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Beyond stereo?


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Continuing what I think may be an interesting topic without further polluting the "What uncontroversial audible differences..." thread


Starting here

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  6 hours ago, Ralph Glasgal said:

Crosstalk is removed by using a barrier between two speakers directly in front of you

 

 

Yes, I was aware of that one and headphones.

 
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or now much more practically using the same two speakers with a processor that does the same thing as the barrier.  

 

Well, I have some doubts there, unless you mean reduced, or even perceptually removed (via reduction) to the equivalent of the barrier. perhaps with some head tracking and HRTF info.

 

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So now almost all movie dialog is not stereo but mono fed to a center speaker which you can localize to no matter where you are seated.

 

Understood, but again, for music, how much central "solidity" is needed to perceptually recreate an original soundfield?

I should admit to being a classical music attendee, but I enjoy jazz and other smaller/closer up ensembles as well.

 

 

 
 
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Take a look at http://analoghighend.blogspot.gr/2017/04/stereo-in-3d.html for a rave review of one XTC system.  If you go to www.ambiophonics.org you can click on other reviews.  There was another rave review for Amtra but it is in German.  The secret of modern XTC is that you must not use head tracking or HRTFs.  The RACE software outperforms the barrier since it works down to lower frequencies and it is really hard to make a barrier that truly isolates the speaker from the wrong ear.  But those that use a barrier are indeed devoted to it.

 

 

Ralph, that is a purely subjective review. I would need actual measured data or controlled listening data to support your contention the crosstalk is "removed"

 

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All imaging, central or not, benefits from psychoacoustic verisimilitude.  This means a coherent set of localization cues including those hall reflections from the sides, the rear, the front, and to a much lesser extent overhead (because these are mono).  You can compromise as non audiophiles do all the time, but you can do a lot better than traditional stereo quite easily while sticking to audiophile frequency response or resolution concerns. 

I didn't ask about all imaging. I asked specifically about the perceptual need for a "solid" central image as created by the crosstalk reduction you advocate, to replicate a real soundfield.

Such as those created by orchestras, or small, say jazz ensembles in smaller acoustic spaces.

TIA

 

 

EDIT: Adding some basics of what I'm really referring to:

http://www.aes.org/e-lib/browse.cfm?elib=9136 The description for the paper begins to explain the limitations of the stereo format and one possible MCH solution approach

http://www.linkwitzlab.com/Recording/acoustics-hearing.htm This explains the stereo is limited concept much further.

There is really no question MCH is a must for recreation of a real acoustic soundfield in spaces. But the  other reality is 98% of recorded music is stereo.

 

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A good idea for a topic.  Is the future beyond stereo multi-channel either in its current implementations or future varieties with even more channels?  Is it binaural with the proliferation of headphone use and personal sound which doesn't include people having a listening room?  Is it some simulation software that can do genuine 3D of one sort or another?

 

My fear is it will end up like AVR receivers that have a dozen or more format variants yet none are much more effective than others. 

 

Or perhaps basic stereo with a few software enhancements will continue to be the overwhelmingly dominant musical distribution format. 

 

I have seen several people say new formats that are successful were never about better sound quality.  They were always successful due to decreased cost and increased convenience.  Any genuine improvements in sound quality were incidental. I would say the one sure time when that was not true is the switchover to stereo from mono.  Stereo added some important new dimensions that were qualitative as well as quantitative.  The change in quality was perceived by music purchasers.  Once you heard even okay stereo then mono just won't do.  Hasn't been the case for adding additional channels. 

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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I can't help but wonder how much this is because we generally don't do enough about the room and that dealing with room issues with 4 or more speakers is even more complex than dealing with them with just two, not only on the listening end, but also in terms of what gets recorded and mixed and how and how that interacts with the room at the other end.  I would think that fewer channel create fewer variables, making them easier to control and compensate for. 

 

I can certainly hear hear significant differences in movies between cinema sound systems that are well set up and those that are not ( with most falling in the not category).  

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16 minutes ago, esldude said:

Once you heard even okay stereo then mono just won't do.  Hasn't been the case for adding additional channels. 

 

It depends on the material you are listening to. Avatar sounds far better with multi channel system than stereo playback.  To make a proper multi channel track, it is going to cost more and time consuming compared to stereo. 

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1 hour ago, AJ Soundfield said:

Continuing what I think may be an interesting topic without further polluting the "What uncontroversial audible differences..." thread


Starting here

 

 
 

 

Ralph, that is a purely subjective review. I would need actual measured data or controlled listening data to support your contention the crosstalk is "removed"

 

I didn't ask about all imaging. I asked specifically about the perceptual need for a "solid" central image as created by the crosstalk reduction you advocate, to replicate a real soundfield.

Such as those created by orchestras, or small, say jazz ensembles in smaller acoustic spaces.

TIA

 

 

EDIT: Adding some basics of what I'm really referring to:

http://www.aes.org/e-lib/browse.cfm?elib=9136 The description for the paper begins to explain the limitations of the stereo format and one possible MCH solution approach

http://www.linkwitzlab.com/Recording/acoustics-hearing.htm This explains the stereo is limited concept much further.

There is really no question MCH is a must for recreation of a real acoustic soundfield in spaces. But the  other reality is 98% of recorded music is stereo.

 

 

 

I think it will be useful if you go through the technical papers in Ralph's website as he already answered them. No one is saying stereo is perfect. Ambiophonics XTC teaches you how  to extract what's already in stereo.  In there you can find AES papers, blind tests, XTC filter comparison and etc.

 

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7 minutes ago, STC said:

 

 

I think it will be useful if you go through the technical papers in Ralph's website as he already answered them. No one is saying stereo is perfect. Ambiophonics XTC teaches you how  to extract what's already in stereo.  In there you can find AES papers, blind tests, XTC filter comparison and etc.

 

Brings to mind a question I had about the Aria3D demos.  Impressively 3D at times, but I rather doubted the position of the sound images with this process actually were the position of the sound source in the original recording. Is there some algorithm you could uncover to enlighten as to whether the 3D positions are related to actual positions of the original recording?

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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Some other articles which are relevant to the topic.

 

http://www.desena.org/multichannel/Ambisonics_2_Int_Symp_2010.pdf

 

Describes and compares two versions of Johnston and Lam's perceptual sound field methods and Ambisonics.

 

http://www2.ensc.sfu.ca/~ljilja/cnl/guests/cvetkovic.pdf

 

A powerpoint presentation of related material.  The video of that presentation is embedded below.

 

 

 

Finally a paper from earlier this year.

 

http://epubs.surrey.ac.uk/813317/13/hacihabiboglu_etal2017.pdf

 

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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Nowadays is possible to produce a printed 3D copy of a solid object, for example a human face, by performing a 3D scan.

 

Despite my relative ignorance in audio matters I suspect that for accurate reproduction of an instrument or singer one would need to record its sound in anechoic conditions with a large amount of mics distributed equally around it in a sphere-like grid, then feed each channel into the equivalently positioned driver of a sphere-like speaker.

This would of course have to rely on the acoustics of the listening room.

 

As I have mentioned previously, in my opinion immersive is an alternative to stereo with some advantages and probably some some disadvantages, but it is still not a realistic reproduction of the original.

"Science draws the wave, poetry fills it with water" Teixeira de Pascoaes

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3 minutes ago, semente said:

As I have mentioned previously, in my opinion immersive is an alternative to stereo with some advantages and probably some some disadvantages, but it is still not a realistic reproduction of the original.

 

Real live recording should sound real. Real sound is 3D. Immersive doesn't mean you are going to hear something different enveloping you with artificial feeling. The best demo I could think of is to record people having conversation like the video above and reproduce the same where you could localize accurately and the distinction between playback and real should disappear. For music that is recorded with real stereo, you will feel the same depth and width as the real event, although such recordings are getting rarer.

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41 minutes ago, STC said:

 

Real live recording should sound real. Real sound is 3D. Immersive doesn't mean you are going to hear something different enveloping you with artificial feeling. The best demo I could think of is to record people having conversation like the video above and reproduce the same where you could localize accurately and the distinction between playback and real should disappear. For music that is recorded with real stereo, you will feel the same depth and width as the real event, although such recordings are getting rarer.

 

But my point is that current 3D/ambio audio is still nothing like "real" sound.

 

Look at the dispersion pattern of a cello.

 

cello.thumb.png.59ea1c0990821c2662cc80178ddea307.png

How can you expect to mimic this behaviour without recording a sphere of sound and then reproduce it using something like this?

 

sphere.thumb.jpg.3d22786a375c70ca9b7a3d84739fe482.jpg

 

Your friend explained this in the other thread:

 

14 hours ago, Ralph Glasgal said:

Unfortunately human hearing expects that the direct sound and reflected sound be logical and physically possible.  Room reflections and reflectons from seats and heads in a concert hall are not all that different. But what stimulates them is.  In the concert hall the interarual level differences and the interaural time differences of early reflections correlate with the horizontal position of an instrument on the front stage. At home, with reflected sound coming from two fixed speakers these room cues are a form of acoustical nonsense.  There are other psychoacoustic issues as well such as long period reverb, diffuse tails, etc.

"Science draws the wave, poetry fills it with water" Teixeira de Pascoaes

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3 minutes ago, semente said:

 

But my point is that current 3D/ambio audio is not like "real" sound.

 

Look at the dispersion pattern of a cello.

 

cello.thumb.png.59ea1c0990821c2662cc80178ddea307.png

How can you expect to mimic this behaviour without recording a sphere of sound and then reproduce it using something like this?

 

sphere.thumb.jpg.3d22786a375c70ca9b7a3d84739fe482.jpg

 

 

 

 

What's about the dispersion patent of the cello?  Which of the sound radiation going to reach your ears?  All of them? Can you show me the radiation pattern of a loudspeakers?

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Just now, STC said:

 

What's about the dispersion patent of the cello?  Which of the sound radiation going to reach your ears?  All of them? Can you show me the radiation pattern of a loudspeakers?

 

The problem starts way before the loudspeakers, with the microphones.

I would start by rereading what Ralph wrote.


Your options are:

 

a) you listen in an anechoic room to a recording with ambient cues

 

b) you record in an anechoic room and use your room 

 

But this will still not sound really like a) you are transported to the original venue or b) the instruments are in your room because in a) for the reasons Ralph stated or b) because you'd need an omni mic array for recording and an omni speaker for playback.

"Science draws the wave, poetry fills it with water" Teixeira de Pascoaes

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3 minutes ago, semente said:

 

The problem starts way before the loudspeakers, with the microphones.

I would start by rereading what Ralph wrote.


Your options are:

 

a) you listen in an anechoic room to a recording with ambient cues

 

b) you record in an anechoic room and use your room 

 

But this will still not sound really like a) you are transported to the original venue or b) the instruments are in your room because in a) for the reasons Ralph stated or b) because you'd need an omni mic array for recording and an omni speaker for playback.

 

The most important thing to know about recordings is they do not contain all the ambiance of the venue. Ambiance comes from different directions. Thousands of them. You can have a very directional instrument or omnidirectional instrument but when recordings are made they only capture the direct sound and its ambiance. For other ambiance, they are usually recorded with rear microphones and played back with such speakers configuration. The trouble is you have not listened to sound with IR of concert hall from varies directions so it is impossible to explain with words.

 

It is more like trying to explain 3D movie experience to someone who never experienced a true 3D before. 

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6 minutes ago, STC said:

 

The most important thing to know about recordings is they do not contain all the ambiance of the venue. Ambiance comes from different directions. Thousands of them. You can have a very directional instrument or omnidirectional instrument but when recordings are made they only capture the direct sound and its ambiance. For other ambiance, they are usually recorded with rear microphones and played back with such speakers configuration. The trouble is you have not listened to sound with IR of concert hall from varies directions so it is impossible to explain with words.

 

It is more like trying to explain 3D movie experience to someone who never experienced a true 3D before. 

 

The amount of ambience depends on where you position the mics: close-mic'ing yields no ambience.

 

The same happens with your ears: first row means more direct sound, back row means a lot of ambience.

 

When you listen live, the ambience cues come from multiple directions - front, behind, sides above - but when you listen to a recording through the speakers those cues come from the speakers, whether you ambio-process or not.

What Ralph was saying is that if you add listening room reflections these will be "similar" to the reflections for both direct sound and ambience cues and that ruins the illusion: "human hearing expects that the direct sound and reflected sound be logical and physically possible".

"Science draws the wave, poetry fills it with water" Teixeira de Pascoaes

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Regarding the dispersion pattern of instruments, you can see from the image above that the cello produces sound in a different direction depending on the frequency it is playing; the balance between direct and reflected sound (ambience) will change as the melody develops.

 

If you add room reflections to the mix you will be making the speakers more obvious and the source of the sound and the reproduction of the ambience less credible/realistic.

"Science draws the wave, poetry fills it with water" Teixeira de Pascoaes

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1 hour ago, semente said:

 

The amount of ambience depends on where you position the mics: close-mic'ing yields no ambience.

 

The same happens with your ears: first row means more direct sound, back row means a lot of ambience.

 

When you listen live, the ambience cues come from multiple directions - front, behind, sides above - but when you listen to a recording through the speakers those cues come from the speakers, whether you ambio-process or not.

What Ralph was saying is that if you add listening room reflections these will be "similar" to the reflections for both direct sound and ambience cues and that ruins the illusion: "human hearing expects that the direct sound and reflected sound be logical and physically possible".

 

I won't comment of what Ralph said, although I understand his message.

 

In stereo recordings, all the ambiance would not be captured. In fact, I think they probably limit the amount of ambiance in the recordings. Ambiance should come from multi direction. If you try to capture the ambiance than the resultant sound would be muddy and congested like the videos I posted earlier. Although, the sound was congested the actual sound in the room is totally different. The next time, when you visit a concert hall, look around and see where they place the microphones. 

 

 

 

1 hour ago, semente said:

Regarding the dispersion pattern of instruments, you can see from the image above that the cello produces sound in a different direction depending on the frequency it is playing; the balance between direct and reflected sound (ambience) will change as the melody develops.

 

If you add room reflections to the mix you will be making the speakers more obvious and the source of the sound and the reproduction of the ambience less credible/realistic.

 

You are missing the important point there in the cello chart, i.e which of the radiating sound will reach you and which of other sound will reach you ears after bouncing of the surface. Then what will be ratio of the loudness of each reflected sound to the ears. And which of the reflection are important. 

 

To know more of the ambiance, you need to understand impulse response for the reproduction of ambiance. And there are few types of impulse response. You can make your own impulse response but if you go to pro sound website you can buy true stereo impulse response of various concert halls. For example, I use the 32 IR of St.Cecilia. These are true stereo IR where the location at 90 degrees at 23 degrees elevation of the left side hall is created in stereo. This IR will be used to reproduce the effect by way of convolution, of the sound bouncing of the wall from that direction. You have many IRs for right and left side, including ceiling reflection, back and front. 

 

Depending on your room reflection, this convoluted sound may be slightly different but since my room sound is practically zero, I get the extended reverb of without coloration because I am replacing my walls with the St.Cecilia. How accurate is this sound to St.Cecilia's? or is my room sound without these convoluted speakers will be more pleasant to listen? Only you can answer that after listening to such setup.

 

OTOH, you need not use these additional ambiance for all the recordings as some where meant to listen with very little ambiance. Paravotti would sound better with ambiance but a lullaby probably fares better without the ambiance.

 

I read somewhere that George Martin when he saw two speakers the first time for recordings " he asked why would they want to do that".

 

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10 hours ago, STC said:

 

 

I think it will be useful if you go through the technical papers in Ralph's website as he already answered them. 

 

No he has not. He provided a link to a subjective rave. If you can provide the links to the papers addressing the specific claim that the crosstalk has been removed, please do so, thanks.

This paper linked on the site mentions "attenuation", so again, perhaps "removed perceptually" might be the claim, but that is up to Ralph to clarify.

This graph has no units

FarinaCrosstalk5.JPG

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3 hours ago, semente said:

What Ralph was saying is that if you add listening room reflections these will be "similar" to the reflections for both direct sound and ambience cues and that ruins the illusion: "human hearing expects that the direct sound and reflected sound be logical and physically possible".

Johnstons paper and slides I linked in first post addresses this issue in much greater detail

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14 minutes ago, AJ Soundfield said:

No he has not. He provided a link to a subjective rave. If you can provide the links to the papers addressing the specific claim that the crosstalk has been removed, please do so, thanks.

This paper linked on the site mentions "attenuation", so again, perhaps "removed perceptually" might be the claim, but that is up to Ralph to clarify.

This graph has no units

FarinaCrosstalk5.JPG

 

I think there was another AES paper. But I understand your point. As far as I know crosstalk cancellation only applies to certain frequency range and around 20 or 30dB depending on the algorithm. So you could be right. 

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8 minutes ago, STC said:

As far as I know crosstalk cancellation only applies to certain frequency range and around 20 or 30dB depending on the algorithm. So you could be right. 

That might be enough, so I don't want to belabor a minor point.

Just noticed your link, interesting system you have there. Too many speakers for me, and I sell them! :D

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