Strechneck,
Great if you have the paper. It may take some time to really understand what it is about. Walker proposition is not to control dispertion but to redirect the ER in order to create a kind of RFZ without to have overabsorption.
I linked it to you not for you to implement it, rather because this does explore the rendering of stereophony in room, the frequency range involved and a way to approach the issue.
And because this is from a reputable source this is backed up with measurements, explanation and definitions of subjective terms which help to understand why it is a somewhat debatable subject.
If you read it to the end you'll see that even for trained professional there may be some differences in the way this is accepted/expected/evaluated.
That is the reason why i asked you to define what you consider to be "depth" as we may be talking about different things.
About multicanal yes there is a version of the concept but it is a bit different that the stereo one. The stereo one is more interesting imho.
About distortion, as long as there is a deviation of the original signal this is distortion. Wheter or not this is relevant to you, me, the enjoyability of the experience or other things doesn t matter. Distortion is distortion.
Some are detrimental some less ( we can accept relatively high level of 2nd harmonic distortion without complaining... it can even be seen as something enjoyable, ask any owner of triode tube amplifier.
).
Psychoacoustical effect is a deviation from original signal.
Great if you have the paper. It may take some time to really understand what it is about. Walker proposition is not to control dispertion but to redirect the ER in order to create a kind of RFZ without to have overabsorption.
I linked it to you not for you to implement it, rather because this does explore the rendering of stereophony in room, the frequency range involved and a way to approach the issue.
And because this is from a reputable source this is backed up with measurements, explanation and definitions of subjective terms which help to understand why it is a somewhat debatable subject.
If you read it to the end you'll see that even for trained professional there may be some differences in the way this is accepted/expected/evaluated.
That is the reason why i asked you to define what you consider to be "depth" as we may be talking about different things.
About multicanal yes there is a version of the concept but it is a bit different that the stereo one. The stereo one is more interesting imho.
About distortion, as long as there is a deviation of the original signal this is distortion. Wheter or not this is relevant to you, me, the enjoyability of the experience or other things doesn t matter. Distortion is distortion.
Some are detrimental some less ( we can accept relatively high level of 2nd harmonic distortion without complaining... it can even be seen as something enjoyable, ask any owner of triode tube amplifier.
).Psychoacoustical effect is a deviation from original signal.
Scott, i don t think Linkwitz is wrong or that you or Juhazi are mistaking things or following wrong path. This is just different approach to the same issue.
I do not agree about Linkwitz observation about inwalls and have a different point of view of his own approach but i don t think there is a right or wrong way to approach the problem.
Different side of a coin i will say.
I do not agree about Linkwitz observation about inwalls and have a different point of view of his own approach but i don t think there is a right or wrong way to approach the problem.
Different side of a coin i will say.
Good thread with good info, thanks guys! 
The subject of depth in the audio fascinates me and I have some 30 years of experience with trying to understand it. So I'll throw in my views and experience.
Depth is definitely in the recording - or not. Even mono recordings. Every system I've heard that had believable depth illustrated this. Some recordings are very deep, some stay right between the speakers, some are a mix of depths. Some speakers will place the image out in front. I wonder if the out in front is an artifact of the system, or in the recording.
The common thing I've observed about systems that had real depth is that the wall behind the speaker was far away, or non existent. I've never heard depth from any type of speakers that were close to the wall behind them. Yes, I've heard the speaker owners talk about "fantastic depth" but I didn't hear it. Some examples of situations where the depth illusion has worked for me are; in my lava cave where the wall was 30 ft behind the speakers. In a high end showroom where the Focal speakers were a good 15 feet from the wall, in a small theater where there was distance and heavy velour drapes behind the speakers, or in John's garage with the back of the speakers facing the driveway.
The garage door trick is one I've posted before. I visited my buddy John and went out to his garage to listen to some speakers, including the Manzanita.The garage door was open and Harry James was playing trumpet out in the driveway, about 20 feet beyond the speakers. Push a button and down comes the garage door. Now Harry and his trumpet are pushed right against the door. Depth gone, or at least limited to the barrier behind the speakers. Open the door and the image shifted back out to the driveway.
That's consistently been my experience with depth in audio playback. If the wall behind the speakers is close, I hear it and the illusion is ruined. The depth goes no farther back (for me) than the barrier behind the speaker. Perhaps very diffused reflections from behind the speaker could sustain the illusion, I've had some experience with that, but not enough.
As to the original question about in-wall, I don't know. Though I've heard a few in-wall systems, I can't remember anything about depth. Curious to know more!
The subject of depth in the audio fascinates me and I have some 30 years of experience with trying to understand it. So I'll throw in my views and experience.
Depth is definitely in the recording - or not. Even mono recordings. Every system I've heard that had believable depth illustrated this. Some recordings are very deep, some stay right between the speakers, some are a mix of depths. Some speakers will place the image out in front. I wonder if the out in front is an artifact of the system, or in the recording.
The common thing I've observed about systems that had real depth is that the wall behind the speaker was far away, or non existent. I've never heard depth from any type of speakers that were close to the wall behind them. Yes, I've heard the speaker owners talk about "fantastic depth" but I didn't hear it. Some examples of situations where the depth illusion has worked for me are; in my lava cave where the wall was 30 ft behind the speakers. In a high end showroom where the Focal speakers were a good 15 feet from the wall, in a small theater where there was distance and heavy velour drapes behind the speakers, or in John's garage with the back of the speakers facing the driveway.
The garage door trick is one I've posted before. I visited my buddy John and went out to his garage to listen to some speakers, including the Manzanita.The garage door was open and Harry James was playing trumpet out in the driveway, about 20 feet beyond the speakers. Push a button and down comes the garage door. Now Harry and his trumpet are pushed right against the door. Depth gone, or at least limited to the barrier behind the speakers. Open the door and the image shifted back out to the driveway.
That's consistently been my experience with depth in audio playback. If the wall behind the speakers is close, I hear it and the illusion is ruined. The depth goes no farther back (for me) than the barrier behind the speaker. Perhaps very diffused reflections from behind the speaker could sustain the illusion, I've had some experience with that, but not enough.
As to the original question about in-wall, I don't know. Though I've heard a few in-wall systems, I can't remember anything about depth. Curious to know more!
I'm not sure what you mean? Psychoacoustics is about perception and interpretation
Relying on psychoacoustical effect.
For example if you play with a parametric eq around 100hz you may give a very different rendering of your speakers this is an effect.
Or another example, if you use a 'subharmonic synthesizer' which accentuate the first harmonic of the lowest note of a signal you can give the feeling that there is lowbass presents in a 3" woofer which can not reproduce them.
For example if you play with a parametric eq around 100hz you may give a very different rendering of your speakers this is an effect.
Or another example, if you use a 'subharmonic synthesizer' which accentuate the first harmonic of the lowest note of a signal you can give the feeling that there is lowbass presents in a 3" woofer which can not reproduce them.
I'd like to turn the discussion around a little bit. Let's say that I'm a recording engineer and I desire to make a stereo recording that has 2 layers of depth: one forward (between the speakers) and one far behind the speakers. What do I do? Do I have to make some assumptions about the playback system (speakers and room)?
Bbutterfield: there is many ways to skin a cat!
The more obvious one if you use a single pair of microphone (oldschool technique) is to place the couple far away from the source you want far away and the source you want upfront close to your couple of mic.
This is oversimplified because you ll have to choose the type of couple you want to use, which will define if you rely on stereo effect from intensity difference (x/y, or m/s), stereo from spacement (a/b) or a mix of both ( ortf, nos, jenkins disc,....), and the aesthetic you want...
If you do it 'new school' multiple mic technique, you send the signal to one or two reverb effect and play with the parameters... if you want up front use only the ER in the reverb mix and cut the tail parameter ( this will give you the feeling to be in a room but let space for other signal), for the one far away you ll have to adjust ER time and direct sound balance and you let the tail in). You can cut a bit the high freq with an eq on the far away source.
Likewise oversimplified but you get the idea...
The more obvious one if you use a single pair of microphone (oldschool technique) is to place the couple far away from the source you want far away and the source you want upfront close to your couple of mic.
This is oversimplified because you ll have to choose the type of couple you want to use, which will define if you rely on stereo effect from intensity difference (x/y, or m/s), stereo from spacement (a/b) or a mix of both ( ortf, nos, jenkins disc,....), and the aesthetic you want...
If you do it 'new school' multiple mic technique, you send the signal to one or two reverb effect and play with the parameters... if you want up front use only the ER in the reverb mix and cut the tail parameter ( this will give you the feeling to be in a room but let space for other signal), for the one far away you ll have to adjust ER time and direct sound balance and you let the tail in). You can cut a bit the high freq with an eq on the far away source.
Likewise oversimplified but you get the idea...
The lava cave!
Pano you probably experienced what G.Massenburg did in the studio c of Blackbird Nashville:
Blackbird Studio C, Nashville TN - Designed by George Massenburg | Acoustique | Pinterest | Blackbird studios, Studio and Nashville
This shouldnt work theorically... too much diffusion is theoricaly not good. But what an impressive room ! ...and afaik not many complaint from works done there.
Pano you probably experienced what G.Massenburg did in the studio c of Blackbird Nashville:
Blackbird Studio C, Nashville TN - Designed by George Massenburg | Acoustique | Pinterest | Blackbird studios, Studio and Nashville
This shouldnt work theorically... too much diffusion is theoricaly not good. But what an impressive room ! ...and afaik not many complaint from works done there.
Having tested this many times I would say Yes, to some extent.
If I am in a space where the system has profound depth I'll close my eyes. Consistently the image becomes shallower. It doesn't flatten completely, but it does lose depth. On the flip side, if I close my eyes listening to a system that has no depth - no depth is added. (sometimes just a little)
My conclusion was that the illusion is mostly auditory, but visual clues enhance it. My cave was a good example of that, the end of the cave didn't move but recordings had different depth, even within the same recording.
Fully agree. 90% of our sense treatment is dedicated to view 10% for other sense.
I ve had same experience in PlusXXX studio A in Paris. Very large width room (largest Ams/Neve 88r console i ve seen probably 72 or 84 strips) not very deep but rear wall fully covered with diffusors. You had the feeling the room was much much bigger than what is was (already a big room anyway). Really disturbing for me.
About depth an stereo, i once visited a loudspeaker maker. We discussed about acoustic and CID approach while listening to a relatively big mtm (2×12" + 1 horn loaded cd , xed at 1,2khz bi amplified). I was saying that most of the stereo was from 1khz and up freq range ( results from the bbc paper). The guy grinned and told me we had to try that so he cut the amplifier driving the woofers. Outcome from me:" bla, bla,bla, you see this works bla bla bla..." him, "ok let s try the other way around" and... my jaw dropped! There is so much information about stereo in the low end content!
Pretty enlightning.
Since i ve read some interview of one of Lexicon engineer ( THE REVERB BRAND) saying that there is many clues about stereophony in the low end.
Go figure...
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I agree with Krivium on this.
My experience on playback was the the reverb of the recorded space is what gave it depth. Any recording of a large space had depth, even mono recordings. The up front sound is from close mics. A good example is some of the Sinatra recording with orchestra. The orchestra is behind, Frank is up front. Some recording I've have are distinctly layered, but I don't know what are the clues that make them sound that way. The VR guys probably know.
The old album "Belefonte at Carnegie Hall" has some astounding depth effects. On the last track "Matilda" there is a call and response between Belefonte and the singers on stage, then the orchestra, then the audience - going all the way to the very top tier balcony. Don't know how it was recorded, but on a system with real depth the sound goes back, and back as the response comes from people farther away in the audience. The delay all the way to the back is funny, and Belefonte comments on it. But the depth is startling to hear on a recordings. That's a reference track for me.
Thanks, I've seen those photos before, but didn't know where it was.
Very much like my lava cave, but the wood diffusion has more depth than the lava walls did. The advantage of the cave was NO parallel surfaces anywhere, and a chaotic surface. It was an acoustical dead space, called Hypoechoic. It did not have sense of envelopment, its only acoustic fault.
Attachments
Yes, for sure. I hear a lot of room clues in the 400 Hz range, too. I suspect that people hear differently. I localize bass rather well, some people don't. Locating a 1K tone or beep in a room is devilishly difficult!
How do you think you'd perceive a mono recording that included a conversation between two people, one of which was talking normally and was mixed loudly, and the other person yelling, but mixed quietly? Let's say both were actually close mic'd and had equal (and minimal) amounts of reverb.
Alternatively (but perhaps equivalently), how do you think you'd perceive a conversation between two people recorded with a single mic in an anechoic chamber, where one person was close to the mic, and the other person was farther from the mic (and thus quieter)?
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You ll perceive it as someone yelling mixed quietly and the other talking normally!
edit: it happend sometimes in tunes whith backing vocals /lead singers I think you could here that kind of things in Hardcore(metal) recording a lot. Right know the only example i can think of is evanescence "bring me to life" during the refrain/bridge at 2:06 until 3:07 for example when the boy answer to Amy lee. She was a pretty cute girl by the way ...i had forgotten....
To be serious, this is what happend when you listen to broadcast (radio or tv). But this is related to compression issues ( you know when someone whisper at the same level than when he is yelling).
Compression is another subject by itself. But in some way it could be related to depth too: to much compression and you ve got a dynamically 'flat' signal, no more difference between quiet and loud signals : no more depth everything sound the same. Can be experienced each time you listen to radio station dedicated to recent/ modern pop music.
Don t know if that answer what you was thinking about.
edit: it happend sometimes in tunes whith backing vocals /lead singers I think you could here that kind of things in Hardcore(metal) recording a lot. Right know the only example i can think of is evanescence "bring me to life" during the refrain/bridge at 2:06 until 3:07 for example when the boy answer to Amy lee. She was a pretty cute girl by the way ...i had forgotten....
To be serious, this is what happend when you listen to broadcast (radio or tv). But this is related to compression issues ( you know when someone whisper at the same level than when he is yelling).
Compression is another subject by itself. But in some way it could be related to depth too: to much compression and you ve got a dynamically 'flat' signal, no more difference between quiet and loud signals : no more depth everything sound the same. Can be experienced each time you listen to radio station dedicated to recent/ modern pop music.
Don t know if that answer what you was thinking about.
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About the anechoic chamber you ll have the feeling the volume change between the two and a subjective lack of high in the farther one ( because air does 'absorb' high end content).
One more interesting (psychoacoustic) propertie of our hearing is the "cocktail effect".
Imagine you are in a bar. You sit at a table with an omni mic recording the overall ambiance. You listen to a discussion between some of your neighbour sitting 2meters away. You can focus on the discussion, no problem in spite of average noise. Playback the recording you made... you could not hear the discussion in the average noise!
Cocktail effect!
This is somewhat used at mix when you want to introduce a new instrument to an already heavy mix: you just push the new instrument volume for the first note played then you back it down just after that: you draw attention to it briefly, your brain know it is here then. You can make other parts disappearing too at the same time... works quite well.
It is used in radio playlist too when the "on air" processing does kill all dynamic: you make the start of a new song to clip for maybe one or 2ms, this give our brain a clue of track change within a continous 6db dynamic range signal ( white or pink noise anyone?! ).
But don t make me go off topic, this is a bad habit i naturally have and original subject is interesting.
One more interesting (psychoacoustic) propertie of our hearing is the "cocktail effect".
Imagine you are in a bar. You sit at a table with an omni mic recording the overall ambiance. You listen to a discussion between some of your neighbour sitting 2meters away. You can focus on the discussion, no problem in spite of average noise. Playback the recording you made... you could not hear the discussion in the average noise!
Cocktail effect!
This is somewhat used at mix when you want to introduce a new instrument to an already heavy mix: you just push the new instrument volume for the first note played then you back it down just after that: you draw attention to it briefly, your brain know it is here then. You can make other parts disappearing too at the same time... works quite well.
It is used in radio playlist too when the "on air" processing does kill all dynamic: you make the start of a new song to clip for maybe one or 2ms, this give our brain a clue of track change within a continous 6db dynamic range signal ( white or pink noise anyone?!
).But don t make me go off topic, this is a bad habit i naturally have and original subject is interesting.
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Bbutterfield: there is many ways to skin a cat!
The more obvious one if you use a single pair of microphone (oldschool technique) is to place the couple far away from the source you want far away and the source you want upfront close to your couple of mic.
...
If you do it 'new school' multiple mic technique, you send the signal to one or two reverb effect and play with the parameters... if you want up front use only the ER in the reverb mix and cut the tail parameter ( this will give you the feeling to be in a room but let space for other signal), for the one far away you ll have to adjust ER time and direct sound balance and you let the tail in). You can cut a bit the high freq with an eq on the far away source.
Likewise oversimplified but you get the idea...
Thanks for sharing your thoughts. I can't quite tell if you're addressing creating a (vague) sense of depth, or creating an illusion of depth that's believable during playback. I'm skeptical that you could accomplish the latter with what you described as a "new school" approach.
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