speakers are so small that they sound 
mostly like mono unless you do something.  Still need apps that allow RACE 
sound to be output while a game or video is on the screen.
 
New pictures, link, etc.
 
Ralph Glasgal
www.ambiophonics.org
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Dave Malham wrote:




On 18/07/2011 19:34, Stefan Schreiber wrote:


Jörn Nettingsmeier wrote:


On 07/18/2011 06:18 PM, Stefan Schreiber wrote:






So we’re taking advantage of
what we learned there to create this feeling that things are being
projected into space in the D axis, the depth axis.







the what?

so this is 4d spacetime, right? x, y, z, and d :)  now this funny 
drone noise, is that minkowski spinning in his grave?




Careful, here I differ!

In a parametric approach, d makes a lot of sense. It is not clear 
from the interview < how > the distance cues are reproduced, agreed.




And I (re)differ. In a parametric approach it makes no sense (and may 
even be harmful) to define a parameter twice, as this implies. If we 
assume the _actually_ mean distance when they talk of depth, then that 
is already given by the audio object's position w.r.t. the 
listener.Anything else is just mumbo-jumbo..or, rather, it is 
mistaking the affect of having audio objects (including early 
reflections and so on) presented at many different distances, rather 
than at similar apparent distances, for something that is real and 
physical.



Agreed, I was wrong on this.



Music representation according to this approach is clearly 
five-dimensional (x,y,z, d and t!), so they call this "multidimensial 
audio"/MDA...O:-)  :-)


You've forgotten timbre,  loudness, rhythm and so on..hang on, isn't 
getting to sound a bit like string theory (and if it is, ain't that 
going to annoy the wind and percussion sections...).  Sorry, 
sorry, couldn't resist.



Why are you sorry? I was kidding...   Some physical theories are 
actually using (just) 5 dimensions. String theory requires more, but I 
am very unsure if string theory is really "hot" at the moment... Had 
recently a long discussion with a French cosmologist after a concert. 
All this dark energy/dark matter stuff  and the missing particles at 
CERN might be pretty unrelated to string theory, right?! Anyway, I 
actually learned that dark energy is not the same as inflation, even if 
this is not clear from the start... You never know, though.   String 
theory? This  is so ridiculously 80s, come on... :-D










However, X-talk cancelling techniques would require close speakers.




i'm not sure about this. from what i've heard, rwth aachen are 
running a CAVE with head tracking and binaural feeds delivered by a 
cube of speakers (as that is the only layout that wouldn't interfere 
too much with their screen configuration). no idea how exactly they 
do it, but there should be some papers out there. iirc they can even 
accomodate more than one listener. haven't heard it, though.





See 
http://darwin.bth.rwth-aachen.de/opus3/volltexte/2009/2713/pdf/Assenmacher_Ingo.pdfts";. 




Thanks, I will look into this when I have more time.

However, if they can't track more than one listener, the system is DOA. 
Nice research, but keep developping something for a more social experience.


...



Don't think he's saying it's vapourware - just that it sounds like 
snake-oil sales talk...but a truly modern version of this should 
include the "q" word in it at least once (well, strictly speaking, it 
would be superimposed an infinite number of times, but would collapse 
to a single state on being read)


My opinion: It is the right time to introduce some improved surround 
system into the market, at least in the cinema area there seems to be 
real demand.
Scientifically, we should have gathered enough knowledge to be able 
to do so, by now.




Agreed (and so, apparently, do the BBC and many others)



You know my opinion: They should introduce some form of sound field 
approach into the supposed "general" 3D audio standard, if there is a 
standard at all. Say Ambisonics up to 3rd order, F-M higher order format.


Even more important will be to design relatively simple systems which 
are able to reproduce surround sound and 3D audio at home, or even in 
cinemas. I think they should consider both headphone and loudspeaker 
systems, from the start. (If some systems are not "complete", say 3D7.1, 
they still might offer new possibilities.)






Surround is not just about Ambisonics and maybe WFS, yet again.



True - but they are ones that work and are well established.

Dave

See above: I believe that the reproduction side is actually more 
important. If you have found some convincing solution on the 
reproduction side, the "coding" of 3D audio is a solved issue. On the 
other hand, if nobody actually can hear to the beauty of sound fields or 
fast-moving audio objects...


I actually don't like the parametric/object approach a lot, but for some 
reasons they might be able to define at least < some > standard. To have 
some standard is better than not to agree on anything.


What is more interesting to me is < how > SRS is actually reproducing 3D 
and distance cues.


Again I would like to refer to the article which was cited! There seems 
to be a 

Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Dave Malham]

On 18/07/2011 19:34, Stefan Schreiber wrote:

Jörn Nettingsmeier wrote:


On 07/18/2011 06:18 PM, Stefan Schreiber wrote:





So we’re taking advantage of
what we learned there to create this feeling that things are being
projected into space in the D axis, the depth axis.






the what?

so this is 4d spacetime, right? x, y, z, and d :)  now this funny drone noise, is that minkowski 
spinning in his grave?



Careful, here I differ!

In a parametric approach, d makes a lot of sense. It is not clear from the interview < how > the 
distance cues are reproduced, agreed.




And I (re)differ. In a parametric approach it makes no sense (and may even be harmful) to define a 
parameter twice, as this implies. If we assume the _actually_ mean distance when they talk of depth, 
then that is already given by the audio object's position w.r.t. the listener.Anything else is just 
mumbo-jumbo..or, rather, it is mistaking the affect of having audio objects (including early 
reflections and so on) presented at many different distances, rather than at similar apparent 
distances, for something that is real and physical.


Music representation according to this approach is clearly five-dimensional (x,y,z, d and t!), so 
they call this "multidimensial audio"/MDA...O:-)  :-)


You've forgotten timbre,  loudness, rhythm and so on..hang on, isn't getting to sound a bit like 
string theory (and if it is, ain't that going to annoy the wind and percussion sections...).  
Sorry, sorry, couldn't resist.







However, X-talk cancelling techniques would require close speakers.



i'm not sure about this. from what i've heard, rwth aachen are running a CAVE with head tracking 
and binaural feeds delivered by a cube of speakers (as that is the only layout that wouldn't 
interfere too much with their screen configuration). no idea how exactly they do it, but there 
should be some papers out there. iirc they can even accomodate more than one listener. haven't 
heard it, though.




See 
http://darwin.bth.rwth-aachen.de/opus3/volltexte/2009/2713/pdf/Assenmacher_Ingo.pdfts";.
of course you could also say "we are harnessing ultrasound-triggered ectoplasm for real 4-d sound 
projectiong using our proprietary one-more-dimension-than-your-mum technology". yawn.



Disagree, and strongly! They are demonstrating their technology, this is not 
about vaporware.


Don't think he's saying it's vapourware - just that it sounds like snake-oil sales talk...but a 
truly modern version of this should include the "q" word in it at least once (well, strictly 
speaking, it would be superimposed an infinite number of times, but would collapse to a single state 
on being read)


My opinion: It is the right time to introduce some improved surround system into the market, at 
least in the cinema area there seems to be real demand.

Scientifically, we should have gathered enough knowledge to be able to do so, 
by now.



Agreed (and so, apparently, do the BBC and many others)



Surround is not just about Ambisonics and maybe WFS, yet again.


True - but they are ones that work and are well established.

Dave

--
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/* York YO10 5DD */
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Dave Malham]

On 18/07/2011 19:01, Fons Adriaensen wrote:

On Mon, Jul 18, 2011 at 07:27:26PM +0200, Jörn Nettingsmeier wrote:




I hope you managed to clean your keyboard. It could have
happened to me as well...

I was fortunately luck enough not to have brewed any yet this morning...

Dave

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/* Heslington  Fax   01904 432450*/
/* York YO10 5DD */
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Dave Malham]

Hi Jörn,
   Saved me some typing - pretty well what I would have said :-)

   Dave

On 18/07/2011 18:27, Jörn Nettingsmeier wrote:

On 07/18/2011 06:18 PM, Stefan Schreiber wrote:


Now, it turns out that one of the techniques for projecting sound into
space based on the auditory system is something called HRTF, or
head-related transfer functions, where the frequency or spectral
characteristics of a broadband audio signal, like speech or music,
will vary depending on the angle relative to the ear canal. And that’s
because of the structure of the head and the outer ear, and the
shoulders—everything. And by understanding how that changes, we can
take advantage of HRTF to create sounds in three-dimensional space,
from a perception standpoint, that aren’t actually coming from speakers.


Which means that they are probably using HRTF techniques. Because HRTF
is an individual parameter, they would have to use some form of
"standard" HRTF, as long as they don't perform individual measurements.
For me, the interviewer didn't ask the right questions.


quite obviously, the interviewer either doesn't have much insight into surround sound 
psychoacoustics as a whole, or he's deliberately playing dumb for the (dubious) benefit of his 
readers.



And again, that’s not just amplitude.


master of suspense. to the uninitiated, this wording implies high magic. to the slightly more 
initiated, the word "phase" begins to glow in deep blue letters on the wall, and we have read so 
many amazing things in our hifi magazines about phase, and our friends in the pub don't understand 
it.



So we’re taking advantage of
what we learned there to create this feeling that things are being
projected into space in the D axis, the depth axis.




the what?

so this is 4d spacetime, right? x, y, z, and d :)  now this funny drone noise, is that minkowski 
spinning in his grave?



This < might > be something new, and indeed difficult to obtain with 5.1
or (classical) Ambisonics. (If at all.)


ambisonics is about recreating a sound field (for many listeners). head-tracked binaural (whether 
fed over loudspeakers or headphones) is a single-listener thing.
any cues that will work without head tracking for more than a single person with known orientation 
in the room can be tacked to ambisonics just as well.



However, X-talk cancelling techniques would require close speakers.


i'm not sure about this. from what i've heard, rwth aachen are running a CAVE with head tracking 
and binaural feeds delivered by a cube of speakers (as that is the only layout that wouldn't 
interfere too much with their screen configuration). no idea how exactly they do it, but there 
should be some papers out there. iirc they can even accomodate more than one listener. haven't 
heard it, though.



What I heard that day at SRS was a witch’s brew of breakthrough audio
technologies, a combination of new psychoacoustic depth-rendering
techniques applied through the filter of a game-changing approach to
mixing movie soundtracks that SRS calls Multi-dimensional Audio, or
MDA. Together, they form the basis of CircleCinema 3D, a feature that
will begin appearing in flat-panel HDTVs and soundbars from SRS
licensees in 2012, and perhaps later, in A/V receivers.


this is gibberish.


But the coding of depth cues seems to be something new, and if this
works, it is really impressing.


actually, i don't see that happening for more than one person, without head 
tracking.


P.S.: The next surround system has to be independent of speaker
configurations, and to include the 3D/"sphere" aspect. If you can
reproduce distance cues, even better.


distance cues are mostly gimmickry in my opinion. you can fake distance in a number of ways, but 
most are really dependent on the spectrum and envelope of the program material. most aspects of 
distance encoding are also orthogonal to most surround techniques, which means they can be added 
at will, today. they don't even necessitate a fancy new name.


you could just say "i'm doing crosstalk-cancelled binaual delivery via speakers using near-field 
hrtfs as described by menzies and others", or you could say "i'm using vector-base amplitude 
panning of anechoic audio objects as introduced by pulkki, combined with room synthesis based on 
well-known algorithms a, b, and c, some lowpass to mimic air absorption and adaptive resampling 
delay to obtain doppler shifts".


of course you could also say "we are harnessing ultrasound-triggered ectoplasm for real 4-d sound 
projectiong using our proprietary one-more-dimension-than-your-mum technology". yawn.


it's so friggin' hard to make the walls of the listening room disappear (with _any_ surround 
technique) that i don't see how the majority of consumers would ever respond to distance cues 
properly, with the exception of some bumblebee-in-your-ear tricks or depth effects mediated by 
visuals. the former are often limited to very specific content, and for the latter, if you have 
visual

Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Jörn Nettingsmeier wrote:


On 07/18/2011 06:18 PM, Stefan Schreiber wrote:





Which means that they are probably using HRTF techniques. Because HRTF
is an individual parameter, they would have to use some form of
"standard" HRTF, as long as they don't perform individual measurements.
For me, the interviewer didn't ask the right questions.



quite obviously, the interviewer either doesn't have much insight into 
surround sound psychoacoustics as a whole, or he's deliberately 
playing dumb for the (dubious) benefit of his readers.



Jörn, yes, but I tried to distinguish between the interviewer and the 
technique which is actually reviewed. ..





And again, that’s not just amplitude.




master of suspense. to the uninitiated, this wording implies high 
magic. to the slightly more initiated, the word "phase" begins to glow 
in deep blue letters on the wall, and we have read so many amazing 
things in our hifi magazines about phase, and our friends in the pub 
don't understand it.



Right you are ;-) , even completey right, but see my first commentary above.




So we’re taking advantage of
what we learned there to create this feeling that things are being
projected into space in the D axis, the depth axis.






the what?

so this is 4d spacetime, right? x, y, z, and d :)  now this funny 
drone noise, is that minkowski spinning in his grave?



Careful, here I differ!

In a parametric approach, d makes a lot of sense. It is not clear from 
the interview < how > the distance cues are reproduced, agreed.


Music representation according to this approach is clearly 
five-dimensional (x,y,z, d and t!), so they call this "multidimensial 
audio"/MDA...O:-)  :-)





This < might > be something new, and indeed difficult to obtain with 5.1
or (classical) Ambisonics. (If at all.)



ambisonics is about recreating a sound field (for many listeners). 
head-tracked binaural (whether fed over loudspeakers or headphones) is 
a single-listener thing.
any cues that will work without head tracking for more than a single 
person with known orientation in the room can be tacked to ambisonics 
just as well.



Ambisonics 1st order doesn't reproduce close distance. And maybe it is 
just for one or two listeners. We have to be fair...





However, X-talk cancelling techniques would require close speakers.



i'm not sure about this. from what i've heard, rwth aachen are running 
a CAVE with head tracking and binaural feeds delivered by a cube of 
speakers (as that is the only layout that wouldn't interfere too much 
with their screen configuration). no idea how exactly they do it, but 
there should be some papers out there. iirc they can even accomodate 
more than one listener. haven't heard it, though.



Heinrich Hertz Institut (Berlin) does reproduction of 3D video without 
glasses, while they are tracking observer positions.
Even the XBox might track players, so what?   (Kinect, distance cues 
quite directly via IR camera, if I remember well.)





What I heard that day at SRS was a witch’s brew of breakthrough audio
technologies, a combination of new psychoacoustic depth-rendering
techniques applied through the filter of a game-changing approach to
mixing movie soundtracks that SRS calls Multi-dimensional Audio, or
MDA. Together, they form the basis of CircleCinema 3D, a feature that
will begin appearing in flat-panel HDTVs and soundbars from SRS
licensees in 2012, and perhaps later, in A/V receivers.




this is gibberish.



Look, he is just a journalist, not a sursound-trained suround 
scientist...8-)
One technique journalist I know has told me that he plans to visit SRS 
when he is next time in LA, which will be soonly. The interview should 
include better question, he already knows...





But the coding of depth cues seems to be something new, and if this
works, it is really impressing.



actually, i don't see that happening for more than one person, without 
head tracking.



Very unclear, indeed. Somebody has to review the approach from a more 
technical point of view!





P.S.: The next surround system has to be independent of speaker
configurations, and to include the 3D/"sphere" aspect. If you can
reproduce distance cues, even better.



distance cues are mostly gimmickry in my opinion. you can fake 
distance in a number of ways, but most are really dependent on the 
spectrum and envelope of the program material. most aspects of 
distance encoding are also orthogonal to most surround techniques, 
which means they can be added at will, today. they don't even 
necessitate a fancy new name.



Ok. So just < do > this in a commecial system?!

But again, if they design some parametric or "audio object" based 
system, it is natural to add some distance parameter. (In 3D video, the 
parallel approach would be "2D and depth". It is pretty natural and 
efficient, although there are some limits in accuiracy.)




you could just say "i'm doing crosstalk-cancelled binaual delivery via 
speakers usin

Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Fons Adriaensen]

On Mon, Jul 18, 2011 at 07:27:26PM +0200, Jörn Nettingsmeier wrote:

> 

Now _that_ would be an interesting case: how to render this
so it appears to be the listener's nose doing the work...

I hope you managed to clean your keyboard. It could have
happened to me as well...

Ciao,

-- 
FA

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Jörn Nettingsmeier]

On 07/18/2011 06:18 PM, Stefan Schreiber wrote:


Now, it turns out that one of the techniques for projecting sound into
space based on the auditory system is something called HRTF, or
head-related transfer functions, where the frequency or spectral
characteristics of a broadband audio signal, like speech or music,
will vary depending on the angle relative to the ear canal. And that’s
because of the structure of the head and the outer ear, and the
shoulders—everything. And by understanding how that changes, we can
take advantage of HRTF to create sounds in three-dimensional space,
from a perception standpoint, that aren’t actually coming from speakers.


Which means that they are probably using HRTF techniques. Because HRTF
is an individual parameter, they would have to use some form of
"standard" HRTF, as long as they don't perform individual measurements.
For me, the interviewer didn't ask the right questions.


quite obviously, the interviewer either doesn't have much insight into 
surround sound psychoacoustics as a whole, or he's deliberately playing 
dumb for the (dubious) benefit of his readers.



And again, that’s not just amplitude.


master of suspense. to the uninitiated, this wording implies high magic. 
to the slightly more initiated, the word "phase" begins to glow in deep 
blue letters on the wall, and we have read so many amazing things in our 
hifi magazines about phase, and our friends in the pub don't understand it.



So we’re taking advantage of
what we learned there to create this feeling that things are being
projected into space in the D axis, the depth axis.




the what?

so this is 4d spacetime, right? x, y, z, and d :)  now this funny drone 
noise, is that minkowski spinning in his grave?



This < might > be something new, and indeed difficult to obtain with 5.1
or (classical) Ambisonics. (If at all.)


ambisonics is about recreating a sound field (for many listeners). 
head-tracked binaural (whether fed over loudspeakers or headphones) is a 
single-listener thing.
any cues that will work without head tracking for more than a single 
person with known orientation in the room can be tacked to ambisonics 
just as well.



However, X-talk cancelling techniques would require close speakers.


i'm not sure about this. from what i've heard, rwth aachen are running a 
CAVE with head tracking and binaural feeds delivered by a cube of 
speakers (as that is the only layout that wouldn't interfere too much 
with their screen configuration). no idea how exactly they do it, but 
there should be some papers out there. iirc they can even accomodate 
more than one listener. haven't heard it, though.



What I heard that day at SRS was a witch’s brew of breakthrough audio
technologies, a combination of new psychoacoustic depth-rendering
techniques applied through the filter of a game-changing approach to
mixing movie soundtracks that SRS calls Multi-dimensional Audio, or
MDA. Together, they form the basis of CircleCinema 3D, a feature that
will begin appearing in flat-panel HDTVs and soundbars from SRS
licensees in 2012, and perhaps later, in A/V receivers.


this is gibberish.


But the coding of depth cues seems to be something new, and if this
works, it is really impressing.


actually, i don't see that happening for more than one person, without 
head tracking.



P.S.: The next surround system has to be independent of speaker
configurations, and to include the 3D/"sphere" aspect. If you can
reproduce distance cues, even better.


distance cues are mostly gimmickry in my opinion. you can fake distance 
in a number of ways, but most are really dependent on the spectrum and 
envelope of the program material. most aspects of distance encoding are 
also orthogonal to most surround techniques, which means they can be 
added at will, today. they don't even necessitate a fancy new name.


you could just say "i'm doing crosstalk-cancelled binaual delivery via 
speakers using near-field hrtfs as described by menzies and others", or 
you could say "i'm using vector-base amplitude panning of anechoic audio 
objects as introduced by pulkki, combined with room synthesis based on 
well-known algorithms a, b, and c, some lowpass to mimic air absorption 
and adaptive resampling delay to obtain doppler shifts".


of course you could also say "we are harnessing ultrasound-triggered 
ectoplasm for real 4-d sound projectiong using our proprietary 
one-more-dimension-than-your-mum technology". yawn.


it's so friggin' hard to make the walls of the listening room disappear 
(with _any_ surround technique) that i don't see how the majority of 
consumers would ever respond to distance cues properly, with the 
exception of some bumblebee-in-your-ear tricks or depth effects mediated 
by visuals. the former are often limited to very specific content, and 
for the latter, if you have visuals, then like it or not, mono is 
totally adequate and the brain will do the rest (exaggerated, but only 
very slightly).



--
J

Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Hi David...

As you are a knowledgeable expert on this stuff   :-) , I would like to 
take the discussion of this article/interview to a higher level...



The interesting part of the interview is on the 2nd page:

http://www.hometheater.com/content/tech-spotlight-page-2


But with the full evolution to MDA, the creator can tell us, say, we 
want objects panned not just around a twodimensional plane, around the 
edges like you can do with traditional surround, but also around 
interior points, immersive points. Even with 7.1 today, the sound is 
still in a two-dimensional plane, and it still clings to the speakers 
and to the walls—you don’t get the feeling that you’re immersed in the 
soundfield.



So why not use what we know about the hearing system to create this 
perception of three-dimensional space and emergence without a lot of 
boxes hanging around the room? That defines the whole theory of 
psychoacoustics: Let’s use the hearing system directly, rather than 
indirectly with speakers all over the place. 



Now, it turns out that one of the techniques for projecting sound into 
space based on the auditory system is something called HRTF, or 
head-related transfer functions, where the frequency or spectral 
characteristics of a broadband audio signal, like speech or music, 
will vary depending on the angle relative to the ear canal. And that’s 
because of the structure of the head and the outer ear, and the 
shoulders—everything. And by understanding how that changes, we can 
take advantage of HRTF to create sounds in three-dimensional space, 
from a perception standpoint, that aren’t actually coming from speakers. 



Which means that they are probably using HRTF techniques. Because HRTF 
is an  individual parameter, they would have to use some form of 
"standard" HRTF, as long as they don't perform individual measurements. 
For me, the interviewer didn't ask the right questions. To be fair, the 
interviewer can't have sufficient scientific/technical background if he 
did not read every single contribution on the sursound list during many 
laborious years...:-D


The next thing that you heard with CC3D was another psychoacoustic 
phenomenon that we kind of discovered last year about what sounds do 
when they come closer versus moving farther away. And we found that we 
were able to simulate something that normally can’t be done with 
traditional surround sound, which is proximity. 



And again, that’s not just amplitude. So we’re taking advantage of 
what we learned there to create this feeling that things are being 
projected into space in the D axis, the depth axis. 



This < might > be something new, and indeed difficult to obtain with 5.1 
or (classical) Ambisonics. (If at all.)


So, when you have this two-speaker concept, this 
minimal-number-of-speakers concept, you can create a much more 
immersive soundfield because it’s matching playback to the human 
ear-brain system, to the perception system, in a much better way than 
you can when you’re just simulating surround by putting speakers 
around the room. 



But as 2 speakers are too limited if you want to hear anything real (or 
at least "non-gimmick") from behind...


So what we’re working on now is essentially a multichannel or 5.1 
version of the twochannel system that you heard. You can have speakers 
back there, as long as you treat all the speakers with the same kind 
of technology to maintain this immersion. 



However, X-talk cancelling techniques would require close speakers. Even 
if you consider that you have three frontspeakers in 5.1 (C, L, R), I 
would think that C doesn't really matter a lot, and you still have to 
consider 60º X-talk cancellation between L and R.


Or is this  a different 5.1 system, say Ambiophonics with 2 or 3 
surround speakers?


What I heard that day at SRS was a witch’s brew of breakthrough audio 
technologies, a combination of new psychoacoustic depth-rendering 
techniques applied through the filter of a game-changing approach to 
mixing movie soundtracks that SRS calls Multi-dimensional Audio, or 
MDA. Together, they form the basis of CircleCinema 3D, a feature that 
will begin appearing in flat-panel HDTVs and soundbars from SRS 
licensees in 2012, and perhaps later, in A/V receivers. 



If we speak about flat-panel HDTVs, this should be an X-talk elimination 
based system.


You can't offer receivers if there is not an agreed surround standard 
yet(supposedly based on audio objects).



The system might be a kind of combination of Mpeg-4 (audio objects) , 
soundfield techniques and X-talk elimination.


But the coding of depth cues seems to be  something new, and if this 
works, it is really impressing.



Now, I just wanted to dispute the claim that SRS isn't offering anything 
new at all. Probably they do, at least they are trying to apply some 
combination of existing technologies into the maketplace.



Best regards

Stefan

P.S.: The next surround system has to be independent of spe

Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Dave Malham]

Hi Jörn and Bearcat

On 16/07/2011 06:56, Jörn Nettingsmeier wrote:

On 07/16/2011 01:32 AM, "Bearcat M. Şandor" wrote:

I found that review/interview of the 2 channel surround sound i was
referring to earlier:

http://www.hometheater.com/content/tech-spotlight-srs-future-surround

The first copy i saw didn't have the 2nd page. In it it's explained that
you'd need speakers behind you to hear things behind you.



Hmm, reading through this, it seems that basically they've discovered MPEG4 Spatial Audio Object 
Coding :-)



They speak of proximity, of things moving closer and further away from
your face. Can ambisonics do that as well?


classical ambisonics doesn't really do that. on good recordings, you will get a very nice sense of 
distance, but that is due to distance cues which are more or less independent of ambisonics (any 
good recording method can do it).
what you definitely won't get (with any order less than "ridiculously high") are sources closer 
than the ring of speakers.


Whilst I agree that you can't generally get stationary audio objects closer than the radius of the 
speakers on low order systems (currently, only high order Ambisonic systems, WFS or crosstalk 
cancelled binaural systems can do that - oh, and the various ultrasound based speakers), you can get 
reasonably quickly moving objects to appear to pass close by, especially if the acoustic of the 
playback space is dead relative to the reproduced space, provided you give enough cues (particularly 
early reflection patterns and proximity effect) in the soundscape to override the conflicting 
playback space cues. Whilst this also occurs with any decent replay methodology,  it is easier with 
Ambisonics because (I suspect) of the fact that there is always more than one speaker producing 
sound, so the local space cues conflict not just with the soundscape cues, but also each other, 
weakening the perceptual effects of the local cues.


Dave

--
 These are my own views and may or may not be shared by my employer
/*/
/* Dave Malham   http://music.york.ac.uk/staff/research/dave-malham/ */
/* Music Research Centre */
/* Department of Music"http://music.york.ac.uk/";   */
/* The University of York  Phone 01904 432448*/
/* Heslington  Fax   01904 432450*/
/* York YO10 5DD */
/* UK   'Ambisonics - Component Imaging for Audio'   */
/*"http://www.york.ac.uk/inst/mustech/3d_audio/"; */
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Jörn Nettingsmeier]

On 07/16/2011 01:32 AM, "Bearcat M. Şandor" wrote:

I found that review/interview of the 2 channel surround sound i was
referring to earlier:

http://www.hometheater.com/content/tech-spotlight-srs-future-surround

The first copy i saw didn't have the 2nd page. In it it's explained that
you'd need speakers behind you to hear things behind you.

They speak of proximity, of things moving closer and further away from
your face. Can ambisonics do that as well?


classical ambisonics doesn't really do that. on good recordings, you 
will get a very nice sense of distance, but that is due to distance cues 
which are more or less independent of ambisonics (any good recording 
method can do it).
what you definitely won't get (with any order less than "ridiculously 
high") are sources closer than the ring of speakers.



--
Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487

Meister für Veranstaltungstechnik (Bühne/Studio)
Tonmeister VDT

http://stackingdwarves.net

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Bearcat M. Şandor]

I found that review/interview of the 2 channel surround sound i was
referring to earlier:

http://www.hometheater.com/content/tech-spotlight-srs-future-surround

The first copy i saw didn't have the 2nd page. In it it's explained that
you'd need speakers behind you to hear things behind you.

They speak of proximity, of things moving closer and further away from
your face. Can ambisonics do that as well?

-- 
Bearcat M. Şandor
Cell: 406.210.3500
Jabber/xmpp/gtalk/email: bear...@feline-soul.net
MSN: bearcatsan...@hotmail.com
Yahoo: bearcatsandor
AIM: bearcatmsandor


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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[seberbach]

Yes, but a Wii multi-axis remote containing the needed motion tracking 
technology is quite affordable, while the head tracker headphone products cited 
in the recent post here are very competent but far too expensive to gain wide 
consumer acceptance.

I think the problem would be solved when a gaming company, or anybody with a 
potential market application large enough is motivated to invest in development 
of a lower priced but competently designed product.

I once bid several hundred dollars for a Sony head tracker wireless headphone 
set (which allows multiple simultaneous users listening to the same music disk) 
and lost the auction.  The product failed to catch on in the marketplace, but 
people still snap up any of these which become available used for a very high 
price.

 

 


 

 

-Original Message-
From: Jörn Nettingsmeier 
To: sursound@music.vt.edu
Sent: Mon, Jul 11, 2011 8:01 am
Subject: Re: [Sursound] the recent 2-channel 3D sound formats and their 
viability for actual 360 degree sound


On 07/11/2011 12:39 AM, Stefan Schreiber wrote: 
 
> With all these efforts, why is actually nobody just marketing a 
> headphone solution with head-tracking? 
 
smyth research makes one (called the realizer), or there's the beyerdynamic 
headzone. 
 
-- Jörn Nettingsmeier 
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487 
 
Meister für Veranstaltungstechnik (Bühne/Studio) 
Tonmeister VDT 
 
http://stackingdwarves.net 
 
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[seberbach]

It (partial sphere coverage) is useful "enough" if the partial sphere "covers" 
the positions of the acoustic objects being recorded and reproduced.
The most important property being reproduced is not the accuracy and precision 
of the static positioning, it is the dynamic spatial articulation
in the rendered sonic image which realistically conveys artistic creativity to 
the audience through the audibility of movement.

 

 


 

 

-Original Message-
From: Tom Jordaan 
To: Surround Sound discussion group 
Sent: Tue, Jul 12, 2011 9:24 am
Subject: Re: [Sursound] the recent 2-channel 3D sound formats and their 
viability for actual 360 degree sound


On Tue, 12 Jul 2011 01:56:08 +0100, Stefan Schreiber  
wrote: 
 
> The minimum for surround with height is 8 speakers, for Ambisonics 1st > 
> order. If the sphere is full-sphere (and not half-sphere), you probably > 
> need 12+ speakers, although I suspect there could be a solution with > less 
> speakers than 12. (Feeback welcome...) 
> 
> Some have tried to reproduce "some" height information via a 7.1 layout. > 
> (And even 5.1, but here there are severe limitations.) 
 
Can anyone shed further light on the usefulness of the 3D 7.1 layout that 
Richard Furse's player offers? Possibly only a segment of a sphere, rather 
than full sphere, but is it useful *enough*? 
 
--"In human terms, the future was bright, bright red." 
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Jörn Nettingsmeier wrote:


On 07/12/2011 05:39 PM, Stefan Schreiber wrote:


Jörn Nettingsmeier wrote:


there is an AES paper by simon goodwin that deals with this layout:
www.codemasters.com/research/3D_sound_for_3D_games.pdf

the rationale is that you can deliver a pre-decoded stream over the
eight channels of a hdmi link and obtain some sort of 3D, while
retaining meaningful values of spouse acceptance factor :)

here's another very interesting study about the gaming market, and why
or why not it might be a spearhead for spatial audio at home:
http://www.codemasters.com/research/HowPlayersListen.pdf



Links don't work, "access denied".



403 - Forbidden: Access is denied.


You do not have permission to view this directory or page using
the credentials that you supplied.



(snobby) I never will share valuable research with the Codemaster guys
who don't share... :-D



both links work for me... ping me off-list if you still can't get 
them, and i'll send them to you in private mail.




Yes, later both links worked. (No wrongdoing from my part, I put the 
links into different browsers, and before nothing worked.)


Thanks,

Stefan


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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[dave . malham]

Both links work for me, too.

  Dave (from home)

On Jul 12 2011, Jörn Nettingsmeier wrote:


On 07/12/2011 05:39 PM, Stefan Schreiber wrote:

Jörn Nettingsmeier wrote:


there is an AES paper by simon goodwin that deals with this layout:
www.codemasters.com/research/3D_sound_for_3D_games.pdf

the rationale is that you can deliver a pre-decoded stream over the
eight channels of a hdmi link and obtain some sort of 3D, while
retaining meaningful values of spouse acceptance factor :)

here's another very interesting study about the gaming market, and why
or why not it might be a spearhead for spatial audio at home:
http://www.codemasters.com/research/HowPlayersListen.pdf



Links don't work, "access denied".


403 - Forbidden: Access is denied.


You do not have permission to view this directory or page using
the credentials that you supplied.



(snobby) I never will share valuable research with the Codemaster guys
who don't share... :-D


both links work for me... ping me off-list if you still can't get them, 
and i'll send them to you in private mail.







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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Martin Leese]

"Tom Jordaan"  wrote:

> On Tue, 12 Jul 2011 01:56:08 +0100, Stefan Schreiber
>  wrote:
>> The minimum for surround with height is 8 speakers, for Ambisonics 1st
>> order. If the sphere is full-sphere (and not half-sphere), you probably
>> need 12+ speakers, although I suspect there could be a solution with
>> less speakers than 12. (Feeback welcome...)
>>
>> Some have tried to reproduce "some" height information via a 7.1 layout.
>> (And even 5.1, but here there are severe limitations.)
>
> Can anyone shed further light on the usefulness of the 3D 7.1 layout that
> Richard Furse's player offers? Possibly only a segment of a sphere, rather
> than full sphere, but is it useful *enough*?

The minimum for Ambisonic surround with
height is 6 speakers.  This is according to:

M.A. Gerzon, "Periphony: With-Height Sound
Reproduction", J. Audio Eng. Soc., vol. 21,
pp. 2-10 (1973 Jan./Feb.)
(A highly mathematical account of general
with-height reproduction systems. Includes the
fundamental theory of with-height directional
encoding systems).

The speakers are placed on the faces of a
cube, or at the vertices of an octahedron
(depending on how you choose to think about
these things).  Simon Goodwin's 3D7.1 is just
such a full-sphere layout (with the addition of
a seventh centre-front speaker at head height).

I have never used 3D7.1, so cannot comment
on its usefulness.

Regards,
Martin
-- 
Martin J Leese
E-mail: martin.leese  stanfordalumni.org
Web: http://members.tripod.com/martin_leese/
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Jörn Nettingsmeier]

On 07/12/2011 05:39 PM, Stefan Schreiber wrote:

Jörn Nettingsmeier wrote:


there is an AES paper by simon goodwin that deals with this layout:
www.codemasters.com/research/3D_sound_for_3D_games.pdf

the rationale is that you can deliver a pre-decoded stream over the
eight channels of a hdmi link and obtain some sort of 3D, while
retaining meaningful values of spouse acceptance factor :)

here's another very interesting study about the gaming market, and why
or why not it might be a spearhead for spatial audio at home:
http://www.codemasters.com/research/HowPlayersListen.pdf



Links don't work, "access denied".


403 - Forbidden: Access is denied.


You do not have permission to view this directory or page using
the credentials that you supplied.



(snobby) I never will share valuable research with the Codemaster guys
who don't share... :-D


both links work for me... ping me off-list if you still can't get them, 
and i'll send them to you in private mail.




--
Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487

Meister für Veranstaltungstechnik (Bühne/Studio)
Tonmeister VDT

http://stackingdwarves.net

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Jörn Nettingsmeier wrote:


On 07/12/2011 03:24 PM, Tom Jordaan wrote:


On Tue, 12 Jul 2011 01:56:08 +0100, Stefan Schreiber
 wrote:


The minimum for surround with height is 8 speakers, for Ambisonics 1st
order. If the sphere is full-sphere (and not half-sphere), you
probably need 12+ speakers, although I suspect there could be a
solution with less speakers than 12. (Feeback welcome...)

Some have tried to reproduce "some" height information via a 7.1
layout. (And even 5.1, but here there are severe limitations.)



Can anyone shed further light on the usefulness of the 3D 7.1 layout 
that
Richard Furse's player offers? Possibly only a segment of a sphere, 
rather

than full sphere, but is it useful *enough*?



there is an AES paper by simon goodwin that deals with this layout:
www.codemasters.com/research/3D_sound_for_3D_games.pdf

the rationale is that you can deliver a pre-decoded stream over the 
eight channels of a hdmi link and obtain some sort of 3D, while 
retaining meaningful values of spouse acceptance factor :)


here's another very interesting study about the gaming market, and why 
or why not it might be a spearhead for spatial audio at home:

http://www.codemasters.com/research/HowPlayersListen.pdf


Links don't work, "access denied".  



403 - Forbidden: Access is denied.


  You do not have permission to view this directory or page using
  the credentials that you supplied.



(snobby) I never will share valuable research with the Codemaster guys 
who don't share... :-D



Best,

Stefan
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Jörn Nettingsmeier]

On 07/12/2011 03:24 PM, Tom Jordaan wrote:

On Tue, 12 Jul 2011 01:56:08 +0100, Stefan Schreiber
 wrote:


The minimum for surround with height is 8 speakers, for Ambisonics 1st
order. If the sphere is full-sphere (and not half-sphere), you
probably need 12+ speakers, although I suspect there could be a
solution with less speakers than 12. (Feeback welcome...)

Some have tried to reproduce "some" height information via a 7.1
layout. (And even 5.1, but here there are severe limitations.)


Can anyone shed further light on the usefulness of the 3D 7.1 layout that
Richard Furse's player offers? Possibly only a segment of a sphere, rather
than full sphere, but is it useful *enough*?


there is an AES paper by simon goodwin that deals with this layout:
www.codemasters.com/research/3D_sound_for_3D_games.pdf

the rationale is that you can deliver a pre-decoded stream over the 
eight channels of a hdmi link and obtain some sort of 3D, while 
retaining meaningful values of spouse acceptance factor :)


here's another very interesting study about the gaming market, and why 
or why not it might be a spearhead for spatial audio at home:

http://www.codemasters.com/research/HowPlayersListen.pdf


--
Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487

Meister für Veranstaltungstechnik (Bühne/Studio)
Tonmeister VDT

http://stackingdwarves.net

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Tom Jordaan]

On Tue, 12 Jul 2011 01:56:08 +0100, Stefan Schreiber  
 wrote:


The minimum for surround with height is 8 speakers, for Ambisonics 1st  
order. If the sphere is full-sphere (and not half-sphere), you probably  
need 12+ speakers, although I suspect there could be a solution with  
less speakers than 12. (Feeback welcome...)


Some have tried to reproduce "some" height information via a 7.1 layout.  
(And even 5.1, but here there are severe limitations.)


Can anyone shed further light on the usefulness of the 3D 7.1 layout that
Richard Furse's player offers? Possibly only a segment of a sphere, rather
than full sphere, but is it useful *enough*?

--
"In human terms, the future was bright, bright red."
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Marc Lavallée]

Stefan Schreiber  a écrit :

> > Right. I was speaking of 360 horizontal.  Just to be clear, how
> > many speakers are necessary at minimum for a "full sphere 3D"
> > system? I've been told that a double twisted hex (3 in front, 3 in
> > back at ear level, and 3 in front, 3 in back up high twisted 90
> > degrees from the ear level set) would do it for a total of 12
> > speakers. Or would you need 18 speakers. I've never seen a picture
> > of what a full 3d sphere layout looks like.
> >
> > Bearcat
> 
> 
> The minimum for surround with height is 8 speakers, for Ambisonics
> 1st order. If the sphere is full-sphere (and not half-sphere), you
> probably need 12+ speakers, although I suspect there could be a
> solution with less speakers than 12. (Feeback welcome...)

A possible solution is the layout proposed by Bo-Erik Sandholm:
https://mail.music.vt.edu/mailman/private/sursound/2011-May/040968.html

"It uses 10 channels, it is a hexagon in the horizontal plane with a
speakers at front back. The Z is handled by for speakers, placed where
the 4 hexagon side speakers will end up if the Hexagon is rotated 90
degrees around a axis through the front and back hexagon speakers."

--
Marc
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Bearcat M. Sandor wrote:


On 7/11/2011 8:30 AM, Stefan Schreiber wrote:



However, the "12+ channel" audio system (for Ambisonics?) is a 
caricature, at best. 8 horizontal speakers would be enough for 
Ambisonics 3rd order, for home purposes. 1st order can be reproduced  
with 4 speakers, you really won't need more than 6. Everybody knows 
this...:-)


In this sense, your posting was polemic, because you also knew this. 
Right?



Best regards,

Stefan

P.S.: Unless we speak about "full sphere 3D", and Ambisonics would 
need more speakers. However, the thead topic says "360 degree sound". 
Therefore, 360º horizontal suround sound and "3D sound" has been 
mixed up in the following postings...


Prof. Choueiri's solution requires special speakers and a controlled 
environment, in my understanding. I remain sceptical if the 
peformance of this system will come close to a real surround system, 
which would have to been tested in an objective way. (I have said 
that my critic doesn't refer to Ambiophonics, which is not an 
"extreme XTC for everything" solution. Maybe I am also polemic... 
:-) )


Right. I was speaking of 360 horizontal.  Just to be clear, how many 
speakers are necessary at minimum for a "full sphere 3D" system? I've 
been told that a double twisted hex (3 in front, 3 in back at ear 
level, and 3 in front, 3 in back up high twisted 90 degrees from the 
ear level set) would do it for a total of 12 speakers. Or would you 
need 18 speakers. I've never seen a picture of what a full 3d sphere 
layout looks like.


Bearcat



The minimum for surround with height is 8 speakers, for Ambisonics 1st 
order. If the sphere is full-sphere (and not half-sphere), you probably 
need 12+ speakers, although I suspect there could be a solution with 
less speakers than 12. (Feeback welcome...)


Some have tried to reproduce "some" height information via a 7.1 layout. 
(And even 5.1, but here there are severe limitations.)



Bye!

Stefan

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Eric Benjamin]

> all of my material that was on there (plus a bit more), and all of John 
>Leonard's,
I hadn't visited your pages in a while.  I particular like the roll-over 
informational photos.

Between your material and John Leonard's material you have Early Music and 
environmental sounds fairly well covered.  Now we need some more variety!

I'll contact you off-list.

Eric



- Original Message 
From: Paul Hodges 
To: Surround Sound discussion group 
Sent: Mon, July 11, 2011 12:45:07 PM
Subject: Re: [Sursound] the recent 2-channel 3D sound formats and their 
viability for actual 360 degree sound

--On 10 July 2011 22:47 +0200 Jörn Nettingsmeier  
wrote:

> the demise of ambisonia.com is lamentable,

Indeed.  But I'd like just to remind people that all of my material that was on 
there (plus a bit more), and all of John Leonard's, and Richard Lee's articles, 
are now available from my site here: <http://ambisonic.info/audio.html> and 
here: <http://ambisonic.info/info.html>.

I will make similar pages for anyone else's stuff if they ask me to.

Paul

-- Paul Hodges


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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Paul Hodges]

--On 10 July 2011 22:47 +0200 Jörn Nettingsmeier 
 wrote:



the demise of ambisonia.com is lamentable,


Indeed.  But I'd like just to remind people that all of my material that 
was on there (plus a bit more), and all of John Leonard's, and Richard 
Lee's articles, are now available from my site here: 
 and here: 
.


I will make similar pages for anyone else's stuff if they ask me to.

Paul

--
Paul Hodges


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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Bearcat M. Sandor]

On 7/11/2011 8:30 AM, Stefan Schreiber wrote:


However, the "12+ channel" audio system (for Ambisonics?) is a 
caricature, at best. 8 horizontal speakers would be enough for 
Ambisonics 3rd order, for home purposes. 1st order can be reproduced  
with 4 speakers, you really won't need more than 6. Everybody knows 
this...:-)


In this sense, your posting was polemic, because you also knew this. 
Right?



Best regards,

Stefan

P.S.: Unless we speak about "full sphere 3D", and Ambisonics would 
need more speakers. However, the thead topic says "360 degree sound". 
Therefore, 360º horizontal suround sound and "3D sound" has been mixed 
up in the following postings...


Prof. Choueiri's solution requires special speakers and a controlled 
environment, in my understanding. I remain sceptical if the peformance 
of this system will come close to a real surround system, which would 
have to been tested in an objective way. (I have said that my critic 
doesn't refer to Ambiophonics, which is not an "extreme XTC for 
everything" solution. Maybe I am also polemic... :-) )
Right. I was speaking of 360 horizontal.  Just to be clear, how many 
speakers are necessary at minimum for a "full sphere 3D" system? I've 
been told that a double twisted hex (3 in front, 3 in back at ear level, 
and 3 in front, 3 in back up high twisted 90 degrees from the ear level 
set) would do it for a total of 12 speakers. Or would you need 18 
speakers. I've never seen a picture of what a full 3d sphere layout 
looks like.


Bearcat
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Bearcat M. Sandor]

On 7/11/2011 8:30 AM, Stefan Schreiber wrote:


However, the "12+ channel" audio system (for Ambisonics?) is a 
caricature, at best. 8 horizontal speakers would be enough for 
Ambisonics 3rd order, for home purposes. 1st order can be reproduced  
with 4 speakers, you really won't need more than 6. Everybody knows 
this...:-)


In this sense, your posting was polemic, because you also knew this. 
Right?



Best regards,

Stefan

P.S.: Unless we speak about "full sphere 3D", and Ambisonics would 
need more speakers. However, the thead topic says "360 degree sound". 
Therefore, 360º horizontal suround sound and "3D sound" has been mixed 
up in the following postings...


Prof. Choueiri's solution requires special speakers and a controlled 
environment, in my understanding. I remain sceptical if the peformance 
of this system will come close to a real surround system, which would 
have to been tested in an objective way. (I have said that my critic 
doesn't refer to Ambiophonics, which is not an "extreme XTC for 
everything" solution. Maybe I am also polemic... :-) )
Right. I was speaking of 360 horizontal.  Just to be clear, how many 
speakers are necessary at minimum for a "full sphere 3D" system? I've 
been told that a double twisted hex (3 in front, 3 in back at ear level, 
and 3 in front, 3 in back up high twisted 90 degrees from the ear level 
set) would do it for a total of 12 speakers. Or would you need 18 
speakers. I've never seen a picture of what a full 3d sphere layout 
looks like.


Bearcat




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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Peter Lennox]

Haven't managed to follow the whole thread, but Dave Worrall's question about 
adaptation to others' pinnae: I think Fred Wightman and Doris Kistler did some 
on this, as did Hofman, Van Riswick and Van Opstal.

The interesting point is that, initially, when listening with others' ears, 
spatial performance is degraded, but over a period of a few weeks (I forget how 
long), performance comes right up to scratch and in a few rare cases, exceeds 
the performance previously demonstrated with listeners' own ears!
The other point was that, after the experiment was over, listeners could go 
right back to listening with their own pinnae, so they'd actually learned a new 
set as well as, not in replacement of, the old set. I've no idea how many sets 
one could learn - could be an important funding bid!
Cheers
ppl

Dr Peter Lennox
School of Technology 
University of Derby, UK
tel: 01332 593155
e: p.len...@derby.ac.uk  

-Original Message-
From: sursound-boun...@music.vt.edu [mailto:sursound-boun...@music.vt.edu] On 
Behalf Of David Worrall
Sent: 09 July 2011 17:20
To: Surround Sound discussion group
Subject: Re: [Sursound] the recent 2-channel 3D sound formats and their 
viability for actual 360 degree sound

[Hello to all - It was good 2 C some of you at ICAD Budapest - and +ve 2 C a 
deal of activity in ambisonics for auditory design.]

On 09/07/2011, at 6:40 AM, Fons Adriaensen wrote:

> On Fri, Jul 08, 2011 at 02:06:37PM -0600, Bearcat M. Sandor wrote:
> 
>> The ear canal is just a tube, so there's no  
>> directionality once the waves are in there.
> 
Two words act as special alarms to me. In finance: "secret" and in 
phenomenology: "just".

The ear canal is no less than "just" a tube than is a didgeridoo at the lips of 
an experienced player.

One can certainly say "the ear canal is tubular" but it is not "just a tube" 
because, for eg,
a) "tube" cannot be assumed to be regular, but arbitrarily complex, is 
arbitrarily flanged at both ends 
b) it has a transverse piece of sound-sensitive skin  (the 'drum'), to which is 
attached other 'stuff'
c) it is part of a head which has a brain in it that is also connected other 
sense receptors, including the vestibular labyrinth etc etc and that it has 
extensive experience using it/them to perceive events in external and internal 
environs, etc etc etc. as well as efference copy-being aware that a movement is 
one's own and not the world's.

Related to (c), does anyone have any reports of empirical experiments on the 
brain's ability to learn/adapt to HRTF encoded signals encoded for 'foreign' 
ears?

David


> "Once they are in there". Which is why you can make things
> work with headphones plus head motion tracking.
> 
> When using speakers, the sound has to get 'in there' first.
> And you are allowed to turn and otherwise move your head,
> so even when e.g. seated you can (and will) explore the sound 
> field around it, and your brain will correlate your movements
> with the changes of the sound entering your ears. So getting
> the right sound 'in there' is not just a matter of recreating
> the sound field at the two points where your ear canals would
> be if your head were clamped into a vise. You have to create
> something matching the field of a real source at least in the
> near vicinity. And it turns out you can't do that without energy 
> arriving from more or less the right direction.
> 
> Ciao,
> 
> -- 
> FA
> 
> ___
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_
Dr David Worrall
Adjunct Research Fellow, Australian National University
david.worr...@anu.edu.au
Board Member, International Community for Auditory Display
Regional Editor, Organised Sound (CUP) 
IT Projects, Music Council of Australia 
worrall.avatar.com.au   sonification.com.au
mca.org.au  musicforum.org.au



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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Bearcat M. Şandor wrote:


On 07/10/2011 11:10 AM, Stefan Schreiber wrote:

 


To clarify a few basic things:

The first poster in this thread (and obviously some other people who
maybe should have known better) are claiming that you could receive a
360º representation via just two (supposedly narrow) front speakers.
   



First poster here. Just to clarify, i didn't claim anything like that. I
just asked if anyone had heard any of these recent 2-channel 3D audio
systems and wondered what they thought of them.  My main point was
whining about the expense of a 12+ channel audio system vs the
possibility of full sphere surround experience with 2 channels.  In
fact, i stated that i had not heard convincing 3D yet. Perhaps a more
forward sound stage, but i've heard good body from my speakers with no
"3D" applied.

 


Ok, fair enough. Your question is/was actually very good.

However, the "12+ channel" audio system (for Ambisonics?) is a 
caricature, at best. 8 horizontal speakers would be enough for 
Ambisonics 3rd order, for home purposes. 1st order can be reproduced  
with 4 speakers, you really won't need more than 6. Everybody knows 
this...:-)


In this sense, your posting was polemic, because you also knew this. Right?


Best regards,

Stefan

P.S.: Unless we speak about "full sphere 3D", and Ambisonics would need 
more speakers. However, the thead topic says "360 degree sound". 
Therefore, 360º horizontal suround sound and "3D sound" has been mixed 
up in the following postings...


Prof. Choueiri's solution requires special speakers and a controlled 
environment, in my understanding. I remain sceptical if the peformance 
of this system will come close to a real surround system, which would 
have to been tested in an objective way. (I have said that my critic 
doesn't refer to Ambiophonics, which is not an "extreme XTC for 
everything" solution. Maybe I am also polemic... :-) )

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Jörn Nettingsmeier wrote:


On 07/11/2011 12:39 AM, Stefan Schreiber wrote:


With all these efforts, why is actually nobody just marketing a
headphone solution with head-tracking?



smyth research makes one (called the realizer), or there's the 
beyerdynamic headzone.




We have discussed the smyth esearch solution some time ago, if I 
remember well.


Beside of this, there seems to be a certain lack of some "popular" 
solution, say "Dolby style" or whatsoever.



Best,

Stefan

P.S.: I believe that Sony did something in this aea, but they didn't 
come to market.(?)


Maybe some of the beancounters decided that this would  not run as a 
viable project... I also don't want to spread rumours, but I believe 
there was "something".


As the research is done, it is more about maketing/innovation. (Old 
style innovation, so to speak. If "content is king", you don't have to 
innovate. Unless the slogan gets out of fashion, of course. < g >)

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Well, unless the amplifier encounters some of the elusive  square 
(freak) waves...  :-D


Stefan

Robert Greene wrote:



No speaker requires a "fast" amplifier,
whatever that means. ALL amplifiers that
are not defective are far faster in any reasonable
sense than any speaker is. Some amps
have a tiny roll off of the extreme top
on account of output networks or the like.
But really this is a nonissue for any serious
purposes.

Robert

On Sun, 10 Jul 2011, Marc Lavall?e wrote:


J?rn Nettingsmeier  a ?crit :


On 07/10/2011 03:41 AM, Marc Lavall?e wrote:


I'm waiting for a pair of
very directional speakers that should (hopefully) help me enjoy
conventional stereo.



then the manger might be for you:
http://manger-msw.de/index.php?language=en

this is a speaker that has been optimized for very good impulse
response behaviour (at the expense of almost everything else).



Then a fast amplifier is required.


in addition to its quick reaction, it's beaming like mad, which means
that it practically eliminates early reflections over a wide band (a
lot wider than conventional dome tweeters). its stereo reproduction
is stunning.



That's the idea: instead of adding tons of acoustic treatment in my
listening room, I prefer to invest in directive speakers.


if you can do with very little efficiency (sorry tube amp fans)



The sensitivity of Manger speakers is about 88dB; that's not so bad.


and don't mind around 10% THD in the low frequencies (which is not as
bad as it sounds, but also not as good as manger make it sound),



Most listeners can't detect 10% THD if the level of the distorted signal
is low compared to the non-distorted signal.


then you should try it.



I can't try Manger speakers since they are not distributed in North
America. Also, I can't afford them. I already made my choice, and it's a
horn based loudspeaker. Good enough compression drivers are cheap; the
magic (and the money) is in the horn.


which none of the above claims to do. home listeners are consumers.
there is no point in promoting something to consumers when (as you
point out) there is no product. you have to promote it to _producers_.



Right. But I'm a listener, not a consumer. I'm not a producer, but I
might become a non-professional one, when I'll have a working
ambisonics system at home.

Why is Ambisonics well known in the scientific community and not much
elsewhere? Why and how to promote Ambisonics to hobbyists and poor
students who don't have access to institutional labs and studios? Are
they a lost cause?

With Internet, we now can do things differently without the classic
producer/consumer mediation. If your target audience is only the
producers, Ambisonics will just be patented again and sold under new
names; it's just a matter of finding new tricks related to Ambisonics.
I know that's exactly what you're trying to avoid...

I will follow your tutorial to install my home system; without it, I'd
be lost. Your other tutorial (for producer) shows Ambisonics as a
spatialization tool for rendering stereo and 5.1 outputs; as a
"consumer" (I hate this word), why would I want to install a 10 speakers
periphonic system if producers just keep their amb files as masters?
There's a missing link...


If you could help me understand spherical harmonics, I'd be a "MAG
fanboy" in no time.



anyone who can grasp m/s stereo can grasp arbitrary order ambisonics.
i'm talking "understand the principle", not "grok all the
calculations and their implications to the nth degree".



I grasp it, but I don't understand it. After reading many articles, I'm
still lost, and I think it's important to understand part of the
maths. HOA sounds like a nice marketing acronym (it carries a
lot of mysticism and good vibes), but I can't just "believe"...


The best didactic resource I found is a very
strange article titled "Notes on Basic Ideas of Spherical
Harmonics". It's so good that I barely understand 10% of it.



isn't that a text by robert greene? i think i've read it. yeah, mr
greene is a mathematician, and they like it rigorous.



It's a fine text, but it reminded me how little math education I had.


but you don't need that level of understanding to use ambisonics. you
don't have to understand electronics to use an amplifier, and you
don't have to understand acoustics to use a microphone. some insight
helps, and the more you know the better, but being able to build some
piece of gear from scratch is not a prerequisite to get started.



True: there's no need to understand just to "use".
But it's always nice to know *why* to use!
There's no satisfaction in being just a "user" (or a consumer).


check out the link i posted earlier, it tries to introduce the
concept of spatial sampling to practical sound engineers. there's one
(intentional) gap in the logic, in that it starts with the
kirchhoff-helmholtz integral (which strictly speaking is the basis
for wfs, not ambisonics) and then jumps to spherical sampling. it's
not 100% kosher from

Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Jörn Nettingsmeier]

On 07/11/2011 12:39 AM, Stefan Schreiber wrote:


With all these efforts, why is actually nobody just marketing a
headphone solution with head-tracking?


smyth research makes one (called the realizer), or there's the 
beyerdynamic headzone.


--
Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487

Meister für Veranstaltungstechnik (Bühne/Studio)
Tonmeister VDT

http://stackingdwarves.net

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Marc Lavallée]

Jörn Nettingsmeier  a écrit :

> have you seen jerome daniel's "experimenter's corner"? 

I tried to read the beginning of his doctoral thesis; because it's in
French, I though it would be easier to understand than the vast
majority of papers in English, but I was wrong because the common
language of Ambisonics is... Mathematics! :-)

> besides being 
> _the_ HOA hotshot, he's a didactic genius. particularly his 
> illustrations are really helpful.
> 
> http://gyronymo.free.fr/audio3D/the_experimenter_corner.html

Indeed! 
His presentations are very good.
I will try his demonstrations.

I read that in 2009 he worked on the recording of Don Giovanni in HOA:
http://sites.radiofrance.fr/francemusique/ev/fiche.php?eve_id=245000165
Nine excerpts are available:
http://image.radio-france.fr/francemusique/_media/son/don-giovanni_multicanal.zip
These are 5.1 wav files. Too bad they're not AMB files.

--
Marc
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Bearcat M. Şandor]

On 07/10/2011 11:10 AM, Stefan Schreiber wrote:

> To clarify a few basic things:
> 
> The first poster in this thread (and obviously some other people who
> maybe should have known better) are claiming that you could receive a
> 360º representation via just two (supposedly narrow) front speakers.

First poster here. Just to clarify, i didn't claim anything like that. I
just asked if anyone had heard any of these recent 2-channel 3D audio
systems and wondered what they thought of them.  My main point was
whining about the expense of a 12+ channel audio system vs the
possibility of full sphere surround experience with 2 channels.  In
fact, i stated that i had not heard convincing 3D yet. Perhaps a more
forward sound stage, but i've heard good body from my speakers with no
"3D" applied.

-- 
Bearcat M. Şandor
Cell: 406.210.3500
Jabber/xmpp/gtalk/email: bear...@feline-soul.net
MSN: bearcatsan...@hotmail.com
Yahoo: bearcatsandor
AIM: bearcatmsandor


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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Marc Lavallée]

You can read the propaganda from Mangler 
about the "required" rise time of an amplifier:
http://www.manger-audio.co.uk/products.htm

Robert Greene  a écrit :

> No speaker requires a "fast" amplifier,
> whatever that means. ALL amplifiers that
> are not defective are far faster in any reasonable
> sense than any speaker is. Some amps
> have a tiny roll off of the extreme top
> on account of output networks or the like.
> But really this is a nonissue for any serious
> purposes.
> 
> Robert
> 
> On Sun, 10 Jul 2011, Marc Lavall?e wrote:
> 
> > J?rn Nettingsmeier  a ?crit :
> >
> >> On 07/10/2011 03:41 AM, Marc Lavall?e wrote:
> >>> I'm waiting for a pair of
> >>> very directional speakers that should (hopefully) help me enjoy
> >>> conventional stereo.
> >>
> >> then the manger might be for you:
> >> http://manger-msw.de/index.php?language=en
> >>
> >> this is a speaker that has been optimized for very good impulse
> >> response behaviour (at the expense of almost everything else).
> >
> > Then a fast amplifier is required.
> >
> >> in addition to its quick reaction, it's beaming like mad, which
> >> means that it practically eliminates early reflections over a wide
> >> band (a lot wider than conventional dome tweeters). its stereo
> >> reproduction is stunning.
> >
> > That's the idea: instead of adding tons of acoustic treatment in my
> > listening room, I prefer to invest in directive speakers.
> >
> >> if you can do with very little efficiency (sorry tube amp fans)
> >
> > The sensitivity of Manger speakers is about 88dB; that's not so bad.
> >
> >> and don't mind around 10% THD in the low frequencies (which is not
> >> as bad as it sounds, but also not as good as manger make it sound),
> >
> > Most listeners can't detect 10% THD if the level of the distorted
> > signal is low compared to the non-distorted signal.
> >
> >> then you should try it.
> >
> > I can't try Manger speakers since they are not distributed in North
> > America. Also, I can't afford them. I already made my choice, and
> > it's a horn based loudspeaker. Good enough compression drivers are
> > cheap; the magic (and the money) is in the horn.
> >
> >> which none of the above claims to do. home listeners are consumers.
> >> there is no point in promoting something to consumers when (as you
> >> point out) there is no product. you have to promote it to
> >> _producers_.
> >
> > Right. But I'm a listener, not a consumer. I'm not a producer, but I
> > might become a non-professional one, when I'll have a working
> > ambisonics system at home.
> >
> > Why is Ambisonics well known in the scientific community and not
> > much elsewhere? Why and how to promote Ambisonics to hobbyists and
> > poor students who don't have access to institutional labs and
> > studios? Are they a lost cause?
> >
> > With Internet, we now can do things differently without the classic
> > producer/consumer mediation. If your target audience is only the
> > producers, Ambisonics will just be patented again and sold under new
> > names; it's just a matter of finding new tricks related to
> > Ambisonics. I know that's exactly what you're trying to avoid...
> >
> > I will follow your tutorial to install my home system; without it,
> > I'd be lost. Your other tutorial (for producer) shows Ambisonics as
> > a spatialization tool for rendering stereo and 5.1 outputs; as a
> > "consumer" (I hate this word), why would I want to install a 10
> > speakers periphonic system if producers just keep their amb files
> > as masters? There's a missing link...
> >
> >>> If you could help me understand spherical harmonics, I'd be a "MAG
> >>> fanboy" in no time.
> >>
> >> anyone who can grasp m/s stereo can grasp arbitrary order
> >> ambisonics. i'm talking "understand the principle", not "grok all
> >> the calculations and their implications to the nth degree".
> >
> > I grasp it, but I don't understand it. After reading many articles,
> > I'm still lost, and I think it's important to understand part of the
> > maths. HOA sounds like a nice marketing acronym (it carries a
> > lot of mysticism and good vibes), but I can't just "believe"...
> >
> >>> The best didactic resource I found is a very
> >>> strange article titled "Notes on Basic Ideas of Spherical
> >>> Harmonics". It's so good that I barely understand 10% of it.
> >>
> >> isn't that a text by robert greene? i think i've read it. yeah, mr
> >> greene is a mathematician, and they like it rigorous.
> >
> > It's a fine text, but it reminded me how little math education I
> > had.
> >
> >> but you don't need that level of understanding to use ambisonics.
> >> you don't have to understand electronics to use an amplifier, and
> >> you don't have to understand acoustics to use a microphone. some
> >> insight helps, and the more you know the better, but being able to
> >> build some piece of gear from scratch is not a prerequisite to get
> >> started.
> >
> > True: there's no need to understand just to "use".
> > But it's always n

Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Robert Greene]

No speaker requires a "fast" amplifier,
whatever that means. ALL amplifiers that
are not defective are far faster in any reasonable
sense than any speaker is. Some amps
have a tiny roll off of the extreme top
on account of output networks or the like.
But really this is a nonissue for any serious
purposes.

Robert

On Sun, 10 Jul 2011, Marc Lavall?e wrote:


J?rn Nettingsmeier  a ?crit :


On 07/10/2011 03:41 AM, Marc Lavall?e wrote:

I'm waiting for a pair of
very directional speakers that should (hopefully) help me enjoy
conventional stereo.


then the manger might be for you:
http://manger-msw.de/index.php?language=en

this is a speaker that has been optimized for very good impulse
response behaviour (at the expense of almost everything else).


Then a fast amplifier is required.


in addition to its quick reaction, it's beaming like mad, which means
that it practically eliminates early reflections over a wide band (a
lot wider than conventional dome tweeters). its stereo reproduction
is stunning.


That's the idea: instead of adding tons of acoustic treatment in my
listening room, I prefer to invest in directive speakers.


if you can do with very little efficiency (sorry tube amp fans)


The sensitivity of Manger speakers is about 88dB; that's not so bad.


and don't mind around 10% THD in the low frequencies (which is not as
bad as it sounds, but also not as good as manger make it sound),


Most listeners can't detect 10% THD if the level of the distorted signal
is low compared to the non-distorted signal.


then you should try it.


I can't try Manger speakers since they are not distributed in North
America. Also, I can't afford them. I already made my choice, and it's a
horn based loudspeaker. Good enough compression drivers are cheap; the
magic (and the money) is in the horn.


which none of the above claims to do. home listeners are consumers.
there is no point in promoting something to consumers when (as you
point out) there is no product. you have to promote it to _producers_.


Right. But I'm a listener, not a consumer. I'm not a producer, but I
might become a non-professional one, when I'll have a working
ambisonics system at home.

Why is Ambisonics well known in the scientific community and not much
elsewhere? Why and how to promote Ambisonics to hobbyists and poor
students who don't have access to institutional labs and studios? Are
they a lost cause?

With Internet, we now can do things differently without the classic
producer/consumer mediation. If your target audience is only the
producers, Ambisonics will just be patented again and sold under new
names; it's just a matter of finding new tricks related to Ambisonics.
I know that's exactly what you're trying to avoid...

I will follow your tutorial to install my home system; without it, I'd
be lost. Your other tutorial (for producer) shows Ambisonics as a
spatialization tool for rendering stereo and 5.1 outputs; as a
"consumer" (I hate this word), why would I want to install a 10 speakers
periphonic system if producers just keep their amb files as masters?
There's a missing link...


If you could help me understand spherical harmonics, I'd be a "MAG
fanboy" in no time.


anyone who can grasp m/s stereo can grasp arbitrary order ambisonics.
i'm talking "understand the principle", not "grok all the
calculations and their implications to the nth degree".


I grasp it, but I don't understand it. After reading many articles, I'm
still lost, and I think it's important to understand part of the
maths. HOA sounds like a nice marketing acronym (it carries a
lot of mysticism and good vibes), but I can't just "believe"...


The best didactic resource I found is a very
strange article titled "Notes on Basic Ideas of Spherical
Harmonics". It's so good that I barely understand 10% of it.


isn't that a text by robert greene? i think i've read it. yeah, mr
greene is a mathematician, and they like it rigorous.


It's a fine text, but it reminded me how little math education I had.


but you don't need that level of understanding to use ambisonics. you
don't have to understand electronics to use an amplifier, and you
don't have to understand acoustics to use a microphone. some insight
helps, and the more you know the better, but being able to build some
piece of gear from scratch is not a prerequisite to get started.


True: there's no need to understand just to "use".
But it's always nice to know *why* to use!
There's no satisfaction in being just a "user" (or a consumer).


check out the link i posted earlier, it tries to introduce the
concept of spatial sampling to practical sound engineers. there's one
(intentional) gap in the logic, in that it starts with the
kirchhoff-helmholtz integral (which strictly speaking is the basis
for wfs, not ambisonics) and then jumps to spherical sampling. it's
not 100% kosher from a mathematical POV, but hopefully easier to
understand. and as the order goes up, the area of correct
reproduction expands, so that it ul

Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Marc Lavallée]

Stefan Schreiber  a écrit :

> Hello Marc...
> 
> I don't get access to the (dropbox) file.
> 
> >
> >   Error (404)
> >
> > We can't find the page you're looking for. 

It's not my DropBox, it's David's.
He probably removed the file. I get the same error.
His last message was :
"I have deleted my stuff as I am turning my back on audio 
for another decade after I tidy up some loose ends."
I hope he was not serious.

--
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Hello Marc...

I don't get access to the (dropbox) file.



  Error (404)

We can't find the page you're looking for. 




Is this because I am not based in the USA?

Best,

Stefan



Marc Lavallée wrote:


dw  a écrit :

 


On 10/07/2011 18:10, Stefan Schreiber wrote:
   

If you can't reproduce full horizontal 360º surround via two front 
speakers, then the "binaural via two loudspeakers" approach doesn't 
work, and there is no solution to reproduce "3D sound" in this way. 
(Your colleague Choueiri claims this on the cited web page, and

with every respect, no way...)
 


It can work but is not robust. Get a Jambox and don't move your head
in this case.
http://dl.dropbox.com/u/20268768/auberge-clip.wav - He walks in front 
and returns behind for most people.
   



What so special with the Jambox? I tried with small speakers. The stage
is no larger than 120 degrees. When the walker comes back; he was
probably walking behind, but to me the sound is just louder and there's
less echo, as if we was nearer, not really behind. But it's a nice clip!
--
Marc
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Ralph Glasgal wrote:


Thanks Stefan.  The very bottom remarks are really about previous posts.

In theory it is possible to do full periphonic sound via two somethings (maybe 
not looudspeakers as we know them).  Choueiri believes he can come close to 
this by using laser-like loudspeakers, precision placed in a quiet room, with a 
single listener in a known position in the near field.



So, this is about avoiding the artefacts which I was "postulating". 
Obviously this is the hard part...


(I have already answered to RG that I believe that you can simulate 
headphones via two speakers, but only in theory. If I am would be proven 
wrong, I actually would be quite happy about this!   :-) )


It might be possible to track the position of a listener via a camera, 
Kinect style... (As long as we speak about a first lab implementation in 
Princeton, which could be simplified later.)


Actually, some 3D video solutions without glasses will track the 
position of an observer. Similar problem...



 With ILDs up to 20 dB or more and full ITDs up to 700 microseconds much is 
possible frontally without resort to HRTF trickery and one can get both width 
and depth and some sense toward the rear with special recordings.   To get the 
full rear part of the soundfield and height, he needs to make recordings using 
a dummy head mic with pinna and add some HRTF functions.  This extreme method 
does work and you can go to Princeton and hear it for yourself.

Of course, nothing is perfect and since the speakers are frontal there are some 
pinna direction finding errors and listening with the pinna of a dummy head on 
top of your own is not for everyone.  If you use your own head as the recording 
microphone his methodolgy is likely as good as it needs to be.  Maybe Edgar 
Choueiri will do an impulse response of your pinna and correct even for this 
double pinna error.
 

With all these efforts, why is actually nobody just marketing a 
headphone solution with head-tracking?


I mean, this is vey possible nowadays, really nothing special. You need 
gyroscopes and a sound processor, which might be based on a small SoC 
design based on an ARM processor. (Doesn't need a lot of power.)




There is no simple way earphones can be used to achieve this level of binaural psychoacoustic verisimilitude because of pinna problems. 
 



Maybe the pinna problems are just overrated, but I could be wrong on this.
In any case, you could measure your own HRTF response, and it is not so 
difficult as it sounds.


Thanks for the hint that there is actually a double pinna error. Many 
people think there is just one, which is too simple...


(You only have to get into the pinna issues in Ambiophonics if you start 
using binaural recordings. Just for clarification...)



But if you make a recording with microphones in your own ear canal and them 
play them back with etymotic ear buds, you can get close except for the head 
motion problem where the stage swings around as you move your head.

...





Even for pop music where the ILD and ITD have been pairwisepanned to sonic 
oblivion, or were electronic to start with, it is tough to make the case that
limiting reproduced ITD to about 200 microseconds and ILD to maybe 5 due to stereo crosstalk is a good idea no matter how the recording engineer decided to mix the recording based on what he heard using his monitor angle and his head size.  His monitoring comb filtering pattern will not be anything like what you  have, etc.  There is also the bass boost issue for central soloists or instruments that XTC can eliminate or not as you wish.  But in the pop world, it is the Jambox/Foxl Ambiophonic app generation where the action will be and I presume recording engineers will take that market into account and master accordingly.  It is easy to make mixes that are both stereo and Ambio compatible. 
 

Probably recording engineers mixing for pop music will already test for 
headphones, which was my point.




But nearly all the RACE implementations include controls to compensate for 
recordings where you may not want complete XTC.  They also have bypass controls 
so you can do an instant comparison between stereo and Ambio.
 



Very reasonable.


Best regards,

Stefan Schreiber

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Ralph Glasgal]

Thanks Stefan.  The very bottom remarks are really about previous posts.
 
In theory it is possible to do full periphonic sound via two somethings (maybe 
not looudspeakers as we know them).  Choueiri believes he can come close to 
this by using laser-like loudspeakers, precision placed in a quiet room, with a 
single listener in a known position in the near field.  With ILDs up to 20 dB 
or more and full ITDs up to 700 microseconds much is possible frontally without 
resort to HRTF trickery and one can get both width and depth and some sense 
toward the rear with special recordings.   To get the full rear part of the 
soundfield and height, he needs to make recordings using a dummy head mic with 
pinna and add some HRTF functions.  This extreme method does work and you can 
go to Princeton and hear it for yourself.

Of course, nothing is perfect and since the speakers are frontal there are some 
pinna direction finding errors and listening with the pinna of a dummy head on 
top of your own is not for everyone.  If you use your own head as the recording 
microphone his methodolgy is likely as good as it needs to be.  Maybe Edgar 
Choueiri will do an impulse response of your pinna and correct even for this 
double pinna error.
 
There is no simple way earphones can be used to achieve this level of binaural 
psychoacoustic verisimilitude because of pinna problems.  But if you make a 
recording with microphones in your own ear canal and them play them back with 
etymotic ear buds, you can get close except for the head motion problem where 
the stage swings around as you move your head.
 
Yes in a full Ambiophonic system we like to use four speakers even for 2.0 
media.  Also for classical music it is nice to convolve concert hall impulse 
responses to feed surround speakers.   Out of thousands of CDs and LPs I have 
played here in the last five years only one or two could be said to sound 
better in stereo than Ambio.  So I don't quite know what Fons is on about.  I 
can't speak for the pop world, but when it comes to movies I can say the same 
thing.  Compared to 5.1 Ambio works better for TV and DVDs than 5.1 or simple 
stereo.  You should hear Avatar via four speaker 4.0 Ambiophonics.
 
The only problem I have with opera DVDs or BDs of which I now have hundreds is 
that half of them have monophonic solo vocal tracks.  So a singer off to the 
right sounds from the middle.  I have raised this issue with the IRT but 
nothing will happen.  The recent Blueray Ring Cycle has a full width orchestral 
stage and some solo localization and is a sonic blockbuster.  The older laser 
disk opera recordings all have really splendid localization cues and are 
exciting to hear.
 
Even for pop music where the ILD and ITD have been pairwisepanned to sonic 
oblivion, or were electronic to start with, it is tough to make the case that
limiting reproduced ITD to about 200 microseconds and ILD to maybe 5 due to 
stereo crosstalk is a good idea no matter how the recording engineer decided to 
mix the recording based on what he heard using his monitor angle and his head 
size.  His monitoring comb filtering pattern will not be anything like what 
you  have, etc.  There is also the bass boost issue for central soloists or 
instruments that XTC can eliminate or not as you wish.  But in the pop world, 
it is the Jambox/Foxl Ambiophonic app generation where the action will be and I 
presume recording engineers will take that market into account and master 
accordingly.  It is easy to make mixes that are both stereo and Ambio 
compatible. 
 
But nearly all the RACE implementations include controls to compensate for 
recordings where you may not want complete XTC.  They also have bypass controls 
so you can do an instant comparison between stereo and Ambio.
 
Ralph Glasgal
www.ambiophonics.org

From: Stefan Schreiber 
The first poster in this thread (and obviously some other people who maybe 
should have known better) are claiming that you could receive a 360º 
representation via just two (supposedly narrow) front speakers.

This is probably not feasible, at least nobody can demonstrate anything which 
works like this - in practice. It is also nothing that Ambiophonics aims at. 
(You are obviously using two speaker pairs-  i.e. four speakers - for 360º 
surround sound, whereas narrow front speakers are for wide stereo 
representation.)

If you can't reproduce full horizontal 360º surround via two front speakers, 
then the "binaural via two loudspeakers" approach doesn't work, and there is no 
solution to reproduce "3D sound" in this way. (Your colleague Choueiri claims 
this on the cited web page, and with every respect, no way...)

My (negative) review of Choueiri's demonstrations ;-)  was/is not aimed at 
Ambiophonics at all, because there are differences, and you don't claim 
anything which is either impossible or near-impossible.

(Ambiophonics includes XTC, or "uses" XTC. )

Best regards,

Stefan
-- next part --

Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Jörn Nettingsmeier]

On 07/10/2011 06:14 PM, Marc Lavallée wrote:

Jörn Nettingsmeier  a écrit :

and don't mind around 10% THD in the low frequencies (which is not as
bad as it sounds, but also not as good as manger make it sound),


oops, this is bogus. THD means "total harmonic distortion", so it makes 
no sense to talk about band-limited THD. what i meant is: the distortion 
level is 10% at the lower end of the spectrum covered by the manger 
driver...



Why is Ambisonics well known in the scientific community and not much
elsewhere? Why and how to promote Ambisonics to hobbyists and poor
students who don't have access to institutional labs and studios? Are
they a lost cause?


no. the initial cost of an ambisonic system is low: four speakers and a 
computer. since most ambisonic knowledge is shared openly and there is 
some great free software, the basic hurdle is actually quite low.
the demise of ambisonia.com is lamentable, but there is quite some 
first-order material in circulation that's free for private listening.


i have been really bad at getting more free stuff out there, but 
securing all those rights is such a f..ing nightmare :(
but i promise to dig into my recordings some day and share all that can 
be legally shared under reasonable terms (i.e. some cc type of license).



With Internet, we now can do things differently without the classic
producer/consumer mediation. If your target audience is only the
producers, Ambisonics will just be patented again and sold under new
names; it's just a matter of finding new tricks related to Ambisonics.
I know that's exactly what you're trying to avoid...


it happens all the time. but there are numerous people willing and able 
to call BS when that happens. spatial snakeoil is abundant, and it 
creates confusion for people who want to explore surround, but it's not 
really a threat to a free spatial sound community.



Your other tutorial (for producer) shows Ambisonics as a
spatialization tool for rendering stereo and 5.1 outputs; as a
"consumer" (I hate this word),


if you're willing to tinker and maybe even record your own stuff, you're 
a creator. i share your dislike of the term, it was just used because 
many people explicitly do not want to (have to) tinker but be able to 
buy a product.



why would I want to install a 10 speakers
periphonic system if producers just keep their amb files as masters?
There's a missing link...


well, in my shiny version of the future, those ambi masters would of 
course be made available to ambisonic enthusiasts today, even if it's 
just a very small market. once the spatial tide has turned and all the 
joe sixpacks out there have ambisonic car radios, labels with large HOA 
back catalogues will make a mint in the reissue business.


even if that's not going to happen, mastering in ambisonics is a big 
advantage if stereo is surpassed by 5.1 is surpassed by 7.1 is surpassed 
by 22.2 is, because you just re-render. while you're at it, why not 
throw together a limited edition collector's box with b-format files on 
an extra dvd?



I grasp it, but I don't understand it. After reading many articles, I'm
still lost, and I think it's important to understand part of the
maths. HOA sounds like a nice marketing acronym (it carries a
lot of mysticism and good vibes),


oh my... :)


but I can't just "believe"...


phew!


The best didactic resource I found is a very
strange article titled "Notes on Basic Ideas of Spherical
Harmonics". It's so good that I barely understand 10% of it.


isn't that a text by robert greene? i think i've read it. yeah, mr
greene is a mathematician, and they like it rigorous.


It's a fine text, but it reminded me how little math education I had.


oh how i share your grief :)


There's no satisfaction in being just a "user" (or a consumer).


with that mindset, ambisonics could be a great hobby!


I already read your aticles, they are really good to intuitively
understand Ambisonics. I'll read them again and again, then try
to review my old maths and learn new ones.


check out the proceedings of the ambisonics symposia (graz 2009, paris 
2010, lexington 2011), there are some papers that are not too hard to 
understand... the way i do it is iterate: read a paper, get lost, read 
another, grok another aspect, and at some point revisit the first paper, 
grok a few more aspects, and so on :)


have you seen jerome daniel's "experimenter's corner"? besides being 
_the_ HOA hotshot, he's a didactic genius. particularly his 
illustrations are really helpful.


http://gyronymo.free.fr/audio3D/the_experimenter_corner.html


best,

jörn



--
Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487

Meister für Veranstaltungstechnik (Bühne/Studio)
Tonmeister VDT

http://stackingdwarves.net

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[dw]

This one is vaguely in-head rather than down, and also well-out-of head. 
I am doing these with the my public domain 'stereo' filter, which is not 
ideal for this. I have deleted my stuff as I am turning my back on audio 
for another decade after I tidy up some loose ends.

http://dl.dropbox.com/u/20268768/sg.wav
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[dw]

On 10/07/2011 19:36, Marc Lavallée wrote:

dw  a écrit :


On 10/07/2011 18:10, Stefan Schreiber wrote:


If you can't reproduce full horizontal 360º surround via two front
speakers, then the "binaural via two loudspeakers" approach doesn't
work, and there is no solution to reproduce "3D sound" in this way.
(Your colleague Choueiri claims this on the cited web page, and
with every respect, no way...)

It can work but is not robust. Get a Jambox and don't move your head
in this case.
http://dl.dropbox.com/u/20268768/auberge-clip.wav - He walks in front
and returns behind for most people.

What so special with the Jambox?


It is one thing that E Choueiri uses for demos, I know it works. It must 
be used very near-field. I don't have an anechoic chamber and that is 
the next best thing.

  I tried with small speakers. The stage
is no larger than 120 degrees. When the walker comes back; he was
probably walking behind, but to me the sound is just louder and there's
less echo, as if we was nearer, not really behind. But it's a nice clip!
--
Marc
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Marc Lavallée]

dw  a écrit :

> On 10/07/2011 18:10, Stefan Schreiber wrote:
> >
> >
> > If you can't reproduce full horizontal 360º surround via two front 
> > speakers, then the "binaural via two loudspeakers" approach doesn't 
> > work, and there is no solution to reproduce "3D sound" in this way. 
> > (Your colleague Choueiri claims this on the cited web page, and
> > with every respect, no way...)
> 
> It can work but is not robust. Get a Jambox and don't move your head
> in this case.
> http://dl.dropbox.com/u/20268768/auberge-clip.wav - He walks in front 
> and returns behind for most people.

What so special with the Jambox? I tried with small speakers. The stage
is no larger than 120 degrees. When the walker comes back; he was
probably walking behind, but to me the sound is just louder and there's
less echo, as if we was nearer, not really behind. But it's a nice clip!
--
Marc
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[dw]

On 10/07/2011 18:10, Stefan Schreiber wrote:



If you can't reproduce full horizontal 360º surround via two front 
speakers, then the "binaural via two loudspeakers" approach doesn't 
work, and there is no solution to reproduce "3D sound" in this way. 
(Your colleague Choueiri claims this on the cited web page, and with 
every respect, no way...)


It can work but is not robust. Get a Jambox and don't move your head in 
this case.
http://dl.dropbox.com/u/20268768/auberge-clip.wav - He walks in front 
and returns behind for most people.


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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Marc Lavallée wrote:


Stefan Schreiber  a écrit :

 


Now come on, a square wave is not about music!
   



Iannis Xenakis would not agree with you...

--
Marc
___
 



But HIS square waves are irregular, or a chain of singularities.   :-)


Best,

Stefan
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Marc Lavallée]

Stefan Schreiber  a écrit :

> Now come on, a square wave is not about music!

Iannis Xenakis would not agree with you...

--
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Fons Adriaensen wrote:


On Sun, Jul 10, 2011 at 05:44:50PM +0100, Stefan Schreiber wrote:

 

As a violinist, my choice would be the sawtooth wave, just for  
demonstrational purposes.
   



Which has the same problems (infinite bandwidth etc.)
But yes, as a violinist it would probably hurt your
ears less...

Ciao,

 

Disagree, because a sawtooth wave is a natural musical wave 
(obviously!), and you can reproduce it sufficiently well, even with 44.1kHz.


Could you just admit once that you are not right?!

Now come on, a square wave is not about music!

Best,

Stefan Schreiber


P.S.: It is about electronics. Full stop.
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Ralph Glasgal wrote:


Although I have done this many times before, I again put on a left right test 
track using RACE and two line source ESL speakers and I can rotate my head as 
much as my neck permits without detecting any noticeable shift in the 
localization of the voices at the extreme right and left.  With two speakers if 
I stand up so I can rotate even more then the localization begins to shift but 
not all that much.  But with both front and rear speakers engaged even this 
does not happen.  Compared to earphone listening, the stage stays put with 
normal head rotation using this loudspeaker binaural method and head tracking 
is not required.

In the concert hall or movie theater one does not rotate the head all that much 
so I fail to see the significance of a possible 2nd degree fault of XTC here.
 



Thanks for the remarks!

To clarify a few basic things:

The first poster in this thread (and obviously some other people who 
maybe should have known better) are claiming that you could receive a 
360º representation via just two (supposedly narrow) front speakers.


This is probably not feasible, at least nobody can demonstrate anything 
which works like this - in practice. It is also nothing that 
Ambiophonics aims at. (You are obviously using two speaker pairs-  i.e. 
four speakers - for 360º surround sound, whereas narrow front speakers 
are for wide stereo representation.)


If you can't reproduce full horizontal 360º surround via two front 
speakers, then the "binaural via two loudspeakers" approach doesn't 
work, and there is no solution to reproduce "3D sound" in this way. 
(Your colleague Choueiri claims this on the cited web page, and with 
every respect, no way...)


My (negative) review of Choueiri's demonstrations ;-)  was/is not aimed 
at Ambiophonics at all, because there are differences, and you don't 
claim anything which is either impossible or near-impossible.


(Ambiophonics includes XTC, or "uses" XTC. )


Best regards,

Stefan

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Marc Lavallée]

Stefan Schreiber  a écrit :

> I don't want to annoy anybody or you, but don't explain acoustics via 
> square waves...

I think that square waves is a good choice because of the amount of
resolution required, and because of their harmonic distribution:
http://www.youtube.com/watch?v=y6crWlxKB_E
http://www.youtube.com/watch?v=AjlHBx0zV7c

--
Marc
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Fons Adriaensen]

On Sun, Jul 10, 2011 at 05:44:50PM +0100, Stefan Schreiber wrote:

> As a violinist, my choice would be the sawtooth wave, just for  
> demonstrational purposes.

Which has the same problems (infinite bandwidth etc.)
But yes, as a violinist it would probably hurt your
ears less...

Ciao,

-- 
FA

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Fons Adriaensen wrote:


On Sat, Jul 09, 2011 at 09:41:04PM -0400, Marc Lavallée wrote:

 


If you could help me understand spherical harmonics, I'd be a "MAG
fanboy" in no time. The best didactic resource I found is a very
strange article titled "Notes on Basic Ideas of Spherical Harmonics".
It's so good that I barely understand 10% of it.
   



What you probably need is some intuitive understanding of them.
I've tried it many times, and the following seems to work well
with most people interested in the subject.

You are probably familiar with the fact that a cyclic waveform,
e.g. a square wave, corresponds to an harmonic line spectrum:
if the fundamental frequency is F, the waveform is the sum of
a number of sine/cosine waves with frequencies k * F, with k
an integer.
 



The square wave is exactly the oddest example for musical or acoustical 
purposes which I could imagine!!


Firstly, there are serious problems to sample this. (You would need very 
high sample frequencies, and just to receive some form of approximation.)
Secondly, any amplifier or any loudspeaker would have "seious" problems 
to reproduce this. Thirdly, I don't know how a square wave sounds...
:-)  (ok, this was a  joke...)


As a violinist, my choice would be the sawtooth wave, just for 
demonstrational purposes.


Now some cite from the little accurate Wikipedia:

http://en.wikipedia.org/wiki/Square_wave

A square wave is a kind of non-sinusoidal waveform 
, most typically 
encountered in electronics  
and signal processing 
. An ideal square wave 
alternates regularly and instantaneously between two levels. Its 
stochastic counterpart is a two-state trajectory 
.



And this is not about acoustics, unless you talk about synthesizers.

The rest you wrote is probably right, although I didn't have time to 
reflect about this.   ;-)


I don't want to annoy anybody or you, but don't explain acoustics via 
square waves...



Best,

Stefan

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Ralph Glasgal]

Although I have done this many times before, I again put on a left right test 
track using RACE and two line source ESL speakers and I can rotate my head as 
much as my neck permits without detecting any noticeable shift in the 
localization of the voices at the extreme right and left.  With two speakers if 
I stand up so I can rotate even more then the localization begins to shift but 
not all that much.  But with both front and rear speakers engaged even this 
does not happen.  Compared to earphone listening, the stage stays put with 
normal head rotation using this loudspeaker binaural method and head tracking 
is not required.
 
In the concert hall or movie theater one does not rotate the head all that much 
so I fail to see the significance of a possible 2nd degree fault of XTC here.
 
The question now is why is RACE XTC so robust that this rotation effect is 
not clearly evident especially with four (curved in this case) speakers.  The 
answer has to be that the signal is the same at both ears despite appearances 
or that despite the differences present the brain still localizes normally.
 
Ralph Glasgal
www.ambiophonics.org    

From: Fons Adriaensen 
Imagine a XTC system reproducing someone speaking at say 60
degrees left. If I turn my head towards the virtual speaker
I expect more or less the same signal in both ears. There's
no way to achieve that with one ear almost facing the speakers
and the other one turned away from them.

Ciao,

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Marc Lavallée]

Robert Greene  a écrit :

> Is this the one you mean(the "strange article")?
> 
> http://www.regonaudio.com/SphericalHarmonics.pdf

Yes! :)

> I wrote it myself!
> I surely did not mean for it to be strange at all.
> But the idea is intrinsically a bit complicated.
> What one is really doing is developing ad hoc
> eigenfunctions of the Laplacian on the sphere.
> This is not going to be really easy no matter
> how you do it, not if you really do it anyway.
> 
> But the idea is in outline fairly simple. One
> is just trying to find some polynomials that
> when you restrict them to the sphere
> give you a way to approximate general functions
> on the sphere in a systematic way.

The maths are strange, not the ideas.

> I hope the article helps. I did the best I could!

I does help a lot. The Wikipedia article too:
http://en.wikipedia.org/wiki/Spherical_harmonics

But I'd need to go back to school to understand the maths...
I'll get it, one day...

Thanks!
--
Marc
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Marc Lavallée]

Jörn Nettingsmeier  a écrit :

> On 07/10/2011 03:41 AM, Marc Lavallée wrote:
> > I'm waiting for a pair of
> > very directional speakers that should (hopefully) help me enjoy
> > conventional stereo.
> 
> then the manger might be for you:
> http://manger-msw.de/index.php?language=en
> 
> this is a speaker that has been optimized for very good impulse
> response behaviour (at the expense of almost everything else).

Then a fast amplifier is required.

> in addition to its quick reaction, it's beaming like mad, which means 
> that it practically eliminates early reflections over a wide band (a
> lot wider than conventional dome tweeters). its stereo reproduction
> is stunning.

That's the idea: instead of adding tons of acoustic treatment in my
listening room, I prefer to invest in directive speakers. 

> if you can do with very little efficiency (sorry tube amp fans) 

The sensitivity of Manger speakers is about 88dB; that's not so bad. 

> and don't mind around 10% THD in the low frequencies (which is not as
> bad as it sounds, but also not as good as manger make it sound), 

Most listeners can't detect 10% THD if the level of the distorted signal
is low compared to the non-distorted signal.

> then you should try it.

I can't try Manger speakers since they are not distributed in North
America. Also, I can't afford them. I already made my choice, and it's a
horn based loudspeaker. Good enough compression drivers are cheap; the
magic (and the money) is in the horn.

> which none of the above claims to do. home listeners are consumers. 
> there is no point in promoting something to consumers when (as you
> point out) there is no product. you have to promote it to _producers_.

Right. But I'm a listener, not a consumer. I'm not a producer, but I
might become a non-professional one, when I'll have a working
ambisonics system at home. 

Why is Ambisonics well known in the scientific community and not much
elsewhere? Why and how to promote Ambisonics to hobbyists and poor
students who don't have access to institutional labs and studios? Are
they a lost cause? 

With Internet, we now can do things differently without the classic
producer/consumer mediation. If your target audience is only the
producers, Ambisonics will just be patented again and sold under new
names; it's just a matter of finding new tricks related to Ambisonics.
I know that's exactly what you're trying to avoid...

I will follow your tutorial to install my home system; without it, I'd
be lost. Your other tutorial (for producer) shows Ambisonics as a
spatialization tool for rendering stereo and 5.1 outputs; as a
"consumer" (I hate this word), why would I want to install a 10 speakers
periphonic system if producers just keep their amb files as masters?
There's a missing link...

> > If you could help me understand spherical harmonics, I'd be a "MAG
> > fanboy" in no time.
> 
> anyone who can grasp m/s stereo can grasp arbitrary order ambisonics.
> i'm talking "understand the principle", not "grok all the
> calculations and their implications to the nth degree".

I grasp it, but I don't understand it. After reading many articles, I'm
still lost, and I think it's important to understand part of the
maths. HOA sounds like a nice marketing acronym (it carries a
lot of mysticism and good vibes), but I can't just "believe"...

> > The best didactic resource I found is a very
> > strange article titled "Notes on Basic Ideas of Spherical
> > Harmonics". It's so good that I barely understand 10% of it.
> 
> isn't that a text by robert greene? i think i've read it. yeah, mr 
> greene is a mathematician, and they like it rigorous. 

It's a fine text, but it reminded me how little math education I had.

> but you don't need that level of understanding to use ambisonics. you
> don't have to understand electronics to use an amplifier, and you
> don't have to understand acoustics to use a microphone. some insight
> helps, and the more you know the better, but being able to build some
> piece of gear from scratch is not a prerequisite to get started.

True: there's no need to understand just to "use".
But it's always nice to know *why* to use!
There's no satisfaction in being just a "user" (or a consumer).

> check out the link i posted earlier, it tries to introduce the
> concept of spatial sampling to practical sound engineers. there's one 
> (intentional) gap in the logic, in that it starts with the 
> kirchhoff-helmholtz integral (which strictly speaking is the basis
> for wfs, not ambisonics) and then jumps to spherical sampling. it's
> not 100% kosher from a mathematical POV, but hopefully easier to
> understand. and as the order goes up, the area of correct
> reproduction expands, so that it ultimately approaches the KH surface
> from the inside. if you're in a hurry, there are slides as well,
> which are a lot more compact: 
> http://stackingdwarves.net/public_stuff/linux_audio/tmt10/TMT2010_J%c3%b6rn_Nettingsmeier-Higher_order_Ambisonics-Slides.pdf

I a

Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Robert Greene]

Is this the one you mean(the "strange article")?


http://www.regonaudio.com/SphericalHarmonics.pdf

I wrote it myself!
I surely did not mean for it to be strange at all.
But the idea is intrinsically a bit complicated.
What one is really doing is developing ad hoc
eigenfunctions of the Laplacian on the sphere.
This is not going to be really easy no matter
how you do it, not if you really do it anyway.

But the idea is in outline fairly simple. One
is just trying to find some polynomials that
when you restrict them to the sphere
give you a way to approximate general functions
on the sphere in a systematic way.

I hope the article helps. I did the best I could!

Robert
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Fons Adriaensen]

On Sun, Jul 10, 2011 at 11:49:49AM +0100, dw wrote:

> You snipped the context.
>
> "i don't think that's possible. imagine two similar instruments, one at  
> 0° and the other at 180°. once recorded in mono, they will be fused  
> together irrevocably. you won't be able to separate them with the help  
> of any vector metadata."

No I did not snip the context. I responded to this: (the lines
just above mine)

>>> Any microphone capable of separating two sound sources MUST be large in
>>> terms of wavelengths (similar to the diffraction limit for  telescopes)
>>> The soundfield microphone cannot  separate two or more sound sources at
>>> _any_  frequency for this reason.

This assertion does not refer at all to what you claim to
be the context, or depend on it, and it is wrong.

> What is not true? I thought the whole point of higher orders was higher  
> resolution so that you could make less efficient use of your speakers..

In that you are clearly mistaken. 

Ciao,

-- 
FA

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[dw]

On 10/07/2011 11:02, Fons Adriaensen wrote:

On Sun, Jul 10, 2011 at 10:10:49AM +0100, dw wrote:


Any microphone capable of separating two sound sources MUST be large in
terms of wavelengths (similar to the diffraction limit for  telescopes)
The soundfield microphone cannot  separate two or more sound sources at
_any_  frequency for this reason.

First this is not true, second it is irrelevant. You don't need to
'separate' sources (i.e. procude signals that each contain one source)
in order to reproduce them.

You snipped the context.

"i don't think that's possible. imagine two similar instruments, one at 
0° and the other at 180°. once recorded in mono, they will be fused 
together irrevocably. you won't be able to separate them with the help 
of any vector metadata."


What is not true? I thought the whole point of higher orders was higher 
resolution so that you could make less efficient use of your speakers..

This does not seem to worry the 'fanboys'.

Indeed it does not.

The problem with higher order mics at LF is of a different nature:
they require very high gains on difference signals if the mic is
small compared to wavelength.

OTOH, high order at low F is not essential for reproduction.
You can produce 3rd order AMB with the Eigenmike. But the
problem is that the frequency range gets limited at both
ends as order goes up. A normal AMB decoder expects full
range signals at all orders, so it will produce a poor
result. It is possible to create a decoder adapted to the
available frequency ranges, i.e. one that changes order in
function of frequency and would be full high order only for
medium frequencies. Problem with this is that there is no
standard way - the decoder depends on the mic.

Ciao,



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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Fons Adriaensen]

On Sun, Jul 10, 2011 at 10:10:49AM +0100, dw wrote:

> Any microphone capable of separating two sound sources MUST be large in  
> terms of wavelengths (similar to the diffraction limit for  telescopes)
> The soundfield microphone cannot  separate two or more sound sources at
> _any_  frequency for this reason.

First this is not true, second it is irrelevant. You don't need to 
'separate' sources (i.e. procude signals that each contain one source)
in order to reproduce them.

> This does not seem to worry the 'fanboys'.

Indeed it does not.

The problem with higher order mics at LF is of a different nature:
they require very high gains on difference signals if the mic is
small compared to wavelength.

OTOH, high order at low F is not essential for reproduction.
You can produce 3rd order AMB with the Eigenmike. But the
problem is that the frequency range gets limited at both
ends as order goes up. A normal AMB decoder expects full
range signals at all orders, so it will produce a poor 
result. It is possible to create a decoder adapted to the
available frequency ranges, i.e. one that changes order in
function of frequency and would be full high order only for
medium frequencies. Problem with this is that there is no
standard way - the decoder depends on the mic.

Ciao,

-- 
FA

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[dw]

On 10/07/2011 09:00, Jörn Nettingsmeier wrote:

On 07/10/2011 12:32 AM, dw wrote:

I was thinking more of recording in mono, computing the vectors in
various bands from the output of some large microphone array and then
encoding (the mono sound) into the required number of spherical
harmonics.


i don't think that's possible. imagine two similar instruments, one at 
0° and the other at 180°. once recorded in mono, they will be fused 
together irrevocably. you won't be able to separate them with the help 
of any vector metadata.


Any microphone capable of separating two sound sources MUST be large in 
terms of wavelengths (similar to the diffraction limit for  telescopes)

The soundfield microphone cannot  separate two or more sound sources at
_any_  frequency for this reason. This does not seem to worry the 'fanboys'.


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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Fons Adriaensen]

On Sat, Jul 09, 2011 at 09:41:04PM -0400, Marc Lavallée wrote:
 
> If you could help me understand spherical harmonics, I'd be a "MAG
> fanboy" in no time. The best didactic resource I found is a very
> strange article titled "Notes on Basic Ideas of Spherical Harmonics".
> It's so good that I barely understand 10% of it.

What you probably need is some intuitive understanding of them.
I've tried it many times, and the following seems to work well
with most people interested in the subject.

You are probably familiar with the fact that a cyclic waveform,
e.g. a square wave, corresponds to an harmonic line spectrum:
if the fundamental frequency is F, the waveform is the sum of
a number of sine/cosine waves with frequencies k * F, with k
an integer.

The thing that connects the two representations, the waveform
as a function of time and the spectrum, is the Fourier trans-
form or its inverse. We can switch between the two at any time
without loss of information, both one cycle of the waveform and
its spectrum contain all there is to know about the waveform.

Visualise the waveform as a function of time, with time on
the x-axis, and cut out a piece corresponding to one cycle.
We can bend this piece of x-axis into a circle. Now instead
if interpreting that axis (now a circle) as 'time' we can
interpret it as an angle: every point on the circle corres-
ponds to a direction (as seen from the center).

So anything that is a function of e.g. direction in the
horizontal plane can be represented by a 'spectrum' as
well.

Can we generalise this to directions not just in the H plane
but in 3-D space ? Let's try using a 2-D Fourier transform,
just as we used a 1-D FT for 2-D space (a plane).

The equivalent of a cyclic function in that case is plane
consisting of identical square tiles - it is cyclic both in
x and y, and the 2-D Fourier transform can be used to compute
its spectrum (a very common thing e.g. in image processing).

We can cut out one square, just as we did with the single
period before, and try to bend it into a sphere since
directions in 3-D space correspond to points on a sphere.

We can take the top and bottom edges and bring them together,
forming a tube. Now we can bend the tube to bring its two
ends together. In both cases the points that meet have the
same function value, so we preserve the cyclic nature of
our function. 

But the result is not sphere as we would want, but a torus.

Can we bend somehow our square into a sphere and such that
identical points on the edges are brought together ? The
answer is no, it can't be done. For both a torus and a
sphere we can identify any point on it with two coordinates,
e.g. azimuth and elevation, but they are fundamentally 
different surfaces. On a torus the two coordinates are
really independent, on a sphere they are not. 

So we no know that a 2-D Fourier transform can't be used
to find the spectrum of a function defined on the sphere,
as we could do using the 1-D FT on a circle.

Then _what_ does correspond to the components of a spectrum
on a sphere ? This turns out to be the set of functions 
called Spherical Harmonics. They arise quite naturally when
trying to solve some equations (e.g. the wave equation) in
3-D space using spherical coordinates instead of x,y,z,
just as sine and cosine appear as the solutions of similar
but simpler equations.

Ciao,

-- 
FA

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Jörn Nettingsmeier]

On 07/10/2011 03:41 AM, Marc Lavallée wrote:

I'm waiting for a pair of
very directional speakers that should (hopefully) help me enjoy
conventional stereo.


then the manger might be for you: http://manger-msw.de/index.php?language=en

this is a speaker that has been optimized for very good impulse response 
behaviour (at the expense of almost everything else).
in addition to its quick reaction, it's beaming like mad, which means 
that it practically eliminates early reflections over a wide band (a lot 
wider than conventional dome tweeters). its stereo reproduction is stunning.


if you can do with very little efficiency (sorry tube amp fans) and 
don't mind around 10% THD in the low frequencies (which is not as bad as 
it sounds, but also not as good as manger make it sound), then you 
should try it.



Presenting ambisonics as a scientific tool,


which it is


a sound engineering secret,


which it hopefully isn't anymore, at least many people are working hard 
to make it widely known as a viable alternative



or a surround system for museums


which is a very interesting usecase


or stadiums,


which it is absolutely not, and nobody in their right minds is doing that


are not very good ways to
promote it to home listeners,

> especially considering the quasi-absence
> of ambisonics material in circulation.

which none of the above claims to do. home listeners are consumers. 
there is no point in promoting something to consumers when (as you point 
out) there is no product. you have to promote it to _producers_.



If you could help me understand spherical harmonics, I'd be a "MAG
fanboy" in no time.


anyone who can grasp m/s stereo can grasp arbitrary order ambisonics.
i'm talking "understand the principle", not "grok all the calculations 
and their implications to the nth degree".



The best didactic resource I found is a very
strange article titled "Notes on Basic Ideas of Spherical Harmonics".
It's so good that I barely understand 10% of it.


isn't that a text by robert greene? i think i've read it. yeah, mr 
greene is a mathematician, and they like it rigorous. but you don't need 
that level of understanding to use ambisonics. you don't have to 
understand electronics to use an amplifier, and you don't have to 
understand acoustics to use a microphone. some insight helps, and the 
more you know the better, but being able to build some piece of gear 
from scratch is not a prerequisite to get started.


check out the link i posted earlier, it tries to introduce the concept 
of spatial sampling to practical sound engineers. there's one 
(intentional) gap in the logic, in that it starts with the 
kirchhoff-helmholtz integral (which strictly speaking is the basis for 
wfs, not ambisonics) and then jumps to spherical sampling. it's not 100% 
kosher from a mathematical POV, but hopefully easier to understand. and 
as the order goes up, the area of correct reproduction expands, so that 
it ultimately approaches the KH surface from the inside.
if you're in a hurry, there are slides as well, which are a lot more 
compact: 
http://stackingdwarves.net/public_stuff/linux_audio/tmt10/TMT2010_J%c3%b6rn_Nettingsmeier-Higher_order_Ambisonics-Slides.pdf


best,

jörn



--
Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487

Meister für Veranstaltungstechnik (Bühne/Studio)
Tonmeister VDT

http://stackingdwarves.net

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Jörn Nettingsmeier]

On 07/10/2011 12:32 AM, dw wrote:

I was thinking more of recording in mono, computing the vectors in
various bands from the output of some large microphone array and then
encoding (the mono sound) into the required number of spherical
harmonics.


i don't think that's possible. imagine two similar instruments, one at 
0° and the other at 180°. once recorded in mono, they will be fused 
together irrevocably. you won't be able to separate them with the help 
of any vector metadata.



I doubt whether there is any advantage in determining the
vectors much better than a human listener can do, although not
necessarily in the same way.


the problem is that for each corner you cut, there is usually some 
source material that makes your approach fall flat on its face...



If nature can do 'it' with two ears, surely
it can't be too difficult with the benefit of a large array.


dangerous assumption. nature does it with two highly evolved and 
extremely non-linear ears, an elaborate panning, tilting and rolling 
mechanism and some very, very advanced signal processing.


next problem you face is that while rear and lateral localisation of the 
human hearing isn't good, frontal localisation is. so unless you want to 
assume your listener is glued to a screen, you need this degree of 
resolution everywhere. and it's a very high resolution indeed.


final nail in the coffin (for every system short of perfect sound field 
reproduction) is that auditory perception varies extremely between 
individuals, so whatever optimisation you do won't work for a number of 
people.



I am of the firm opinion that audiophiles do not deserve anything better
than the vinyl, stereo, and tweaks they have now, but it is still
interesting to see what is possible.


as long as they don't force cable and green felt marker discussions on 
me, i'm happy to see them happy. :)


--
Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487

Meister für Veranstaltungstechnik (Bühne/Studio)
Tonmeister VDT

http://stackingdwarves.net

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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Eric Benjamin]

Rober Greene wrote:
> There was a method developed by Finsterle 

Tell us more about it.  Is the method described elsewhere?  Is it embodied in a 
device, or software?  Who is Finsterle?

Eric



- Original Message 
From: Robert Greene 
To: Surround Sound discussion group 
Sent: Sat, July 9, 2011 8:22:04 PM
Subject: Re: [Sursound] the recent 2-channel 3D sound formats and their 
viability for actual 360 degree sound


There was a method developed by Finsterle that worked very well
indeed, much better than Trifield(which has always seemed to me
to have a serious "center detent".
Finsterle's method  had sound in the rear psychoacoustically
encoded not to sound in the rear but to solidify the front
images.
This worked very well in my experience
Robert

On Sat, 9 Jul 2011, Paul Hodges wrote:

> --On 09 July 2011 14:04 -0400 Marc Lavall?e  wrote:
> 
>> So, is it possible to adapt a stereo recording to play on a horizontal
>> ambisonics system, in order to get a better stereo image than with
>> conventional stereo? A kind of "restored stereo" experience that
>> ambisonics can provide because of its directional capabilities?
> 
> Two approaches that Michael Gerzon took are exemplified by the "Super Stereo" 
>mode of the early ambisonic decoders, and the later "Trifield" system using 
>three speakers; but neither of these is about attempting to generate a full 
>circle from the stereo signal.  A problem that arises, in any case, is that 
>the 
>result does depend strongly on the way the stereo recording was made - 
>coincident mics (e.g. Blumlein), spaced mics (e.g. Decca Tree), or a reliance 
>on 
>mixing from spot-mics.  As these record very different directional cues, a 
>single process can't be expected to handle them all equally effectively.
> 
> As for 5.1 - there are a number of useful decoders available which can be 
> used 
>to reproduce ambisonic signals using speakers set up for 5.1; but the 
>irregular 
>spacing means inevitably that the results are not as good in some directions 
>as 
>they could be with the same speakers more uniformly spaced. Playing 5.1 
>signals 
>through an ambisonic system is a matter of steering those signals as virtual 
>sources at the required angles in a B-format signal; as with stereo, nothing 
>is 
>added to the experience because there is nothing extra to be found - but the 
>reproduction will be less good to the extent that the sources expected when 
>the 
>5.1 mix was done are being less precisely reproduced.
> 
> Paul
> 
> -- Paul Hodges
> 
> 
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Robert Greene]

There was a method developed by Finsterle that worked very well
indeed, much better than Trifield(which has always seemed to me
to have a serious "center detent".
Finsterle's method  had sound in the rear psychoacoustically
encoded not to sound in the rear but to solidify the front
images.
This worked very well in my experience
Robert

On Sat, 9 Jul 2011, Paul Hodges wrote:


--On 09 July 2011 14:04 -0400 Marc Lavall?e  wrote:


So, is it possible to adapt a stereo recording to play on a horizontal
ambisonics system, in order to get a better stereo image than with
conventional stereo? A kind of "restored stereo" experience that
ambisonics can provide because of its directional capabilities?


Two approaches that Michael Gerzon took are exemplified by the "Super 
Stereo" mode of the early ambisonic decoders, and the later "Trifield" 
system using three speakers; but neither of these is about attempting to 
generate a full circle from the stereo signal.  A problem that arises, in 
any case, is that the result does depend strongly on the way the stereo 
recording was made - coincident mics (e.g. Blumlein), spaced mics (e.g. 
Decca Tree), or a reliance on mixing from spot-mics.  As these record very 
different directional cues, a single process can't be expected to handle 
them all equally effectively.


As for 5.1 - there are a number of useful decoders available which can be 
used to reproduce ambisonic signals using speakers set up for 5.1; but the 
irregular spacing means inevitably that the results are not as good in some 
directions as they could be with the same speakers more uniformly spaced. 
Playing 5.1 signals through an ambisonic system is a matter of steering 
those signals as virtual sources at the required angles in a B-format 
signal; as with stereo, nothing is added to the experience because there is 
nothing extra to be found - but the reproduction will be less good to the 
extent that the sources expected when the 5.1 mix was done are being less 
precisely reproduced.


Paul

--
Paul Hodges


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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Marc Lavallée]

Fons Adriaensen  a écrit :

> As to material produced for conventional speaker playback, some
> of it produces a 'nice' sound, with a clear spatial effect, as
> long as you are not trying to focus your attention on individual
> sources or instruments. Which is something I can't avoid doing
> being a trained sound engineer, but also something any musician
> or critical listener will do at some time.

I find it easier to focus on details with XTC. But it depends a lot on
the recordings. Some are horrible, others are wonderful. With
conventional stereo, I find that everything is equally smeared, like a
kind of glorified mono with a larger stage. I'm waiting for a pair of
very directional speakers that should (hopefully) help me enjoy
conventional stereo.

> What almost certainly *fails in major ways* will be e.g.
> 
> - opera (or other forms of stage drama) recordings meant for
> stereo listening (i.e. not the DVD productions which have all
> the singers at the center to match the video),

I have one recording of a Scarlatti opera that sounds very nice (and
detailed) with XTC. But usually I prefer mono for operas (listening on
the radio).

> - anything that has off-center bass (from ancient music
> with double bass flutes to reggea),

Why? I have no problem with off-center bass; I use 2 small speakers
with XTC and 2 subs with normal stereo.

> - many organ recordings, which when XTC-ed produce an organ
> that seems to be wandering all around, making me seasick.

True! I prefer mono or stereo for organ, or the real thing (in my
city there's a lot of good organs and a yearly festival)

XTC can do very strange things to bad stereo recordings, and there's
a fair amount of those in circulation. The worst I heard are recent
piano and harpsichord recordings that are considered masterworks by
critics. They were made to sound "glorious". XTC can reveal a lot of
bad tricks, and can destroy many mediocre recordings. Pop and jazz gigs
are a lot of fun with XTC. Anything with artificial reverb from the
80's is a catastrophe (what a terrible decade). Conventional stereo and
mono, on the other hand, are very forgiving. 

>> I understand your clinical point of view, but I don't consider the
>> act of listening to reproduced music as a scientific activity.  
>
> Agreed 100%. But the act of analysing and discussing the merits
> of technical systems to reproduce sound or music surely is a
> scientific activity, or at least something that should be done
> using a scientific mindset and avoiding marketing language and
> suggestive terminology. Such as presenting the way stereo works
> (by delivering both speaker signals to both ears) as a 'defect'
> which has to be 'cancelled'.

Ambisonics enthusiasts are also using strong words; to them, anything
not ambisonics (or "blumleinish") is flawed, and simple questions are
often received as direct attacks. 

I use XTC to improve some of my listening skills, not to replace all
other listening methods. I have nothing to sell, and I sometimes use a
home-made physical barrier because it's still the best XTC method.

Presenting ambisonics as a scientific tool, a sound engineering secret,
or a surround system for museums or stadiums, are not very good ways to
promote it to home listeners, especially considering the quasi-absence
of ambisonics material in circulation.

If you could help me understand spherical harmonics, I'd be a "MAG
fanboy" in no time. The best didactic resource I found is a very
strange article titled "Notes on Basic Ideas of Spherical Harmonics".
It's so good that I barely understand 10% of it.
--
Marc


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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Jörn Nettingsmeier wrote:


On 07/09/2011 10:19 PM, Stefan Schreiber wrote:


Fons Adriaensen wrote:


On Sat, Jul 09, 2011 at 02:04:21PM -0400, Marc Lavallée wrote:




The perceived "directional bandwidth" of stereo recordings is better
than what conventional stereo (with cross-talk) can reproduce.



This is again a game of words.

Most stereo recordings are made to be reproduced by two speakers,
seen by the listener at an angle of 60 to 90 degrees, and such that
the signals from either speaker reach both ears. That is the way it
is supposed to work. There is a solid theory behind this. Calling
this 'crosstalk (a term which has a negative connotation as a defect
of audio equipment), and the cure 'crosstalk cancellation' amounts to
gross intellectual dishonesty. The signals you find on the vast 
majority
of stereo records are _not_ meant to be delivered one-to-one to the 
ears.




And people listen to the same stuff via headphones?



yes, and that is a problem :)
you will find that a bit of artificial crosstalk greatly improves the 
spatial impression of traditional stereo recordings when delivered 
over headphones.



I am actually aware of this, but as you say, it is "a bit" of X-talk. My 
theory is that most commercial recordings are exctly something between 
60º and "separated channels".





As this seems to work, XTC can't be SO wrong.



whatever floats your boat. xtc has a certain effect on most material 
which most xtc users like, and that's fine.



Don't forget that RG would (righteously) argue that most stereo 
recordings are recordings which "stereo users" like, and that's 
fine.  :-)




the "localisation" of xtc'ed traditional stereo is similar to spaced 
omni miking, in the sense that it's kind of nice and spacey, but the 
result has nothing to do with reality, at all.
and you have to keep in mind that what you are hearing with xtc is not 
what the producer intends you to hear.



Now I am getting really impatient: A producer would probably mix 
something that works on "60º spaced speakers" AND headphones. O how do 
most people listen to music, nowadays? (Answer: On computers and on 
mobile devices. Safe bet.)




strictly speaking, xtc is only correct for binaural material (which, 
otoh, will be absolutely wrong when played back over stereo speakers).



Yes, I knew. I am unaware if every stereo recording is meant for 60º 
speakers, in fact a Blumlein recording is not, and many microphones have 
a barrier.


Just speaking as a layman...  :-D




and to comment on a previous remark about the turning of the head: 
with ambisonics, the point is not that the image doesn't collapse when 
you turn (that's really the most basic requirement), but rather that 
you gain additional information, because the soundfield is reproduced 
somewhat correctly in _all_ directions and you can benefit from your 
keener localisation sense in the frontal quadrant, turn your head and 
tune in to lateral sources. they will be reproduced just as 
convincingly as the frontal sound stage. that's a minor benefit as 
long as you're listening to the usual "stage in front" kind of music, 
but if you're a room acoustics nerd or you're into contemporary music 
with a somewhat wider sound stage, the advantage is quite palpable.


with xtc, head turning doesn't ever give you extra information. you 
just perceive the binaural (or not) signal in a different (and 
strictly speaking incorrect) way, which may have a pleasant effect. 
then again, it may not.




It is an advantage of surround speaker configurations (including 5.1) 
that you can turn your head, at least to some degree.


In fact, you expect this from a surround speaker array. You should be 
able to move your head, and you should be able to move around in the 
room. (Well, depending on the sweet spot.)



Best,

Stefan
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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Fons Adriaensen wrote:


On Sat, Jul 09, 2011 at 10:13:13PM +0100, dw wrote:

 

Care to send a clip of an impossible-to-sound-as-good-as-with-stereo  
recording for me to play with.
   



If it's anything I produced myself you'd just say I engineered
it to fail with XTC :-) Which indeed I could easily do...
 



In other words, please send me an MP3 file which I can't hear via 
headphones, but has to sound well on stereo speakers spaced at 60º.


As this is something easy and trivial, as you say...



Best,

Stefan Scheiber

P.S.: Apple will refuse to offer you track on iTunes, though.


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Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound

[Stefan Schreiber]

Jörn Nettingsmeier wrote:


On 07/09/2011 11:13 PM, dw wrote:


Care to send a clip of an impossible-to-sound-as-good-as-with-stereo
recording for me to play with.



well, this kind of stand-off isn't likely to lead anywhere. "sounds 
good" is very hard to define or even test.


i'm not terribly interested in applying xtc to standard stereo, 
because i know that perfect xtc is achived with headphones, and i 
don't like the imaging of stereo over headphones. 



But the main reason for in-head effects etc. is probably not related to 
XTC at all!


I don't like listening via headphones, but this is IMO not related to 
the stereo image. ( There are certain other problems which are not 
related to stereo, binaural or 5.1 via headphones, so it is not just an 
imaging problem.)



Listening to XTC stereo over speakers is actually quite different from 
listening via headphones, as you can move your head at least to a cetain 
degree.


A serious listening experience via headphones might require head 
tracking, unless we clamp the head once more.


Best,

Stefan


P.S.:
IF tonemasters would arduously work to deliver the best-possible 60º 
stereo mix WITH deliberate cosstalk, I don't think we would see all the 
folks run around with earphones.


Maybe I am wrong, but...:-P

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