Beyond stereo?

[semente]

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.

[semente]

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.

 

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

 

 

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.

[semente]

Looks like someone is already working on this:

 

 

These Spherical Microphone Arrays Make Holographic Images of Sound 

http://gizmodo.com/these-spherical-microphone-arrays-make-holographic-imag-1741535712

[semente]

Here you can find an audio sample:

 

http://acoustics.org/2paaa4-does-it-sound-better-behind-miles-davis-back-what-would-it-sound-like-face-to-face-rushing-through-a-holographic-sound-image-of-the-trumpet-franz-zotter-matthias-frank/

 

 

And the researchers' website:

 

https://iaem.at/Members/projekte/sphericalarrays/compact-spherical-loudspeaker-arrays

[semente]

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.

[semente]

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".

[semente]

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.

[semente]

1 hour ago, STC said:

 

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. 

 

 

 

 

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".

 

 

i don't think you read Ralph's quote.

 

Up until recently I used to live in front of this concert hall; you can see the single pair of mics is hanging from the canopy:

 

 

This setup was used for broadcasting live concerts by many radios all over Europe, and some still continue to do so.

It sounds a bit like...live.

 

I agree that in stereo recordings, all the ambiance would not be captured.

And unfortunately many record companies close- and multi-mic and those recordings will have even less ambience.

But if the stereo recording did not capture all the ambience then there is no way to play it back with or without convolution/processing.

 

Pentatone multi-mic'ed Sa Chen in that same hall.

I listened to her play the week they made the recording and I can't really say that I like what they did in my two-channel setup.

Have a look at Pentatone's mic setup:

 

 

 

[semente]

6 hours ago, esldude said:

 

 

 

 

Thanks for the video.

[semente]

9 minutes ago, STC said:

 

I don't think anyone saying that. Almost all agree multi channel is the way. It is impossible to recreate realism with two channels only. 

 

Don't you mean soundfield realism, or source/space representation?

[semente]

4 hours ago, esldude said:

This sounded as if everything was full left or full right over headphones.   Only when she speaks is there much of a center.

 

 

 

I didn't add the video for sound assessment but just to illustrate mic positioning, although the SACD does sport both 2.0 and 5.1 versions.

Perhaps you can assess sound quality with this other video which I presume was recorded in the two days with audience but the sound may be from the Redbook layer:

 

 

[semente]

50 minutes ago, AJ Soundfield said:

That would not represent what 2 ears + head would hear, especially in a typical performance space.

I have yet to attend a music event in an anechoic chamber 

 

Perhaps you should reread  what I wrote.

If you wish to reproduce the radiation pattern of say a violin you'd have to do something similar to what I described.

You room would be the venue so you wouldn't be listening in an anechoic chamber.

 

This is a more accurate method of the rather simplistic AR live vs. reproduced demos. 

[semente]

9 hours ago, AJ Soundfield said:

That would work great if you listen to live violins in your room and wanted to listen to a recording of it without it being there.

What would that have to do with how most folks hear violins?

 

I guess you'll have to read my prior posts to find out.

 

But how is it that most folks listen to violins?

I guess they sit in a room and hear the sound coming out from the violin.

And conventional recordings and speakers cannot reproduce the sound of a violin accurately, the can only recreate a two dimensional illusion of what the violin sounded in the room it was playing in mixed with the reflections produced by your own room.

 

Please don't reply.

You win.

[semente]

7 hours ago, STC said:

 

Are you telling that if you play a real violin in concert hall and your room, it is going to sound the same ? That cannot be correct. 

 

That is not what I wrote.

 

Conventional recordings and speakers cannot reproduce the sound of a violin accurately, the can only recreate a two dimensional illusion of what the violin sounded in the room it was playing in mixed with the reflections produced by your own room.

 

What I mean is that you are looking for convincing holographic realism from a violin recording you won't get it unless you mic it all around and use an omni speaker AND you will have to give up on the original space.

[semente]

3 hours ago, STC said:

 

We agree that conventional recording may not capture al the sound of the violin. But what should matter is the recording should capture the sound that reaches our ears. THe sound that reaches our ears is only a fraction of the original sound.

 

It is wrong to say that speakers only reproduce 2 dimensional sound. A vocal recorded in mono should sound quite close to the original sound when played with a single speaker. That is 3D. Any sound reaching our ears from any source be it speakers or instruments are all behave the same way.

 

So if a violin played in two different venue going to sound different than even the recording that you mentioned in posts earlier also going to sound different. The problem is we are trying to recreate many instruments that were placed at various spots in actual event be confined to two or five or seven or 11 speakers. The front stage where an orchestra of 100 instruments are stil being reproduced by two or three speakers (LCR).  

 

So the recreate the realism, maybe your method of recording and reproduction is better but  it still limited to 2 or 3 speakers in the front to reproduce the multiple instruments. The proper way is to place the many instruments captured in the recording with the two speakers.  

 

The next stGe after addressing the former is recreate the venue. The so called room acoustics can be minimised or even replaced with creating our own by replacing our room wall with the impulse response of actual concert halls which is commercial available. Unfortunately, this requires more speakers for the venues acoustics.

 

1 hour ago, AJ Soundfield said:

It's helpful if you are aware of the field of psycho-acoustics and what has been found about perception of reflections, playing same instrument in different rooms to same people, etc, etc.

Try watching the Rumsey video I just linked, much of this is covered, or anything Dr Toole has written. All helpful here.

 

I am discussing this from the perspective of recreating in your listening room the radiation pattern or soundfield of an acoustic instrument.

Reproducing the recording of a violin playing in a music hall with 2 or even 5 channels will not do it.

 

My point is that a conventional recording will not be able to provide a realistic holographic soundfield of the violin.

 

But conventional recordings or photography or cinema can or may, with some degree of abstraction from the listener/viewer, provide a representation of the original musical event, sound, object, landscape, person...

 

And with this I return to my original comment where I mentioned that I find accurate sound reproduction more important than space reproduction in regards to music.

[semente]

44 minutes ago, STC said:

 

It can but not with stereo. But further discussion requires both of us to have experimented with all the different formats to know what's the difference. 

 

Listening is not helpful here.

I'll sketch a drawing latter today to better express my idea. 

[semente]

52 minutes ago, AJ Soundfield said:

So how do you explain this? http://www.onhifi.com/features/20010615.htm

It seems clear you're either not reading any of the research linked, or not understanding

See previous post.

There's no point in discussing further until I have made myself clear.

I am happy to stand for criticism then.  

[semente]

Just now, AJ Soundfield said:

Well there you have it

 

Yes. 

 

One of Ralph's posts a couple of days provides good information on what I mean.

[semente]

7 minutes ago, AJ Soundfield said:

So you didn't mean this

Because that does involve listening.

Perhaps you could make up your mind?

 

I meant realistic as in mimicking the radiation of a violin, which as shown previously in pics.

Yes a pair of mics does capture both direct and reflected sound but reproduction is then a) is subject to the radiation pattern of the speakers and b) interacts or is coloured/muddled by listening room reflections/interaction (anechoic listening could help). 

 

Perception studies are about listening and listening doesn't help here. 

[semente]

1 minute ago, AJ Soundfield said:

As long as the encoding captures the soundfield as 2 ears/head would hear said radiated polar field, that is irrelevant.

Once again, it appears you are not reading any of the literature.

A pair of mics is woefully inadequate. If you read, you would have seen Perceptual Soundfield Reconstruction techniques use 7 mics. The specific directional characteristics and reasons are explained.

Indeed one does want to capture both onset (aka direct) and indirect fields.

 

 I'm afraid you are quite lost here. That's what this thread is all about. If you want to know whether you have realistically encoded the violins radiated sound, listening tests are the final arbiter.

 

Sorry, I'm not following you.

99% of your interventions dismiss listening as subjective except with reference to Toole's research and when it suits you.

[semente]

4 minutes ago, STC said:

 

The ambiance if captured fully as heard by the ears would make the recording sound congested and muddy. In live performance the ambiance originates from multiple reflected surface. You shouldn't reproduce the ambiance ( even it is possible to record them) in the recording because all the different direction cues will now originate from the two speakers. Whatever ambiance that you hear in the recording is limited so that it would not  overly distort the sound when the room acoustics  add its own ambiance. 

 

 

 

That is what I have been saying. 

But it's not just limited by the recording speakers and speaker/room interaction are also a factor here.

More channels and processing improve spatial reproduction but in the end the method is still flawed.

[semente]

Imagine a drop in the first centre third of a rectangular glass box half-filled with water and a listener floating in the other third.

A first ripple will hit the listener and then many other ripples will ensue reflected by the walls - the ambience or spatial cues.

This is a simplified model of course because it's only working in a single horizontal plane.

 

If you try to reproduce this with say four corner speakers and a central one you will have to contend with the listening room added reflections, with the dispersion pattern of the loudspeakers and with the interaction between the speakers' soundfields.

[semente]

18 minutes ago, AJ Soundfield said:

Thanks for confirming you haven't read a single link. They are important to the discussion

 

Could you please provide me with the relevant links you are referring to?

You have posted quite a few in this and the other thread that has similar content.

[semente]

1 hour ago, Ralf11 said:

2 ears

2 mics

2 speakers

 

that ol' time religion is good enuff fer me

 

7 minutes ago, gmgraves said:

+1!

 

+another 1

[semente]

32 minutes ago, AJ Soundfield said:

That's George Clooney not me. Regardless, that's a long time to have not picked up anything regarding basic perception of soundwaves.

I'm not posting opinions. All those links are scientific facts, not opinions, such as you are posting.

If yours aren't, please post the files or links to your 2ch recordings that correctly capture the soundfield so that they can be rendered and perceptually reconstruct the original, TIA.

It is impossible to sample combined direct and diffuse with 2 mics that can then be rendered separately, because they are no longer separate. The leading edges of the planar waves cannot be simultaneously played back from the same speaker producing an unlocalizable diffuse field. If you don't understand any of this, no shame in saying so.

A bare minimum of 4 loudspeakers is required for envelopment as one would have in a live soundfield. Again, scientifically established fact, not fictional opinion.

 

All (2 channel or processed multi-channel) are approximations, which is why you very well wrote "perceptually reconstruct the original".

More mics/channels/speakers may* confer a more "realistic" soundfield but will also add complexity, problems, and cost.

 

The link about some reviewer describing JA wetting his pants is not a fact.

 

* - depending on who you ask...subjective