Anyone who would like an introduction to spherical harmonics
expansions could have a look at this(which I wrote myself)
http://www.regonaudio.com/SphericalHarmonics.pdf
as an introduction for audio people.
It is perhaps worth noting that spherical harmonics
(and Fourier expansion of periodic
Of course this completely ignored the fact
that in blind testing years ago,
everyone preferred cassettes of vinyl
to vinyl itself(which ought to have
told people something about the recording
industry's recording practices).
Robert
On Sun, 23 Jan 2011, dave.mal...@york.ac.uk wrote:
On Jan 23
Actually, I think the remarks below represent a bit of
a misconception about stereo
playback. In actuality, if one used more speakers
one could make stereo playback better in the sense
that one could widen the spot in which it sounded
reasonably correct.
In actuality, if one sits absolutely
four inches away for example? Audio people
act as if the master were the word of God.
But the master is in fact usually lousy
Robert
On Mon, 24 Jan 2011, Ronald C.F. Antony wrote:
On 23 Jan 2011, at 23:52, Robert Greene wrote:
Of course this completely ignored the fact
that in blind testing
-in? Ideally it would be nice to have it available within the
plug-in architecture of the Logitech Squeezeserver that we use for
casual audio playback. There are even limited implementations of room
correction done in that manner.
Michael
On Thu, 24 Feb 2011 10:15:40 -0800 (PST), Robert Greene wrote
correction done in that manner.
Michael
On Thu, 24 Feb 2011 10:15:40 -0800 (PST), Robert Greene wrote:
I suppose that someone ought to mention-so I shall--
the Carver Sonic Hologram.
You can still find the devices around(they were
crosstalk cancellation processors).
They work really well, if you do
as much sense as saying that Lindberg discovered
France.
On Fri, 25 Feb 2011, Eero Aro wrote:
Robert Greene wrote:
I think this idea was invented by Christian Huygens and
Young and Fresnel. Once one knows that sound is a wave phenomenon,
there is nothing left to invent--except the details
it working with their speakers and rooms. The Lexicon Panorama mode
had similar problems.
Ralph Glasgal
www.ambiophonics.org
From: Robert Greene gre...@math.ucla.edu
To: Surround Sound discussion group sursound@music.vt.edu
Sent: Thu, February 24, 2011 1:15:40
I realize that the discussion is about perfection. But in
practice my experience with an Oscar(Sennheiser dummy head)
played back through head phones was that things like up and behind
off to one side a bit, all around in short, worked really well,
on headphones and with the generic pinnae of
Actually, the butterfly flap thing is not really good either.
In chaos, things do not cause other things. The system is
essentially noncausal.
This is a trick point. But if a system depends unstably
on its initial state, it makes no real sense to say that it
depends on its initial state at all
Re John L's remarks
I am not sure this is relevant to the interests of most
people on this list as such, but I do think it is absolutely
true that few people have a functioning proper surround set up.
As a High End audio reviewer, I know lots of consumers who
are interested in sound.
Here is a post that makes sense in the real world.
Of course it is intriguing to work out how
to create the impression of a mosquito circling around
your head. But it is really not important musically.
What is wrong with stereo?
1 It is all in front
2 It is too LITTLE. Real orchestras are 15
Maybe everyone who deserved to go to heaven went--but no one did so
no one is missing. On the other hand, my dogs are still here,
so I doubt that this happened.
Robert
On Sun, 22 May 2011, Sampo Syreeni wrote:
On 2011-05-22, Danny McCarty wrote:
The rapture did happen. You just can't tell
As it happens, I can get this for you in the sense
of making a photo copy of it--the library where
I work has this volume.
It will take a few days, however, since this
is a holiday weekend in the USA
But I can have it in a week or so and scan
it and send it by email to you, if no
one else gets
Yes that is it!
Incidentally, I would like to add a (nonmathematical)
point. I think dipoles are more or less a disaster for Ambisonics
Bass is one thing, but what dipoles mostly do is bounce sound off
the back walls(unless you were using them as subwoofers only)
in a way that creates
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
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
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
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
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
If you do not do something tricky with the amplifier--
and no commercial consumer audio amplifier intended for
universal use does this trickiness, or none I am aware of--
then the cable impedance operates as part of the amplifier
output impedance. This means that the amplifier
will not be flat
I found this message really intriguing since the rabbit is
really in an ad for Energizer batteries not Duracell.
One wonders why advertising is useful! I have had
exactly the same experience. The ads are memorable,
but what they are ads FOR is not.
Better than the original--who can forget the
All of this arises in my view from two simple things:
1 People in audio do not check things double blind
and
2 People in audio do not normalize things for frequency response
and do not do precision measurements of frequency response.
Point 1 is obvious. About point 2: Small shifts in frequency
Talk about mumbo jumbo!
Sounds to me as though all this(that is described) would do is to create
confusion.
If people like it, fine. But it is surely not suppressing HRTFs--
it is just presenting a sort of diffuse effect. The HRTFs
are still there--they are just operating on a confused and
RD's analysis was very interesting. But about Informantion wants to be
free: People certainly deserve protection for the value of their
intellectual work. But greed transforms this plausible principle
often enough into abuse.
Let me give an example: Scientific research papers and
Wonderful! The whole point of science is
to give the information to other people.
Otherwise, science is no different from
what Peter Hoeg says about it in Smilas Sense of Snow,
that it is inevitably about money.
Scientific information ought to be public domain.
Anything else is a cheat of the
I agree. Air absorption is substantive in concert halls
because the rooms are so large, so that the sound travels
a long way before finally dying out. This is a major effect.
Even a bright concert hall(comparatively bright) has
a considerable roll off of the top octave in its reverberant
field
I think there were a number of reasons
1 It took a long time for a medium to arrive that offered
a conveninent way to present a lot of channels. Actually,
while in principle CD did, in practice this was never
used. The surround schemes that came along that worked
commercially either involved
PS There is one more reason, which is less obvious and perhaps
not obvious at all to those of you in Europe.
Namely, Americans have never liked one point recording.
They have never liked Blumlein or ORTF(quasi one point) stereo
and they still do not.
Starting with the Bell Telephone Labs(as the
at 12:52:22PM -0700, Robert Greene wrote:
Surround in music has never been a hit in any form and it still
is not. Moreover most music is not really enhanced by it in the minds of
most people. Orchestral music benefits enormously--most of what you hear
in an orchestra concert is all around you
One of the things that is emerging here is(dare I say so)
that Ambisonics for music at home is just not such a good idea.
Attractive though it is mathematically--and it is very much that--
it is really impractical for home music.
Perhaps it is worthwhile to think for a moment about why.
My
I did not say it should(be played in front)! It just is.
Of course there are instances when antiphonal effects
are used, and very well they can work too.
But I think that using this sort of thing as a way
to persuade people they ought to have 16 channels
of playback or something is wrong
Actually, I think the ear/brain does not make
this distinction without pattern recogntion,
in other words, the height impression to the
extent that it arises from spectrum of the sound
depends on what the ear/brain expects the actual
sound to be. There is a similar effect about
frontal versus
I raised earlier the question of why Trifield is not available
to the general public.
Given that there are other people(e.g. J. Bongiorno in High End
and all kinds of things in home theater) offering
devices to synthesize a third channel--and that
lots of people already have a center channel
I don't think anyone thinks that! What people do think
is that Ambisonics needs some sort of commercial accesibility--
which it could get if discs were put out that provided not
abstract Ambisonics as it were but Ambisonics as decoded
to the 5.1 set up. The message was that no one (statistically
OK I thought that was a good idea, for people to say what they thought
was good and not good about Ambisonics. So here I go(first I guess
but my mother always said Act in haste, repent at leisure. I think
she meant it as cautionary but I have always taken it as advisory!).
Good
1 Elegant as
:44 PM, Robert Greene wrote:
I don't think anyone thinks that! What people do think
is that Ambisonics needs some sort of commercial accesibility--
which it could get if discs were put out that provided not
abstract Ambisonics as it were but Ambisonics as decoded
to the 5.1 set up. The message
Field Synthesis.
Not so good:
1) I frequently find that I have front/back confusion.
Let the debate continue.
- Original Message
From: Robert Greene gre...@math.ucla.edu
To: Surround Sound discussion group sursound@music.vt.edu
Sent: Sun, April 1, 2012 8:03:44 PM
Subject: Re: [Sursound
).
Dave
On 01/04/2012 10:20, Paul Hodges wrote:
--On 31 March 2012 18:34 -0700 Robert Greene gre...@math.ucla.edu wrote:
Of course music exists that is not in front. But the vast bulk of
concert music is not like that.
Sure; but what proportion of music are we happy to be unable to reproduce
Re marketing
I am not a marketing expert but it seems to me that if anyone
had really wanted Ambisonics to succeed, there would
have been
1 presentations at shows for example. I have
over the years encountered exactly one, by Meridian. Period.
And
2 there would have been low priced or free demo
, 2012, at 8:34 AM, Robert Greene wrote:
It may be old but it is still all but universal
in acoustic concert music.
I think it is disingenuous to say that it is not.
How many symphony concerts have you been to
recently where the orchestra surrounded the audience.
The other way around, sure.
But I
Part of the point must surely be to reach the public
eventually? Or is that somehow sort of declasse?
Robert
On Mon, 2 Apr 2012, Richard Dobson wrote:
On 02/04/2012 16:34, Robert Greene wrote:
It may be old but it is still all but universal
in acoustic concert music.
Maybe; but acoustic
Incidentally, I may come across as interested
only in classical music(true) but popular
music is the same way. Anyone watch the Country Music
awards show(you cannot get more grass roots popular than that).
See a lot of country music singers doing antiphonal calling
from all over the auditorium?
This sounds plausible except that it is clearly completely
wrong. Hunger Games has grossed about one quarter billion
dollars in a few weeks worldwide. Don't talk about small
taking over!
Small is there, all right. But large is still there, too.
Taylor Swift's Speak Now sold over a million in the
Thanks for the information.
But here is my question in more precise form:
Suppose you do a recording with ORTF(which
of course has its own set of problems).
Suppose you record a source that is say 15 degrees
left of center. and that the source is a pistol shot(an impulse).
Now the impulse will
in stereo reproduction.
I will do some calculations on ORTF stereo so that I can understand it better.
- Original Message
From: Robert Greene gre...@math.ucla.edu
To: Surround Sound discussion group sursound@music.vt.edu
Sent: Mon, April 2, 2012 1:44:28 PM
Subject: Re: [Sursound
the WaterLily Mahler 5 a benchmark for all future orchestral
recording. Depend on who you ask, I guess.
Robert
On Mon, 2 Apr 2012, Robert Greene wrote:
Sorry you don't like it. Apparently you do not like
the sound of the St Petersburg orchestra since of
course we did absolutely nothing to alter
a case in point - in the West (and probably
increasingly in it's home countries) Gamelan is usually presented
frontally (even we usually do that) but this is _not_ correct
traditionally.
Dave
On 2 April 2012 16:34, Robert Greene gre...@math.ucla.edu wrote:
It may be old but it is still all
I agree. My appeal for material to listen to
was not intended as a call to get Apple to take
over. The blood curdles.
Robert
On Tue, 3 Apr 2012, Marc Lavall?e wrote:
I would fear an applelization of ambisonics. Apple could impose its
own ok format (probably as a CAF chunk specification) with
Thanks everybody for the links and in particular the
calculation of models link. I shall work on that one
I know the Lipshitz paper well, but it seems that
experts disagree. James Johnston has told me
a number of times for example that he thinks
getting those time cues from ORTF is really
I disagree with this. I suppose for some things like
pop vocals that do not have a natural acoustic venue
surrounding them, surround is not helpful.
But for large scaled acoustic music like orchestral
music(which of course some people here would
dismiss as a niche market) it really does help
I think that the idea that surround is not good enough
for music , good enough to matter, really does
not make sense. This is more or less like restricting
the idea of music to what works well enough in stereo
to be all right. But that is not all music, and indeed
for example it does not include
Being doctrinaire is really not a substitute for thinking.
Of course no reproduced music at home is going to be
identical to live experience. No one suggested
it was. But one could get closer.
And it is just silly to say go to the performance.
The music played , even in major cities,
is a very
This is very unlikely to be true, that one can justify
getting a new TV to save electricity for the sake of the world.
To save on your own bills will also take a very long time.
People seldom do the arithmetic on this. When the first
gas crisis occurred(in the 1970s) I did some calculation
of
Interesting indeed, but not new. I think the Unicorn
Fenby Legacy(Music of Delius), the part that was
done with the Soundfield mike, is one of the
finest of all stereo recordings of an orchestra.
For naturalness of sound, it is unbeatable and
hard for anything else to equal in my view.
Robert
Excellent! Most serious manufacturers seem to feel thatthe way to make an
inexpensive speaker is to take the top two thirds of a more expensiveone.
But of course it is a kind of convention of High End audio that
warmth and so on are really not importnat nor perhaps even desirable
Cf my guest
I agree. Time confusion in stereo(as generated by spaced omnis)
is far from being the same thing as spatially diffuse field sound.
This is the real reason stereo sounds wrong as far as I am
concerned. No offense to people who like spatial music
but the music I like happens in front. What does
Re dynamic range of orchestras.
For recording one needs more than CD standard 16 bits because
one never knows when some instantanteous peak may stick
way out and clip nastily if one does not have a lot of headroom.
Thank goodness for 24 bits!
But seriously, no orchestral music really has more
You can find a readable(I hope) introduction to spherical
harmonics on my website
www.regonaudio.com
Robert
On Thu, 24 May 2012, Augustine Leudar wrote:
Hi,
I know what I need to do - I just want to find out why Im doing it. The
components were not expensive at all - the mic is already built
Could I point out that in fact one does not
know what auditory reality is like for other
people whether or not they are hearing impaired?
One supposes it is similar. And structurally
it is similar--people tend to hear sound in the
same locations under given circumstances.
But literal sensation
The initial meessage is also in my view something of a misconception of
the meaning of perfect pitch
--which ought to be called absolute pitch, since there is nothing
perfect about it(no one has perfect resolution of pitch nor
of anything else!).
Absolute pitch is about MEMORY. Lots of
I have not had a chance to look at this in detail,
but one point seems worth noting in advance:
Such a conversion is in the literal sense
impossible. Stereo is a system with two
degrees of freedom. Horizontal Ambisonics
has three. One can Ambisonics into stereo
(losing information in the
I used to bring this stuff up as a reason why early
CD did not sound good--that there were possible
nonlinearities that made the missing content
above 21 kHz actually missed.
Onkyo had a player that put content in above
21k that was only vaguely related to
the inut signal! Sounded good too.
But
It is rather alarming how insubstantial it all is--
google ,facebook, apple selling gadgets that are
really quite useless and google and facebook
making money on ads and no other way(google
sells how far up the search list you are but
that is ad stuff too in effect)
The whole USA and a good deal
This is funny but it is of course wrong,
I like facebook a lot, but I dislike text messages,
and so on. Which general types of things one likes
may develop early, but the details are not
set in stone. This kind of thing is
an excuse for all kinds of bad stuff
that is supposed to be progress but
video on the subject: http://wimp.com/mindreader/
Ronald
On 8 Oct 2012, at 20:24, Robert Greene gre...@math.ucla.edu wrote:
This is funny but it is of course wrong,
I like facebook a lot, but I dislike text messages,
and so on. Which general types of things one likes
may develop early
This seems to me somewhat exaggerated(the remarks about stereo and the
center image). Sure, the center phantom image
generated as a sum of two identical L/R signals sounds a little different.
But little is the operative word. The correction for this fairly small
(Meridian used to have it up
automatically.
More than an afternoon but less than a week of construction time
I would guess.
Have fun!
Robert
On Fri, 19 Oct 2012, Paul Hodges wrote:
--On 19 October 2012 07:41 -0700 Robert Greene gre...@math.ucla.edu
wrote:
there is no real reason to want such a thing.
I have an electronic
The idea actually existed--dBX made one(I think it was they)
for commercial /consumer sale
Robert
On Sat, 20 Oct 2012, Neil Marcia Adams wrote:
Again with txt only (thank you Martin)
The late Dick Campbell designed a dodecahedron loudspeaker. Close?
This is absolutely true. My late first wife
heard stereo as two separate speakers no
matter how well the speakers worked for others.
She liked mono a lot better.
Surround sound was a n ightmare from her viewpoint--
all those speakers playing from different directions
each on heard individually.
Dont pay any attention to this about intensity and the
Doppler shift for moving objects, would be my
suggestion. It is almost all
wrong. ELC is mistaken here.
See my public post please.
Robert
On Mon, 25 Feb 2013, etienne deleflie wrote:
ELC: Visual cues may play part in this ability,
I think one can figure out something here without too much mathematical
analysis about what is missing in first order.
It is similar to what is missing in Blumlein stereo.
Namely if a hard transient occurs say 30 degrees left of center,
the associated wavefront arrives at the left ear before
it
it would arise from the four signals of B format)
On Fri, 26 Apr 2013, Sampo Syreeni wrote:
On 2013-04-25, Robert Greene wrote:
Namely if a hard transient occurs say 30 degrees left of center, the
associated wavefront arrives at the left ear before it arrives at the right
ear.
Except that what
far from 440! (which I suppose was the original
point). Piano (equal temp.) pitch is a bit disconcerting
but there is so much good music for piano one
just learns to live with it.
Robert
On Thu, 25 Apr 2013, David Pickett wrote:
At 20:35 25-04-13, Robert Greene wrote:
Not nearer--exactly! 440
at 06:33:47PM -0700, Robert Greene wrote:
To my mind it makes not much sense to suppose that the first order
reconstruction is correct in a neighborhood of the listener
but higher order is correct in a larger neighborhood--not literally
correct. This seems metaphysically impossible. Where
Indeed(to SS's message) And real analytic systems
do not exist in the real world. Unless you believe
in complete pre-destination in the religious sense,
that God planned everything infinitely long ago
and arranged that things were then what they would
have to be so that their analytic
write to me directly and I shall email
them a copy(or you can find the Math Monthly in
university libraries).
All the best
Robert
On Sat, 27 Apr 2013, Robert Greene wrote:
Indeed(to SS's message) And real analytic systems
do not exist in the real world. Unless you believe
in complete pre
2013, Robert Greene wrote:
Sorry--turns out that that link lets
you read the whole thing(as opposed to the
first page) only if you are a Jstor subscriber.
(Eventually the academic world will
figure out that all information ought
to be public access--but not yet apparently)_
Anyone who finds
I think I did not make myself clear.
Of course in those live versus canned experiments(also with AR)
reverberation tended to make things sound pretty much the same
to smooth out errors and so on.
But in fact, if one records musical instrument with a mike
and plays it back with a speaker has no
Even dead concert halls in the relative sense
have a lot of reverberation. A really dead hall
still has a 1 second reverberation time say
and most of what you hear in the audience is still
reverberant sound.
Robert
On Mon, 20 May 2013, David Pickett wrote:
At 00:50 18-05-13, Robert Greene
the Wharf. ones as well)
Robert
On Tue, 21 May 2013, David Pickett wrote:
At 12:16 21-05-13, Robert Greene wrote:
Even dead concert halls in the relative sense
have a lot of reverberation. A really dead hall
still has a 1 second reverberation time say
and most of what you hear in the audience
Sorry! I read the wrong volume! RFH is actually 21,960.
This gives critical distance ~ 7 meters.
(not that this changes my basic point but just for the record)
Robert
On Wed, 22 May 2013, Robert Greene wrote:
No. But the fact that a hall sounds
anechoic or nearly so does not mean
Didn't Lauridsen propose and experiment with
stereo playback done this way--with a mono signal
in the center and a diffference signal produced by a edgeon mounted
dipole?
Robert
On Wed, 22 May 2013, J?rn Nettingsmeier wrote:
Hi Ray,
On 05/22/2013 01:24 AM, revery wrote:
Hello j?rn,
I do not understand the last bit of this message below at all.
There is no such thing as a signal that is limited
in bandwidth and in time--not if limited
means actually 0 outside a finite interval
in both cases. This is a basic result of Fourier
analysis.
This kind of signal does not exist, not
This is for sure!
The legendary Mercuries(three spaced omnis and nothing else)
and their ilk
are completely
unconvincing to anyone who listens to them impartially--
there is no there there.
But the whole nation of the USA has ignored this obvious
fact for ..well pretty much forever.
Once on
This whole discussion is to my mind a living
illustration of why no progress to speak of ever
occurs in audio. Nothing is made precise,
no one does any experiments on what happens
to sound like what was there, everyone just
talks about what sounds nice to them or what
sounds like what they think
I apologize if people took offense. But the issue is serious.
It is surely acceptable if people want to make recordings
that do not sound like what was really there. This does
not interest me personally all that much, but to each his own
artistically.
But surely no one would argue that this
that it is
for example the signal that gives the best identification of which
loudspeaker is which when comparing blind two similar but different
speaker.
Robert
On Wed, 3 Jul 2013, David Pickett wrote:
At 06:31 3/7/2013, Robert Greene wrote:
Variations from reality ought surely to be based on knowing
how
/2013 05:31, Robert Greene wrote:
If people want to treat recording as a pure art form
where one simply judges the results on aesthetic grounds.
it would be hard to say that was wrong. But it surely
takes recording out of the realm of science.
I am not sure that recording is a science per se
WHat a lot of ado. I am not talking about
understanding people. I am just asking :
If you use mike technique x to record a pink
noise source in position y , what does the result
sound like on playback?
This is a simple question. It is obviously
relevant to what recording sound like in terms
of
people can actually obtain?
Localization--lots of literature and Boyk's recording
Timbre--sources please?
Robert
On Wed, 3 Jul 2013, J?rn Nettingsmeier wrote:
On 07/03/2013 06:31 AM, Robert Greene wrote:
I apologize if people took offense.
fwiw, i did not take offense at your clear preference
starts to look for it
and look at it hard. Even the localisation literture
is not all that convincing in detail as far
as microphone technique is concerned, though there
is a good bit of it. And a lot of it is contradicted
by other parts of it.)
Robert
On Fri, 5 Jul 2013, Robert Greene wrote
the excess quoting deleting text is a job. Thanks!
On Jul 5, 2013, at 1:04 PM, Robert Greene gre...@math.ucla.edu wrote:
I should add that this is not academic for me.
From (nonscientific) personal experience, I
have formed the impression that spaced mike techniques
color instrumental sound
This seems sensible to me. Also, it is part of
my basic hope, that one could come to understand
exactly what one should do to make (a) below
as accurate as possible.
However, the description of (a) as sterile is something
I would take issue with. I like the sound of real
music. It does not
not been at all obvious - and I'm sure everyone else who's done any
recording will have observed the same.
Dave
On 5 July 2013 17:20, Robert Greene gre...@math.ucla.edu wrote:
Hugely long. But one point cries out for comment:
It is simply nonsense to say that it would not
be useful to have
Decades ago, I was working on a project to find the best
way to equidistribute a large number of points on a sphere.
We were looking for random unit vectors.
(This had to do with choosing random orientations for a pot
containing a seed to see if the seed would sprout and grow
without benefit
an obvious existence.
Robert
On Thu, 11 Jul 2013, Michael Chapman wrote:
Robert Greene wrote :
...
If you need more points, then
there is no canonical choice(and no one is going to discover
any more Platonic solids--there aren't any more!).
...
Sorry to start that one ... it was basically
Are you asking how to figure out the angles or how to arrange to
hold the speakers in position?
One pattern you could use with 30 instead of 32 speakers would be to put
speakers at the midpoints of the edges of a regular dodehedron. (there are
30 edges). This is a quite regular pattern though
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