Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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! ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
[Sursound] Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
Hi, Date: Mon, 25 Jul 2011 08:24:55 - From: Richard Lee rica...@justnet.com.au 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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, -- FA ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
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 +358-50-5756111, 025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 gre...@math.ucla.edu To: Surround Sound discussion group sursound@music.vt.edu 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 the Soundfield mike could not be expected
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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. -- 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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? -- 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
[Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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.. ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 de...@iki.fi 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 DNR.) 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
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 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 de...@iki.fi 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,
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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. ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
Hi again, Date: Thu, 21 Jul 2011 12:45:45 - From: Richard Lee rica...@justnet.com.au 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 DNR.) 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 dave.mal...@york.ac.uk 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 netti...@stackingdwarves.net 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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. :) -- Bearcat M. Şandor Cell: 406.210.3500 Jabber/xmpp/gtalk/email: bear...@feline-soul.net MSN: bearcatsan...@hotmail.com Yahoo: bearcatsandor AIM: bearcatmsandor ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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. sound of coffee being expelled through the nose 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
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
On 18/07/2011 19:01, Fons Adriaensen wrote: On Mon, Jul 18, 2011 at 07:27:26PM +0200, Jörn Nettingsmeier wrote: sound of coffee being expelled through the nose 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 -- 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 Musichttp://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/; */ /*/ ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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. sound of coffee being expelled through the nose 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,
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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. sound of coffee being expelled through the nose 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
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
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 st...@mail.telepac.pt 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. ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
On 07/12/2011 03:24 PM, Tom Jordaan wrote: On Tue, 12 Jul 2011 01:56:08 +0100, Stefan Schreiber st...@mail.telepac.pt 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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. ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 netti...@stackingdwarves.net 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%
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ) ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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... :-) ) ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 pwh-surro...@cassland.org To: Surround Sound discussion group sursound@music.vt.edu 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 netti...@stackingdwarves.net 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
Stefan Schreiber st...@mail.telepac.pt 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 gre...@math.ucla.edu To: Surround Sound discussion group sursound@music.vt.edu 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 m...@hacklava.net 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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'. ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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, ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
Jörn Nettingsmeier netti...@stackingdwarves.net 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 already read your aticles, they are really
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
Robert Greene gre...@math.ucla.edu 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 f...@linuxaudio.org 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, -- FA -- next part -- An HTML attachment was scrubbed... URL: https://mail.music.vt.edu/mailman/private/sursound/attachments/20110710/286b6ae2/attachment.html ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 http://en.wikipedia.org/wiki/Non-sinusoidal_waveform, most typically encountered in electronics http://en.wikipedia.org/wiki/Electronics and signal processing http://en.wikipedia.org/wiki/Signal_processing. An ideal square wave alternates regularly and instantaneously between two levels. Its stochastic counterpart is a two-state trajectory http://en.wikipedia.org/wiki/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 -- next part -- An HTML attachment was scrubbed... URL: https://mail.music.vt.edu/mailman/private/sursound/attachments/20110710/6c9454a5/attachment.html ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
Stefan Schreiber st...@mail.telepac.pt 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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. -- next part -- An HTML attachment was scrubbed... URL: https://mail.music.vt.edu/mailman/private/sursound/attachments/20110710/288b5990/attachment.html ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
Stefan Schreiber st...@mail.telepac.pt a écrit : Now come on, a square wave is not about music! Iannis Xenakis would not agree with you... -- Marc ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
Marc Lavallée wrote: Stefan Schreiber st...@mail.telepac.pt 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 -- next part -- An HTML attachment was scrubbed... URL: https://mail.music.vt.edu/mailman/private/sursound/attachments/20110710/90a6b180/attachment.html ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
dw surso...@dwareing.plus.com 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
On 10/07/2011 19:36, Marc Lavallée wrote: dwsurso...@dwareing.plus.com 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
On 07/10/2011 06:14 PM, Marc Lavallée wrote: Jörn Nettingsmeiernetti...@stackingdwarves.net 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 st...@mail.telepac.pt 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 --
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 surso...@dwareing.plus.com 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
Stefan Schreiber st...@mail.telepac.pt 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. -- Marc ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
Jörn Nettingsmeier netti...@stackingdwarves.net 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound _ 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 -- next part -- An HTML attachment was scrubbed... URL: https://mail.music.vt.edu/mailman/private/sursound/attachments/20110710/a1727017/attachment.html ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
ML: Maybe it can; is there a way to up convert non-ambisonics recordings to horizontal ambisonics? If you down sample a 48kHz recording to 16kHz what happens? All the audio information above 8kHz is lost right? If you up convert back to 48kHz can you recover the bandwidth lost? No. You just have a large file. Everything from 8kHz up is still missing... (where would it come from? It's GONE!). The concept is the same for directionality. Once you have selected the dimensional format (stereo, ambi, 5.1, etc) any format with a lesser directional 'bandwidth' will be rendered 'stuck'. The concept of up-converting dimensionally can only be a smoke and mirrors illusion at best. - Neil On 7/9/2011 1:07 PM, Marc Lavallée wrote: Fons Adriaensenf...@linuxaudio.org a écrit : And *if* I turn my head, for whatever reason, and the illusion collapses, I'm not impressed... I just tried turning my head while listening to XTC. I can turn it more than 45 degrees in both directions without destroying the stereo image. So if turning the head is part of the localization process, it does also work with XTC (to some extent). XTC brings out a better and larger stereo image from conventional stereo recordings, just by inserting a filter in the reproduction path and by using two small frontal speakers (not four or more speakers all around me as required by ambisonics). That's already impressive. I still don't know from experience if ambisonics is better than XTC for other than practical and ideological reasons. I hope to have a second epiphany with ambisonics, because it requires more investments and efforts to install a working system at home. I only heard a few minutes of ambisonics (rendered with the Harpex filter on a horizontal/hexagonal speakers setup), and it was interesting... I would be impressed if ambisonics could provide a better listening experience from stereo and/or 5.1 recordings. Maybe it can; is there a way to up convert non-ambisonics recordings to horizontal ambisonics? -- Marc ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
Neil, I used the wrong words. Please excuse my up-converting nonsense, and let me ask again. The perceived directional bandwidth of stereo recordings is better than what conventional stereo (with cross-talk) can reproduce. 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? Another example: there are ways to listen to ambisonics on 5.1 systems, but is it possible to listen to 5.1 recordings on a horizontal ambisonics system? Neil Waterman neil.water...@asti-usa.com a écrit : ML: Maybe it can; is there a way to up convert non-ambisonics recordings to horizontal ambisonics? If you down sample a 48kHz recording to 16kHz what happens? All the audio information above 8kHz is lost right? If you up convert back to 48kHz can you recover the bandwidth lost? No. You just have a large file. Everything from 8kHz up is still missing... (where would it come from? It's GONE!). The concept is the same for directionality. Once you have selected the dimensional format (stereo, ambi, 5.1, etc) any format with a lesser directional 'bandwidth' will be rendered 'stuck'. The concept of up-converting dimensionally can only be a smoke and mirrors illusion at best. - Neil On 7/9/2011 1:07 PM, Marc Lavallée wrote: Fons Adriaensenf...@linuxaudio.org a écrit : And *if* I turn my head, for whatever reason, and the illusion collapses, I'm not impressed... I just tried turning my head while listening to XTC. I can turn it more than 45 degrees in both directions without destroying the stereo image. So if turning the head is part of the localization process, it does also work with XTC (to some extent). XTC brings out a better and larger stereo image from conventional stereo recordings, just by inserting a filter in the reproduction path and by using two small frontal speakers (not four or more speakers all around me as required by ambisonics). That's already impressive. I still don't know from experience if ambisonics is better than XTC for other than practical and ideological reasons. I hope to have a second epiphany with ambisonics, because it requires more investments and efforts to install a working system at home. I only heard a few minutes of ambisonics (rendered with the Harpex filter on a horizontal/hexagonal speakers setup), and it was interesting... I would be impressed if ambisonics could provide a better listening experience from stereo and/or 5.1 recordings. Maybe it can; is there a way to up convert non-ambisonics recordings to horizontal ambisonics? -- Marc ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
--On 09 July 2011 14:04 -0400 Marc Lavallée m...@hacklava.net 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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. XTC will work (within some limits) on binaural recordings, and it produces a sort of spatial effect on some of those that are badly engineered for speaker reproduction, e.g. using widely spaced omni mics as the main source. It also can provide some 'spatiality' on TV sound, helped by the fact that when watching a screen in front you are unlikely to face other directions than the one to the screen. 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? Starting from stereo there is little Ambisonics can do. One some (mostly classical music) recordings, you can add either algorithmic or convolution reverb to mimic the acoustics of a real concert hall, and this can be quite effective. An AMB reproduction rig can also do better room correction than would be possible with just two speakers. Ciao, -- FA ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
On Sat, Jul 09, 2011 at 09:19:07PM +0100, 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? The fact that many recordings intended for speaker reproduction (in particular those using panned mono sources) work also on headphones is remarkable, and an illustration of how adaptive our hearing can be. But almost always you can improve the results on headphones by introducing the sort of 'crosstalk' that a speaker system would produce. Either using HRTF, or in the simplest case a highpass filter on the difference signal (which is a crude approximation). The exceptions are binaural recordings of course, which should be left as they are. The simple fact is that there is *fundamental* difference between signals supposed to be correct when delivered 1-to-1 to the ears, and those intended to be reproduced using two speakers. The vast majority of available records are of the second kind. Ciao, -- FA ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
Totally agree 100%. Personally I would state that I have a totally different experience when listening to the same recordings via loudspeakers versus headphones. Headphones rarely give me a the orchestra/band is in front of me presentation (and no it is not a function of cheap or crappy headphones... I have some nice Sennheiser HD600's amongst others), but tend to spread the sound across my head (hard to describe), whereas the same recordings presented via speakers has a nice soundstage in *front* of me. - Neil On 7/9/2011 4:38 PM, Fons Adriaensen wrote: On Sat, Jul 09, 2011 at 09:19:07PM +0100, 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? The fact that many recordings intended for speaker reproduction (in particular those using panned mono sources) work also on headphones is remarkable, and an illustration of how adaptive our hearing can be. But almost always you can improve the results on headphones by introducing the sort of 'crosstalk' that a speaker system would produce. Either using HRTF, or in the simplest case a highpass filter on the difference signal (which is a crude approximation). The exceptions are binaural recordings of course, which should be left as they are. The simple fact is that there is *fundamental* difference between signals supposed to be correct when delivered 1-to-1 to the ears, and those intended to be reproduced using two speakers. The vast majority of available records are of the second kind. Ciao, ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
On 09/07/2011 21:38, Fons Adriaensen wrote: On Sat, Jul 09, 2011 at 09:19:07PM +0100, 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? The fact that many recordings intended for speaker reproduction (in particular those using panned mono sources) work also on headphones is remarkable, and an illustration of how adaptive our hearing can be. But almost always you can improve the results on headphones by introducing the sort of 'crosstalk' that a speaker system would produce. Either using HRTF, or in the simplest case a highpass filter on the difference signal (which is a crude approximation). The exceptions are binaural recordings of course, which should be left as they are. The simple fact is that there is *fundamental* difference between signals supposed to be correct when delivered 1-to-1 to the ears, and those intended to be reproduced using two speakers. The vast majority of available records are of the second kind. Ciao, Care to send a clip of an impossible-to-sound-as-good-as-with-stereo recording for me to play with. ps. You misunderstand the nature of my A-HYBRID filter, I think. I certainly hope so. pps. I am sure M Gerzon knew that ambisonics (low order) has theoretical sweet spot the size of a pea, but it still sounds good to some people, His fans are still as self-righteous as ever. ppps How are higher-order microphones coming aloing these days, or are we still happy truncating the infinite series at one order above an omni? ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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. and before you ask: i don't like the imaging of headphones bent outwards so as to benefit from my pinna filters, either. speaker xtc can only be worse than headphones. ps. You misunderstand the nature of my A-HYBRID filter, I think. I certainly hope so. i've browsed the readme on your site - is there some more in-depth information about this filter somewhere? pps. I am sure M Gerzon knew that ambisonics (low order) has theoretical sweet spot the size of a pea, but it still sounds good to some people, His fans are still as self-righteous as ever. i could imagine way worse things than being called a MAG fanboy. there has been very constructive discussion in the past about why first-order works way better than it obviously should, and what its limits are. this exchange however doesn't quite cut it in the constructive department. ppps How are higher-order microphones coming aloing these days, or are we still happy truncating the infinite series at one order above an omni? higher order microphones work in principle, but are nowhere near as pleasant as simpler stereo microphones. in addition to coloration problems, they suffer from noise problems due to the high gains required. -- Jörn Nettingsmeier Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487 Meister für Veranstaltungstechnik (Bühne/Studio) Tonmeister VDT http://stackingdwarves.net ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
On 09/07/2011 22:28, 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. and before you ask: i don't like the imaging of headphones bent outwards so as to benefit from my pinna filters, either. speaker xtc can only be worse than headphones. ps. You misunderstand the nature of my A-HYBRID filter, I think. I certainly hope so. i've browsed the readme on your site - is there some more in-depth information about this filter somewhere? I certainly hope not, apart from what I explained to Fons here, about the one I gave away , which was 'HYBRID'. I think I may 'disappear from the face of the earth' again, shortly. I've had enough already. ps. I am sure M Gerzon knew that ambisonics (low order) has theoretical sweet spot the size of a pea, but it still sounds good to some people, His fans are still as self-righteous as ever. i could imagine way worse things than being called a MAG fanboy. there has been very constructive discussion in the past about why first-order works way better than it obviously should, and what its limits are. this exchange however doesn't quite cut it in the constructive department. So how does this 'human energy-vector-detector work then? It is not the being a fan that I object to. I am a bit of a fan myself. You never objected to the non-constructive and rude comments of others.. ppps How are higher-order microphones coming aloing these days, or are we still happy truncating the infinite series at one order above an omni? higher order microphones work in principle, but are nowhere near as pleasant as simpler stereo microphones. in addition to coloration problems, they suffer from noise problems due to the high gains required. What you need is a 'virtual' high-order microphone. ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
On 07/09/2011 11:49 PM, dw wrote: On 09/07/2011 22:28, Jörn Nettingsmeier wrote: ps. I am sure M Gerzon knew that ambisonics (low order) has theoretical sweet spot the size of a pea, but it still sounds good to some people, His fans are still as self-righteous as ever. i could imagine way worse things than being called a MAG fanboy. there has been very constructive discussion in the past about why first-order works way better than it obviously should, and what its limits are. this exchange however doesn't quite cut it in the constructive department. So how does this 'human energy-vector-detector work then? ok'ish. ppps How are higher-order microphones coming aloing these days, or are we still happy truncating the infinite series at one order above an omni? higher order microphones work in principle, but are nowhere near as pleasant as simpler stereo microphones. in addition to coloration problems, they suffer from noise problems due to the high gains required. What you need is a 'virtual' high-order microphone. the approach i'm exploring is this: http://stackingdwarves.net/public_stuff/linux_audio/tmt10/TMT2010_J%c3%b6rn_Nettingsmeier-Higher_order_Ambisonics.pdf skip the intro and jump to section 5. i used to think that this kind of hack is not really conceptually elegant (it isn't - nothing beats the simple beauty of a sound field microphone). but then i learned about all the unholy hacks that are routinely being employed by respected record labels to produce their (very nice sounding) surround recordings. i have been very relaxed about conceptual purity ever since. but for my work, i still want to have a plausible theory first and then see what can be done in practice. i dislike stuff that sounds nice whose proponents can't really explain why :) but that's a personal spleen of mine, not a snide remark at xtc in general. best, jörn -- Jörn Nettingsmeier Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487 Meister für Veranstaltungstechnik (Bühne/Studio) Tonmeister VDT http://stackingdwarves.net ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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... I've been listening to XTC using all processors I know of, in at least four very different rooms, and using all sorts of source material. Some things sound rather well: e.g. binaural recordings made using a dummy head, or using similar techniques such as closely spaced omnis with some baffle or disk between them. But those sound terrible on speakers if not processed, so that is not the kind of material most people would encounter. 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. 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), - anything that has off-center bass (from ancient music with double bass flutes to reggea), - many organ recordings, which when XTC-ed produce an organ that seems to be wandering all around, making me seasick. ps. You misunderstand the nature of my A-HYBRID filter, I think. I certainly hope so. Then I hope you will explain it. pps. I am sure M Gerzon knew that ambisonics (low order) has theoretical sweet spot the size of a pea, but it still sounds good to some people, In fact first order AMB has some perception merits that are worse than for conventional stereo. Its great advantage is that it is surround *wihout any preferred directions*. Which makes for a very natural effect, even if the 'sweet spot' can be small. But it's never as restricted as it is for XTC. His fans are still as self-righteous as ever. Some of his fans hate me because I (and some others) have pointed out the limits of first order and moved on to higher order AMB, which is where things really start to work even in real-life and even in really adverse conditions. ppps How are higher-order microphones coming aloing these days, or are we still happy truncating the infinite series at one order above an omni? There are none ATM that can produce full frequency range higher order, and I doubt there will ever be. But we don't really need them either. Ciao, -- ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
Fons Adriaensen f...@linuxaudio.org a écrit : 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. I understand your clinical point of view, but I don't consider the act of listening to reproduced music as a scientific activity. Each time a playback occurs, it can be a new creation, not always a perfect repetition of past events. I admire the virtues of hi-fidelity, but I don't have the required budget (and mindset) to play this game. Most honest people are listening to stereo in any possible ways, including some twisted people who enjoy stereo with XTC. :-) XTC will work (within some limits) on binaural recordings, and it produces a sort of spatial effect on some of those that are badly engineered for speaker reproduction, e.g. using widely spaced omni mics as the main source. I never experienced convincing 3D with binaural recordings, either with headphones or XTC. Many stereo recordings are better than binaural recordings. It also can provide some 'spatiality' on TV sound, helped by the fact that when watching a screen in front you are unlikely to face other directions than the one to the screen. True: XTC is not ideal for dancing. Starting from stereo there is little Ambisonics can do. One some (mostly classical music) recordings, you can add either algorithmic or convolution reverb to mimic the acoustics of a real concert hall, and this can be quite effective. An AMB reproduction rig can also do better room correction than would be possible with just two speakers. Interesting. The same trick is used with ambiophonics. What I'd like to avoid is to install those distinct setups: - conventional 60 degrees stereo - stereo with XTC - 5.1 and 7.1 - ambiophonics (with 4 speakers) - ambisonics Ambisonics is often described as THE grand unified theory of audio, but it's just one more. I accept it as one of the best, even if I don't understand its strange maths. I'd really like to understand that spherical harmonics business, but I'd have to go back to school... -- Marc ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
On Sat, Jul 09, 2011 at 06:58:29PM -0400, Marc Lavallée wrote: 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'. Ciao, -- FA ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 -- next part -- An HTML attachment was scrubbed... URL: https://mail.music.vt.edu/mailman/private/sursound/attachments/20110710/fade7e3e/attachment.html ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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 -- next part -- An HTML attachment was scrubbed... URL: https://mail.music.vt.edu/mailman/private/sursound/attachments/20110710/b50ed4c0/attachment.html ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
Fons Adriaensen f...@linuxaudio.org 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
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 m...@hacklava.net 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
[Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
Folks, I've been reading up on the various proposals for 3D sound from a set of stereo speakers. The 3D Audio Alliance is working on such a system. Astound Surround is getting ready to market, Edward Choueiri is working on the same idea (see: http://www.studio360.org/2011/apr/29/adventures-3d-sound/ ) and there are others. I used to have a Carver pre-amp with Carver's Holography button but i could never get it to do much. Has anyone heard a truly 3D/360 surround effect from 2 speakers using this stuff? Ever heard a fly buzzing around your head, or an object in the back far-left of you or some such? Can any of this do as good of a job as Ambisonics? Is all of this just related to head transfer function mathematics? I've listened to some of the headphone applications of this like binaural and whatever these folks are doing here http://www.3d60.co.uk/index.php That demo on the 3D60 page sounds really cool, however nothing ever sounds like it's more than a foot from my head and nothing is ever right in front of me. Why can't they create an effect of something coming from a long distance away and getting closer and closer behind me? If it's all related to head transfer function you'd think you could create any sound your ears can hear. I'm looking at my audio system building options and I'd love to throw my money/space decor at 2 really good speakers and a good 2 channel pre-amp instead of 12 speakers in an ambisonic system with all the associated electronics. Any thoughts on all this 3D through 2 channel stuff? Thanks, -- Bearcat M. Şandor Jabber/xmpp/gtalk/email: bear...@feline-soul.net MSN: bearcatsan...@hotmail.com Yahoo: bearcatsandor AIM: bearcatmsandor ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
My personal opinion: a) 3D sound from 2 speakers Rubbish. Unless energy is arriving from the general direction of the supposed source, the best any system can do is present some psycho-acoustically confusing cues that attempt to fool the brain, but sadly (for the 2-channel snake-oil folk) the brain usually wins and tells you it is confused. b) 3D sound in headphones Better. With customized HRTFs and a virtualized 3rd order ambisonic system (18 speaker feeds - 3 rings of 6) or simply really good binaural recordings this can work very well, source material dependent. If you want 3D sound, then you are going to need considerably more channels than 2. - Neil On Jul 8, 2011, at 2:09 PM, Bearcat M. Şandor wrote: Folks, I've been reading up on the various proposals for 3D sound from a set of stereo speakers. The 3D Audio Alliance is working on such a system. Astound Surround is getting ready to market, Edward Choueiri is working on the same idea (see: http://www.studio360.org/2011/apr/29/adventures-3d-sound/ ) and there are others. I used to have a Carver pre-amp with Carver's Holography button but i could never get it to do much. Has anyone heard a truly 3D/360 surround effect from 2 speakers using this stuff? Ever heard a fly buzzing around your head, or an object in the back far-left of you or some such? Can any of this do as good of a job as Ambisonics? Is all of this just related to head transfer function mathematics? I've listened to some of the headphone applications of this like binaural and whatever these folks are doing here http://www.3d60.co.uk/index.php That demo on the 3D60 page sounds really cool, however nothing ever sounds like it's more than a foot from my head and nothing is ever right in front of me. Why can't they create an effect of something coming from a long distance away and getting closer and closer behind me? If it's all related to head transfer function you'd think you could create any sound your ears can hear. I'm looking at my audio system building options and I'd love to throw my money/space decor at 2 really good speakers and a good 2 channel pre-amp instead of 12 speakers in an ambisonic system with all the associated electronics. Any thoughts on all this 3D through 2 channel stuff? Thanks, -- Bearcat M. Şandor Jabber/xmpp/gtalk/email: bear...@feline-soul.net MSN: bearcatsan...@hotmail.com Yahoo: bearcatsandor AIM: bearcatmsandor ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
On Fri, Jul 08, 2011 at 02:19:15PM -0400, Neil Waterman wrote: My personal opinion: a) 3D sound from 2 speakers Rubbish. Unless energy is arriving from the general direction of the supposed source, the best any system can do is present some psycho-acoustically confusing cues that attempt to fool the brain, but sadly (for the 2-channel snake-oil folk) the brain usually wins and tells you it is confused. b) 3D sound in headphones Better. With customized HRTFs and a virtualized 3rd order ambisonic system (18 speaker feeds - 3 rings of 6) or simply really good binaural recordings this can work very well, source material dependent. If you want 3D sound, then you are going to need considerably more channels than 2. Agreed 100%. Ciao, -- FA ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
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. 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 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] the recent 2-channel 3D sound formats and their viability for actual 360 degree sound
On Fri, Jul 08, 2011 at 11:34:18PM +0100, dw wrote: 60 degrees seems excessive head movement for someone seated listening to speakers.. Why ? It's a natural thing to do if there is any significant sound from that direction. Why should being listening to speakers make any difference ? I like to forget I'm listening to speakers. And *if* I turn my head, for whatever reason, and the illusion collapses, I'm not impressed... I am fed up with the lack of *head tracking' being used as an excuse for poor sound localization performance. I remember so called 'researchers' 20 years ago recording the sound pressures in ear canals in an anechoic chamber, and then playing the recordings back via earphone or headphones in an anechoic chamber, and getting front to back discrimination little better than chance. The excuse was 'head tracking'. Which was probably correct. Anyway I'm not using lack of head tracking as an excuse. Any system using speakers clearly should not depend on it - it would reduce the system instantly to single-listener. Ciao, -- FA ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
