3D audio report

[Ralph Glasgal]

His BACCH x-talk cancellation IR file used to be distributed on ambiophonics.org; I don't know why it was removed. I've been using it with my home system for several months, and I prefer this listening setup to conventional stereo for any kind of musical material (including live classical...). A physical x-talk cancellation barrier is even better, and I intend to build a retractable one; I wonder if speaker directivity is an important factor in this case since the physical barrier would be doing most of the job.

There is now so much material, pictures, programs and products on the Ambiophonic website that the server people wanted to up our storage rate. So I had to lighten the load and since there is a much updated version of Bacch now running at Princeton I deleted this as well as some papers that were not really relevant.

If you are an audiophile that can hear the difference in cables and prefer LPs to digital media then the barrier is the way to go. A nice thick sound aborbing wall standing on edge where you can sit at the end of it and listen to two speakers that are directly along it at the far end is an audiophiles dream. Perfect frequency response, excellent crosstalk cancellation excepot in the low bass, no noise, no digital, 100% analog, no cables, tames the room reflections, etc. If the speaker radiates frontwards and doesn't spray sound up to the ceiling or a lot to the sides then the barrier will take care of the rest. You can even use two different types of speakers on each side of the wall and they don't have to be balanced or at the same distance (within reason) from the end where you sit. The first time I made and tried out such a barrier was the day I started to work on Ambiophonic systems that could duplicate a barrier in software or a component. The effect was magical. Of course one cannot do surround sound with the barrier unless you put another one close behind you which is very difficult. Echobusters once made such a barrier that folded up so you could store it easily. I put a small flat TV screen at the end of the barrier and that was fun for awhile. Obviously only a perfectionist fanatic would still use a barrier now that the software is perfected and free and even the ambio components are affordable.

Ralph Glasgal
www.ambiophonics.org

 

[Ralph Glasgal]

I didn't invent or define the term but binaural audio reproduction, is used to describe a system in which two separate channels are recorded with the microphones spaced a head-space aside or placed into the ear canals of a dummy head. Those two channels are fed, separately, by headphones to the the two ears with no intervention of room acoustics. Again, I do not know what "stereophonic hearing" is in terms of sensory physiology but stereophonic reproduction is, well, all of us know what that is.

This is not meant as a comment or criticism of Ambiophonics which, in the one demonstration I heard, was quite impressive but let's not confuse the terminology by re-defining accepted terms. Yes, we do hear binaurally but we are talking about music reproduction. Kal

It will be a miracle if anybody reads all this. Perhaps I can make the point clearer with an analogy to the visual 3D sense. In normal seeing the eye can sense depth essentially only if there is a difference in what reaches each eye due to their spacing. Let us call this binavision. But we have all seen printed optical illusions (Escher, etc.) where we see depth despite looking at a flat photograph. We can call this visual mechanism stereolusion. The point is that there are two essentially unrelated ways to feed depth cues to the brain, but nobody would say that stereolusion is the equal of or as 3D as binavision. Okay, to quibble, the brain stays the same but it can be stimulated in two quite different ways one more effective than the other. Stereolusion is an invented aritfice not really encountered in nature.

Likewise there are two ways at least that humans can localize sound. They are perhaps a bit more related than my visual examples but they are distinctly different. The phenomena that allows most humans to hear something in front of them when the sound sources are far to the side but equal in level is a sonic illusion that has been given the name stereophony or stereophonic hearing. It seems to have been really invented by Blumlein although it is hard to believe that this phenomena had never been observed earlier. But he got a patent so it must have seemed novel at the time. That this method of hearing is not quite what nature intended is evidenced by the fact that if you turn so that one ear is at a right angle to the plane of both sources you will almost certainly hear one source or the other and slight movements will shift this. This is why the quad speaker arrangement never could image at the 90 degree sides. Also if you move forward and back across the center line of the speakers you will hear a decided change in the frequency response of the sound. Try this with white or pink noise. This is the stereo combfiltering. No matter what microphone is used, if the speakers are placed as in the normal triangle the reproduction is stereophonic. The recording is just 2.0 even if made with a dummy head or the KFM-6 or the Soundfield, etc. Blumlein did call his invention binaural sound but in the 1950s the name was changed to stereophonic sound.

Normal hearing has to have a name and most of the AES-Bell Labs literature talks about monaural and binaural hearing mechanisms as well as mono and stereo. So one can have loudspeaker stereo and loudspeaker binaural. Since nobody would say that earphone listening uses the stereophonic sonic illusion described above, it was called binaural and I think this is reasonable since the earphones can deliver a normal ITD and ILD to the ear canals if the recording is properly done and we do not require a new brain function to explain how earphones produce localization. Earphones are physiologically binaural even if no dummy head microphone is involved. Of course earphones do not work as well as speakers in a binaural sense because it is almost impossible to not interfere with the pinna functions. Also head motions confuse the brain since the image moves with it and earphones usually produce internalization. I appreciate there are now fixes for all these things and I have no problem with headphones being one of the binaural reproduction methods. Loudspeaker binaural, in theory does not have any of these problems but getting rid of the crosstalk has stymied most researchers. Finally, limiting the use of the word Binaural it earphones and dummy head recordings may be commonplace but I think this is a mistake.

There are other recording and reproduction systems that produce a normal binaural soundfield for listeners via speakers. One is called Ambisonics and the othe Wavefield Synthesis. Again neither one relies on the fluke whereby one localizes the stereo way. Because these methods are truly binaural they can produce a full 3D sound field including height. But neither is useful in home sound reproduction or can play exisiting 2.0 recordings.

Unless you have heard Ambiophonics in the last year or so it is unlikely that you have heard it fully perfected. You can check with some of the RAVE guys who have now been here twice or Audiophile Society Members.

Ralph Glasgal

 

[Kal Rubinson]

It will be a miracle if anybody reads all this. Perhaps I can make the point clearer with an analogy to the visual 3D sense. In normal seeing the eye can sense depth essentially only if there is a difference in what reaches each eye due to their spacing. Let us call this binavision. But we have all seen printed optical illusions (Escher, etc.) where we see depth despite looking at a flat photograph. We can call this visual mechanism stereolusion. The point is that there are two essentially unrelated ways to feed depth cues to the brain, but nobody would say that stereolusion is the equal of or as 3D as binavision. Okay, to quibble, the brain stays the same but it can be stimulated in two quite different ways one more effective than the other. Stereolusion is an invented aritfice not really encountered in nature.

Yup. Visual mechanisms are common; it is the stimuli that are manipulated.

Likewise there are two ways at least that humans can localize sound. They are perhaps a bit more related than my visual examples but they are distinctly different. The phenomena that allows most humans to hear something in front of them when the sound sources are far to the side but equal in level is a sonic illusion that has been given the name stereophony or stereophonic hearing. It seems to have been really invented by Blumlein although it is hard to believe that this phenomena had never been observed earlier. But he got a patent so it must have seemed novel at the time. That this method of hearing is not quite what nature intended is evidenced by the fact that if you turn so that one ear is at a right angle to the plane of both sources you will almost certainly hear one source or the other and slight movements will shift this. This is why the quad speaker arrangement never could image at the 90 degree sides. Also if you move forward and back across the center line of the speakers you will hear a decided change in the frequency response of the sound. Try this with white or pink noise. This is the stereo combfiltering. No matter what microphone is used, if the speakers are placed as in the normal triangle the reproduction is stereophonic. The recording is just 2.0 even if made with a dummy head or the KFM-6 or the Soundfield, etc. Blumlein did call his invention binaural sound but in the 1950s the name was changed to stereophonic sound.

Well, I certainly hope someone else is reading this as I am familiar with these issues.

Normal hearing has to have a name and most of the AES-Bell Labs literature talks about monaural and binaural hearing mechanisms as well as mono and stereo. So one can have loudspeaker stereo and loudspeaker binaural. Since nobody would say that earphone listening uses the stereophonic sonic illusion described above, it was called binaural and I think this is reasonable since the earphones can deliver a normal ITD and ILD to the ear canals if the recording is properly done and we do not require a new brain function to explain how earphones produce localization. Earphones are physiologically binaural even if no dummy head microphone is involved. Of course earphones do not work as well as speakers in a binaural sense because it is almost impossible to not interfere with the pinna functions. Also head motions confuse the brain since the image moves with it and earphones usually produce internalization. I appreciate there are now fixes for all these things and I have no problem with headphones being one of the binaural reproduction methods. Loudspeaker binaural, in theory does not have any of these problems but getting rid of the crosstalk has stymied most researchers. Finally, limiting the use of the word Binaural it earphones and dummy head recordings may be commonplace but I think this is a mistake.

It may be a mistake but it is common and accepted terminology for a form of recording/reproduction. Adding the modifier to say "loudspeaker binaural" is another matter. BTW, I discuss some of these issues in my column in the November issue in the context of a review of the Smyth Realiser.

Kal

 

[metronimo]

There is now so much material, pictures, programs and products on the Ambiophonic website that the server people wanted to up our storage rate. So I had to lighten the load and since there is a much updated version of Bacch now running at Princeton I deleted this as well as some papers that were not really relevant.

Is that "much updated version of Bacch" available for download?
The project web site is in construction, with no Bacch file :
http://www.princeton.edu/3D3A/

 

[Ralph Glasgal]

Is that "much updated version of Bacch" available for download?
The project web site is in construction, with no Bacch file :
http://www.princeton.edu/3D3A/

They tell me this is the wrong forum so I will make this short. I hope to provide a link, but likely will not be able to support the new programs directly since they do not load into the same convolvers, etc. Why not try some of the other VST, Transcoders, and AudioMulch things in the meantime. They are newer than the Bacch filters have extra adjusstments, and most people like them.

Ralph

 

[metronimo]

They tell me this is the wrong forum so I will make this short. I hope to provide a link, but likely will not be able to support the new programs directly since they do not load into the same convolvers, etc. Why not try some of the other VST, Transcoders, and AudioMulch things in the meantime. They are newer than the Bacch filters have extra adjusstments, and most people like them.

Ralph

I tried a few options for ambiophonics (free and commercial) and I much prefer the BACCH IR file with a good convolver (JConv) on Linux. I would really like to try the newer BACCH... In the meanwhile I will build a physical barrier and get speakers with better directivity.

 

[Ralph Glasgal]

Hi Ralph,

I have an old image concepts ir2200 that is fun to use on occasion. Tell me more about that $150 box. Like how does it connect up. Direct to the analog outputs of the cd player or what?

Thanks,

Tom

Yes. It can go between a CD/LP player/tuner/Ipod/etc. and preamplifier or between a preamplifier and an amplifier or just like the old tape recorder loops. You can all contact me directly at glasgal@ambiophonics.org since this I am told is not the appropriate forum. Ralph

 

[WinstonMarlow]

I googled "Princeton University's Edgar Choueiri 3D Audio," it pulls up links connecting him with Ambiophonics.

"The development of ambiophonics is the work of several researchers and companies including Ralph Glasgal, founder of the Ambiophonic Institute; Dr. Angelo Farina, University of Parma; Robin Miller, Filmaker Technology; Waves Audio; Dr. Roger West, Soundlab; Dr. Radomir Bozovic, TacT Audio; and Prof. Edgar Choueiri, Princeton University."

http://www.ambiophonics.org/Bio.html

IMO, without a list of the "dozens of other brand-name Hi-End loudspeakers" he tested; Prof.Choueiri's statement doesn't mean very much.

Prof. Choueiri's 3D3A Lab website (http://www.princeton.edu/3D3A) at Princeton University has been recently updated with material that answers some of the questions in this thread. First, there is now a list of the six loudspeakers whose directivity were measured in his lab. Among the six, the GedLee Nathan was said to give the highest directivity. Indeed, this seems to be the case from looking at the measurement plots posted at http://www.princeton.edu/3D3A/Directivity.html

There is also more detailed description of Prof. Choueiri's research and work on 3D audio, along with a link to a detailed technical paper. The question about the difference between what he is doing and Ambiophonics, which was discussed on this thread, is answered (see Question 17 on the Q&A list at http://www.princeton.edu/3D3A/PureStereo/Pure_Stereo.html). It seems to be a very different approach than Ambiophonics.

I hope this helps.

 

[c1ferrari]

Virtually all studio creations use stereo as part of the art, not a window to the art. A lot of the disagreements that come up in audio stem from this basic point of view - what is it that you expect from your stereo?

Well conveyed

 

[Gedlee]

Stereo sort of sucks as it tries to bring the performance to you, and not you to the performance. I've said it a million times. We need a change.

Tom

I think this is precisely what I was talking about, because, to me, stereo does a very good job of "bringing the performance to me", but not at "taking you there". The exact opposite of your opinion. There is no way to resolve this kind of difference in expectation. I think that this is why many of these "new" techniques do not succeed, because they are based on the same premise that you describe, but not everyone excepts this premise. I don't and I don't see a need "for a change".

 

[Kal Rubinson]

I think this is precisely what I was talking about, because, to me, stereo does a very good job of "bringing the performance to me", but not at "taking you there". The exact opposite of your opinion. There is no way to resolve this kind of difference in expectation. I think that this is why many of these "new" techniques do not succeed, because they are based on the same premise that you describe, but not everyone excepts this premise. I don't and I don't see a need "for a change".

It may depend on what you listen to. I have enjoyed, and continue to enjoy, many solo and small group recordings in stereo since it is possible for them to simulate a performance in my room. However, I mostly listen to classical music with ensembles of more than a handful of players and cannot accept the illusion of more performers than can possibly fit in my listening room, even with my eyes closed. Multichannel removes that constraint by replacing my room's acoustics, to a huge extent, by those of the performance space.

Kal

 

[Ron Party]

I'm with Kal on this point. Whenever I listen to 2 channel music reproduction, even on the finest gear-speakers-room, as good as it may sound, I am always left wanting. At a minimum, 3 speakers across the front are required, particularly if the music has a singer center stage.

 

[RBFC]

I'm with Kal on this point. Whenever I listen to 2 channel music reproduction, even on the finest gear-speakers-room, as good as it may sound, I am always left wanting.

I've said many times that multichannel done right could save classical music from history's trash pile. Multichannel is actually a selling plus when I shop for newly recorded classical (orchestral) works.

At a minimum, 3 speakers across the front are required, particularly if the music has a singer center stage.

This Groove Note SACD sampler:

http://www.amazon.com/True-Audiophi...NRCS/ref=sr_1_1?ie=UTF8&qid=1289692596&sr=1-1

Has stereo and multichannel versions of several songs. On the multichannel versions, the singer's voice is preserved a bit better (IMO) with the active center channel vs. the phantom image. Track 12 with Eden Atwood, Blame It On My Youth, is an incredible solo voice/acoustic bass duet piece for over half its length, and is superb! Compare the vocal focus between the stereo and multichannel tracks on that one! There's a good version of Stormy Monday guitar blues and cuts with Jacintha, etc.

Lee

 

[Gedlee]

Kal

I can whole-heartedly agree, this is my experince as well. Fortunately, for me at least, classical is not my preference and small ensembles fit the bill for my daily fare. And, again, fortunately for me, the buying public is nearly 97% on my end of the scale.

I think that I said this earlier, but I'll repeat it just the same. Stereo cannot compete with live, large ensemble music in a good auditorium. That's why I only listen to this kind of music that way. I go to live orchestral performances several times a year. I almost never go see a small ensemble live, or, God forbid, live reinforced performances. If you think about it for a moment, you will see that this makes perfect sense.

By the way, I haven't been to a movie in a commercial theater in more than five years. I am certain that I will die before I do that again. I see, on average, about five films a week.

Is this all making some sense?

 

[Gedlee]

I've said many times that multichannel done right could save classical music from history's trash pile.

Lee

Lee

I'll take that bet. More than just multi-channel is required. This is why so many orchestras are moving away from a purely "classical" palet.

 

[metronimo]

I don't and I don't see a need "for a change".

Stereo is one technique; since its invention there have been many variations in the art of recording and reproduction, and that's why we can listen to old and new recordings in various conditions. The "job" of an audiophile is to listen to many musical styles and "sound systems" in order to develop his critical sense and share his experience with other audiophiles. You have expressed your preference for studio-produced pop music over live classical music recordings; between the two there are worlds of differences, and that's what makes music so interesting.

I like my stereo experience with cross-talk cancellation, no matter how the recording was produced. When listening to old jazz recordings from the 60's, even if a clarinet is "wrongfully" jumping out from the extreme right, I like it better than with a normal stereo configuration where the instrument is directly coming out of the right speaker at 30 degrees. When listening to a newly-recorded string quartet, cross-talk cancellation is marvelous, even if the recording was produced for normal stereo; the listening experience with cross-talk cancellation is just so much better than with normal stereo, and so much more enjoyable than with heaphones or earphones.

I believe that conventional stereo sounds better with a pair of Nathans, and I believe that this "Pure Stereo"(tm) is the ultimate experience. But I don't and probably won't have access to these patented and licensed technologies. All I have is a very small room with minimal acoustic treament, a pair of small DIY fullrange speakers driven by a $30 T-amp, and a old P4 computer running a BACCH convolver, using an old BACCH file that used to be available for free.

I had my hi-fi epiphany 10 months ago when I first tried a physical barrier for cross-talk cancellation. This ultra-simple technology is available, not patented and probably unbeatable. It works with any sound system, old, new, cheap or expensive. Even if it is too low-tech and silly looking to be considered marketable, trying it should be mandatory for any audiophile. If there's no need for a change, there's good enough reasons to change.

 

[Steve williams]

I had my hi-fi epiphany 10 months ago when I first tried a physical barrier for cross-talk cancellation. This ultra-simple technology is available, not patented and probably unbeatable. It works with any sound system, old, new, cheap or expensive. Even if it is too low-tech and silly looking to be considered marketable, trying it should be mandatory for any audiophile. If there's no need for a change, there's good enough reasons to change.

very interesting. Can you describe how this is done

 

[Kal Rubinson]

Gedlee-

It makes perfect sense. My interests would not be served by such, as you see. As for the 97%, that may be an accurate assessment but, since it is probably includes all music/equipment buyers, I'd guess that 90% of them don't really listen seriously at all.

Kal

 

[RBFC]

very interesting. Can you describe how this is done

You erect a physical barrier or wall that extends down the midline between your speakers and stops just in front of your face. So, sound from one speaker has no path to reach the opposite side ear. Some folks have used those movable wall panels like those used for office cubicles.

Lee

 

[RBFC]

Lee

I'll take that bet. More than just multi-channel is required. This is why so many orchestras are moving away from a purely "classical" palet.

Earl,

It's not a bet, but there's a reason that it's mostly classical music that's being issued on multichannel SACDs. Folks see little reason to re-buy another rendition of an old warhorse in the same old stereo presentation. Also, the replication of the hall ambience is far more believable through surround reproduction on well-done discs.

There's other reasons for the "hibernation" of classical music, but that's beyond the scope of this discussion.

Lee