3D audio report

Mark (Basspig) Weiss

Well-Known Member
Aug 3, 2010
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New Milford, CT
www.basspig.com
There's really nothing new here. I've been enjoying "3D" audio since 1982, when I set up my Carver C4000 for the first time. And since my theater remake in 2009, it's gotten even better (thanks to copious acoustic treatments). I've had the parent of a prodigal pianist performing with a regional symphony in here to hear a recording I made for an earlier client at that same concert hall and she was impressed with how the experience was so convincingly similar to what she experienced in that same hall a day earlier. Of course the recording was one that I made, using my proprietary mic array. Over the past year, I've had several professional classical musicians in here and have watched their jaws drop, every time I start the playback of a concert in a hall they're familiar with.
The 3D effect goes beyond realistic (with Classical recordings) to the enveloping, nearly 360° surround sensation with electronic music, like Joe Hisaishi's Kaze no tani no Nausicaä and The Weathering Continent soundtracks. Distance, both near and far, sounds to the right, left, and everywhere in between.. One engineer that didn't know what my speaker setup was swore I had 36 channels of sound back there!
I must give all the credit to Bob Carver. Sonic Holography is the one reason I tolerate the otherwise mediocre C4000 preamplifier.
 

metronimo

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Oct 10, 2010
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Thats interesting, I didn't know that he was involved in Ambiosonics. At any rate what he is doing now is classic cross-talk cancelling. I guess he has some new algorithms that work well.

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.
 

Gedlee

WBF Technical Expert
Jul 21, 2010
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POS (plain old stereo) can be so boring sometimes and I have always held that it is up to each individual to tailor their final sound as they see fit.
However, I do advocate that the system be as technically proficient as possible, then, add in your own flavor if you wish, in the amount you desire.

Tom

To me, the only way that this can happen is if the recording is boring. I, for one, am of the exact opposite opinion to yours. "Hi Fidelity" means just that - as close to the original as is possible. Anything else is playing "sound mixer/producer", a job that I have done before, but don't care to do for my favorite recordings. And basically, I only listen to my favorite recordings - the rest are, as you say, mostly boring, but remixing them doesn't seem to help.
 

RogerD

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May 23, 2010
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I have been working with a prof at Princeton on a 3D system that he is developing. He asked for a set of Nathans on loan so that he could test them. He got back with me last week and told me that the Nathans were the best speakers that he had tested among dozens of other brand-name Hi-End loudspeakers. He was rather surprised that, according to him, only my speakers performed as the manufacturer claimed. He seemed surprised by that! :)

The link to the report is here:

3D audio report

PS - he has purchased the set that he has.

"audiophiles would try to find what's wrong with it."

If it enhances the listening experience so much the better. I have been using a "black box" for years and it has maybe 10 dollars worth of parts in the circuit. While without hearing the professors system, I am unable to render a judgement. What they decribe is mostly what I experience daily.

If more audiophiles would show interest in improving what they hear in 3D technology (psychoacoustics) and get out of the box maybe this hobby would not be so expensive and be on the decline.
 

Gedlee

WBF Technical Expert
Jul 21, 2010
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I think that I was clear that "enhancements" are not really my thing. I don't see the future in binaural, for the reasons that I stated. To me, stereo recordings are what we have (a situation that is likely to prvail for a very long time), the producers make them as good as then can (some are better than others that's for sure) and I do not see me interfering with their art. Could this "system" be improved? Of course it can. Better monitoring loudspeakers is a good start, most of them are pretty bad - there are lots of improvements possible - but that's not my role. I "reproduce" the art, I don't create it or manipulate it.
 

Paul Spencer

Well-Known Member
Oct 4, 2010
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Well I heard a plain old stereo on the weekend and there was nothing plain about it. Wow. There were some tracks played that were mind blowing in their imaging. I still can't get over the fact that some of the sounds were hovering right in front of me. No sneaky black boxes, just a well set up system and some very interesting recordings.
 

Gedlee

WBF Technical Expert
Jul 21, 2010
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What the future will bring I do not know, but I heard tales of POS's eminent demis some decades back.

Its like Winston Churchhill once said upon overhearing a comment "They say the old man is going senile", to which he responded "They also say that he is going deaf!"
 

Ralph Glasgal

New Member
Those speakers seem to be only 7" apart.

That must be one crazy program.

I'd like to experience it myself one day.
I am a little bit late joining this forum so I apologize.
There are many ways now to experience Ambiophonics and I hope you will try one of them. In both the original Ambiophonic systems and the version used by Prof. Choueiri the need for speakers to be about one third the stereo speaker angle has been confirmed. There are very good psychoacoustic reasons for why this narrower spacing is optimum and I hope you will want to read all the material on the www.ambiophonics.org website to appreciate this. If you are are not technical take my word for it closer is better. I will try and add more details in answer to the other posts below. Note the ,org. Evgerything about Ambiophonics that I have anything to do with is in the public domain. Just as stereophonic technology is.

Ralph Glasgal
www.ambiophonics.org
 

Ralph Glasgal

New Member
The basic premise for crosstalk is that one ear hears information that is "meant" for the other ear, and hears it slightly delayed due to the longer path length to that ear from the speaker.

  • This "crosstalk" is what prevents more accurate imaging in both lateral location and depth perception, because the original sound is smeared by presenting the sound TWICE to each ear rather than once. End quote.
It gets worse than that. In reality, stereophonic hearing is a sonic illusion and like an optical illusion it is rather unstable or better said does not and can never deliver the physiological versimilitude that normal everyday binaural hearing delivers. Stereophonic hearing is not the same as binaural hearing. The use of the stereo loudspeaker triangle limits the interaural time delay to a maximum of about 220 microseconds compared to normal hearing of up to 700 microseconds and reduces the interaural level differences to the range of or or five dB compared to 15 to 20 dB in normal hearing or about 10 for concerts. The higher values are experienced when the bee buzzes around your head and it is these extreme values of ILD that Prof. Choueiri is attempting to deliver thus requiring speakers and software that is unusual. Standard Ambiophonics is more for music, games, movies, surround sound and thus is much more forgiving as to speaker types.

Addtionally concerning crosstalk, the human ear pinna are very sensitive to the direction from which the frequencies over 1000 Hz come from. In the stereo triangle this pinna angle is always 30 degrees and so it is wrong for the more critical central region where soloists are etc. But worse at these higher frequencies, there is a sequence of peaks and dips for central or even near side sources reaching each ear from each speaker that mimic pinna direction finding patterns aand these contradict the lower frequency level and time difference cues and thus tell the brain that the music is canned lacks depth, etc. What is more, for central souces the fact that both speakers reach both ears and that at bass frequencies there little loss across the head, there is a doubling of center energy compared to side sound in the bass region. Again, for a side sound, only one speaker is heard at both ears, for a mono or solo center two speakers sound out to both ears doubling the level. There is no way for a recording enginner to correct for this unless the center channel is mono as in spot mic'd.

Of course, like Black and White photography, one can regard stereo with all its quirks as an artform that is not expected to be realistic. What really happens is that color LPs and CDs are reproduced in black and white. All that localization data on the average recording is simply not reproduced or not reproduced with any accuracy.

One example. Let us say a sound from the extreme side is recorded with a time delay in the stereo recording of 700 microseconds. When this is played back via a speaker at 30 degrees the maximum delay is reduced to 220 microseconds and the image is no longer at the side but at the 30 degree point.

You don't have to take my word for all this. There are a lot of demo tracks you can play with on the Ambiophonic website. Some are preprocessed and you can just play them if you move two speakers to one third their normal spacing or listen to them via your laptop or PC speakers. In brief Ambiophonics or Ambio is simply a loudspeaker binaural 2D, 3D methodology that is tweakable just like the stereophonic or 5.1 methodology.
 

Ralph Glasgal

New Member
The basic premise for crosstalk is that one ear hears information that is "meant" for the other ear, and hears it slightly delayed due to the longer path length to that ear from the speaker.

The IsoMike recordings from Kimber take a different approach to reducing crosstalk. They use a special baffle between the microphones during the recording session, so that each microphone picks up mostly only the sound meant for that channel, and very little of the sound meant for the opposite channel. So, they attack the crosstalk problem at the recording end.

Lee
Unfortunately, even if you had complete separation of the recording mics, thus essentially having a left stage mono signal and a right stage mono signal, when you play this back the stereo loudspeaker crosstalk will still reduce the ITD and ILD to a third of its proper value and the comb filtering pattern will still confuse the pinna. The stage perspective will then be reduced to 60 degrees and the lack of depth, clarity, presence will prevail and the sense of being there will evaporate. Incidentally, the Ambiophone, a much more manageble mic structure, is pictured on the home page. Choueiri also uses something similar.

Ralph Glasgal
www.ambiophonics.org
 

RBFC

WBF Founding Member
Apr 20, 2010
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Ralph,

Thanks for joining the discussion! I appreciate you lending more clarity to the topic.

So, the stereo effect is also varied by frequency via pinnal sensitivity issues. Interesting!

Lee
 

Ralph Glasgal

New Member
I do not know what the premises of Edgar Choueiri's work are because I have not been able to find any publications but I wonder about your analysis of crosstalk cancellation. In the real world, a violinist standing in front of me but off 35deg to the right is heard the same way by both ears and that contributes to my ability to localize it precisely. Put a mic there and what comes out of the right speaker works the same way. The fact that both ears hear both speakers is what distinguishes stereo listening over speakers from stereo (not binaural) listening over headphones.

Kal

I try not to limit the term binaural to earphones. I use the term binaural to represent our normal hearing mechanism. One can attempt to mimic binaural hearing via loudspeakers or earphones, bone conduction, brain waves etc. Stereophonic hearing is something quite different in terms of physiology. But more significantly-

When you hear the violin in the concert hall one sound ray reaches each ear. Normally even if the violin is say at 30 degrees, both stereo channel mics will record direct sound from the violin and so since both ears at home are exposed to both speakers there will be four sound rays now instead of two. So the binuaral case and the stereo cases are not the same with one exception that is quite rare. If the speaker is at 30 degrees left and the violin is also at 30 degrees left and the right microphone has picked up no direct sound at all, then there will only be one ray at each ear and the normal binaural sense will work correctly. This is also the only case where the pinna direction finding angle is correct. Of course, the stage reflections and hall ambience will still be all wrong. There is no way the 60 degree stereo triangle can reproduce anything beyond the 30 degree point except by accident or phase error or some such happenstance. Same reason that 5.1 or the old quad cannot image at 90 degrees. (yeah, I know we all know of a case to the contrary)

There is nothing wrong with regarding the stereo loudspeaker triangle as an artform like black and white photography, but stereo reproduction is not the same as binaural (or you can also call it and do it via soundfield reproduction or wavefield synthesis). To futher confuse everybody, so-called stereo recordings (or better 2.0) are not inherently one or the other. Most standard 2.0 LPs or CDs play back really fantastically when played binaurally via loudspeakers (not earphones).

I invite Kal and all the readers of this list to come to New Jersey and hear for themselves what Ambiophonics or loudspeaker binaural can do for stereo material not to mention 5.1 stuff, games, operas, movies. Again, I have no financial interest in any of this.

Ralph Glasgal
www.ambiophonics.org
 

Ralph Glasgal

New Member
Kal,

What crosstalk cancellation attempts to do, in short, is turn the listening space into a giant set of binaural headphones. I remember playing with one of the early Carver Sonic Hologram Generators, which were a rudimentary example of the process I describe. When set up carefully, one could experience a full 180 degree soundfield that extended all the way to your sides, far beyond the speakers. Images had "reach out and touch it" realism. Tonal balance and richness of sound were unfortunately degraded somewhat, in the same manner that anaglyph 3D video flattens colors and brightness. However, the effect was startling at times.

Lee
Lee, you are right on. The Carver system was as you describe it. It was a remarkable achievement for its time. The basic problem with it was that is was not recursive. Same with the Polk or Fried speaker systems and some other crosstalk cancelling via speaker arrangements. The problem is that when you send a signal to cancel the crosstalk at the left ear which comes from the left speaker that that sound also reaches the right ear and now you need a signal at the right speaker to cancel this and so on. In RACE, (Recursive Ambiophonic Crosstalk Eliminator) the free program that I conceived, the crosstalk cancellation continues to inaudibility a process that takes a few milliseconds. The older oneshot approach is difficult to adjust and is unstable. But if you try RACE I think you will find it quite easy to use and not critical as to speaker type or placement. I think also, you will again experience that "reach out and touch it" or as I call it "you are there" realism.

Again, black and white photo enthusiasts may not take to color easily or at all, and similarly there is no reason why stereo loudspeaker enthusiasts should switch to loudspeaker binaural in any form.

Ralph Glasgal
www.ambiophonics.org
 

Ralph Glasgal

New Member
It works great when the recordings are done correctly. Problem is that it requires very specific recording techniques to work. There aren't many (any?) recordings like that, and I do not see the industry changing to doing so. It also begs the question - what is the role of a "recording" - to play back an "original space" or to creat a "new space" within the listeners space? Ambiophonics only really works for the former, it isn't really necessary for the later. I am not big on "recreating the impression of being in a music hall". Almost nothing that I listen has that as a goal. 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?

I usually try to avoid subjective discussions of artforms. But. While one can optimize ones microphone technique when one knows that the reproduction will be Ambiophonic rather than stereophonic, it turns out not to matter very much. I routinely play LPs and CDs made with coincident mics, or spaced omnis, all spots or just virtual reality things that never saw a microphone. Basically, to get the best effortless localization for anything, be it music, a movie, a game or any other sound you need to deliver the best value of ITD and ILD with the best pinna directionality you can. Ambiophonic reproduction methods do this better at a reasonable cost and complexity than any other commercially or readily available method at the moment. So Ambio definitely does not require specific recording techniques to work. That was a pleasant surprise when I started this research. It is amazing how much localization data is stored on LPs or CDs that is lost in the stereo loudspeaker reproduction process. LPs are truly amazing in this regard. In the early days they could not mix 24 spot microphones into the mix and then pot pan things into oblivion. So the ITD and ILD on most LPs is nicely pristine and produces a full wide stage with real prescence and depth. Some overeprocessed pop CDs may produce unexpected localization effects but whether this result (elevation or something behind you) is better or worse than the stereo localization is a matter of taste. Classical music CDs are normally to die for heard this way. The industry would not have to change its recording methods to accomodate Ambiophonics. But if they would monitor what they are doing using an Ambiodipole they could produce better stereo effects. Some recording engineers are already using microphones that resemble the Ambiophone. You can hear Ambiophone tracks by going to the Ambiophonic website.

Originally, John Atkinson termed Ambiophonics a means to achieve the Domestic Concerrt Hall and that is certainly one application. Ambiophonics does include provision for using concert hall impulse responses to convolve the front channels to generate hall ambience for any number of surround speakers you feel comfortable with and can afford. I have one system with 26 going here. (you can also use just two, but Ambio like stereo is nicely tweakable) You can either create a space you like for a studio recording or not. In stereo there is no choice and for classical recordings the hall ambience is all mushed up and comes from the front speakers which may be one reason why so few stereophiles listen to orchestral music even if it is not classical. Normall, Ambiophonics does transport the listener to the recording space. Or better said it presents the same perspective that the main microphone saw. First row center or whatever. If all you listen to is a vocal soloist with a guitar or small central combo then Ambio will not do a lot for the stage width but often a lot for depth. Eliminating the central low frequency boost and getting rid of the combing will provide a sense of purity and clarity, but again the stage size will likely not change much. Also a small combo has little ambience so using rear speakers as in Panambiophonics to get spaciousness or envelopement is not an issue. It think the migration of demos at audio shows from orchestral works in the early days to almost exclusivley Chesky type small vocal tracks now is due to the fact that large ensemble demos do not sell hi-end equipment.

Ralph Glasgal
www.ambiophonics.org
 

Ralph Glasgal

New Member
It turns out that good speakers don't hinder either approach - thank God! My speakers were deamed to be the best availablke for cross-talk cancelling, because of their high directivity. But their design was mostly done simply to deliver what is on the recording to the listener - to create in the listeners space what the producer had in mind. Sometimes this falls flat, especially when "the room effect" is desired and it is not on the recording. In this later case people will often rate the lower "performance" speaker which has wide directivity and hence adds room ambiance (as spatiousness) as "preferred" because it adds something that the listener deems to be valuable. From a manufacturers standpoint, however, this is a dead end simply because the type of music that is enhanced by a "room effect" is simply becoming obsolete. Like it or not, "classical" music is declining, has done so consistantly year after year, and I personally do not see this trend changing. I like classical music to some extent, but I am more than satisfied to restrict my listening to it live. I get enough that way. I don't find it nearly as appealing in a home environment and as such I never listen to it at home. I am perfectly content to live with "classical music live" and "studio music" at home. This is very satifying to me. I sympathize with people who seek "live classical music" at home, because this will be a very small sector of the market. A sector however that is idealy suited to ambiophonics. So if "being there" is what you seek, then ambiophonics is for you, but it will be outrageously expensive and have a very limited reperatoire that is not compatible with standard stereo. The main stream will stay with stereo.

Choueiri needs very special speakers to achieve very high values of acoustic crosstalk cancellation. Obviously unless you know the exact directional response of the speakers or can measure them easily, it is difficult to tell the software how to generate the crosstalk cancelling samples. There are also issues of reflections, crossovers, the matching of the speakers etc. But for most listening any speaker pair, if they are reasonably symmetrical and similar will work just fine. I use very tall electrostatics which behave like line sources and I often get 10 dB of cancellation which is more than the interaural level differences captured on most recordings. But even with laptop speakers the improvement is obvious. I have some five systems here, all with different speaker types and they work fine with RACE.

With the speakers close together room effects are much less troublesome. You can sit closer or even be in the nearfield in many cases. Also there may be some psychoacoustic effect that lessens the room effects compared to stereo. This makes sense since in a concert hall the reflections from nearby seats and people are hardly noticeable compared to the effect of having a full stage sounding front of you. Of course with full fledged 4.0 Ambiophonics or Pan ambiophonics with surround speakers the convolved ambience swamps the listening room reflections entirely. Crosstalk signals are on the order of a 100 microseconds. Room reflections on the order of 10s of milliseconds so I find the room has little effect on Ambiophonic localization. But I do like the TacT Ambiophonics box which includes speaker/room correction, remote control etc. but I am a fanatic and doing research it is necessary not to have loose ends.

You can convert to Ambiophonics for free using your present speakers and amplifiers or for $150 you can order an ambio4you.com processor box. The idea that Ambiophonics is costly is simply not true. If you want to add some of the surround options then yes the cost will be something like the cost of any 5.1 system except it will work. I never throw a speaker away. I simply make it another surround speaker source.

Yes, I am biased to classical music but classical music is not going to die. I hope Ambio reproduction can again make it more popular among audiophiles. A DVD of an opera reproduced Ambiophonically is an experience you should not miss. The same is true for a broadway musical or movies that have real rear stages, etc.

Ralph Glasgal
www.ambiophonics.org
 

Ralph Glasgal

New Member
Oh yes, ambiophonics only works at a single seating location. I think the better choice for playback of this type will be insert earphones. I am doing a large scale study of these for a client and I'll tell you right now, no loudspeaker even comes close to them for "perfection" of the impulse response. This makes them ideal for ambiophonics.
In stereo, if you move off the center line you usually localize to the nearest speaker and thus hear only one channel. In Ambiophonics, if you move off center, you still hear both channels. In stereo as you move closer to the speakers you get a hole in the middle. As you move back you get a narrow stage and then mono. In Ambiophonics when you move up you just get stereo and when you move back almost nothing happens. I often have some four or five people along the center line at once all watching the same DVD and if the rear Ambiopdipole is on they all hear a full 360 degree sound field with strong localization at the 90 degree points. Yes if they move to the side then they only hear front to rear. But this is still better than 5.1. Yes offside stereo is commonplace, but when one if offside in stereo one does not feel a great loss. In Ambiophonics the loss seems tragic. Indeed Ambiophonics is not for theaters, or parties or large groups. It is for listeners who really want to listen to something all the way through in a binaural way. Choueiri is working on a way to do this for a larger group. You can also use the IMAX approach of a separate speaker pair for each listener. I have done this and it does work. The interference between speakers is not all that bad.

Ralph Glasgal
www.ambiophonics.org
 

Kal Rubinson

Well-Known Member
May 4, 2010
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I try not to limit the term binaural to earphones. I use the term binaural to represent our normal hearing mechanism. One can attempt to mimic binaural hearing via loudspeakers or earphones, bone conduction, brain waves etc. Stereophonic hearing is something quite different in terms of physiology.
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
 

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