How to get depth in a stereo setup?

[mbhangui]

One of the more important properties of sound is that its speed is nearly independent of frequency. If this were not the case, and high-frequency sounds traveled faster, for example, then the farther you were from a band in a football stadium, the more the sound from the low-pitch instruments would lag behind the high-pitch ones. But the music from all instruments arrives in cadence independent of distance, and so all frequencies must travel at nearly the same speed.

14.1 Speed of Sound, Frequency, and Wavelength - Physics | OpenStax

Sound is a wave. More specifically, sound is defined to be a disturbance of matter that is transmitted from its source outward. A disturbance is anythin...

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See this question by @Analogous in the link https://www.hifivision.com/threads/hard-facts-from-a-hug-member.87931/post-988437 where he says

But I really haven’t heard any 2 channel system that convincingly showed layered depth or height.

Which is true for me. With effort in speaker placement, sound treatment, I have managed to get the center imaging, separating out artists, individual instruments, etc. But never the height and the depth. For height it can be logically explained because as long as you are recording with two microphones and the playback with two speakers only, you cannot get height because two speakers can give you left + right image. Just like you can't get the feeling of left and right with Mono recording or with a single speaker, for height you have to have minimum of 4 speakers with the MLP suspeneded between all the 4 speakers (two speakers left and right and two speakers top and bottom).

Now there are many who say that they hear depth. Let's say we have a singer who is singing and a piano is playing in the background. In a concert hall (non-amplified playback), since the piano is behind the singer, the sound from the piano will arrive at your ears later compared to the vocals from the singer (remember that the speed does not depend on the frequency). So it easy for our ears to know and feel that the piano is behind the singer. Now you record the event with two microphones, convert that into vinyl, cd whatever and play from your stereo system. Now both vocals and piano will play from the same speaker. So the sound from the singer and the piano will arrive at your ears exactly at the same time. So isn't it impossible for the person to determine of the singer is in front of the piano or behind the piano?

So the question is - Is it really possible to get realistic depth and height from a stereo recording played with two speakers? If possible, can some show how it is possible as per physics? Any article which shows the science. There are plenty available for how left and right works for stereo, but none that show how height and depth are possible with stereo.

NOTE: Even with headphones, the sound always appears to come from in between the head and never in front or behind. Even If i try to imagine depth, it sounds artificial and elusive.

 

[raghupb]

Mixing and mastering process.
I'll try to dig out a few articles on the tricks of the trade and post here.

Cheers,
Raghu

 

[balavignesh002]

A DSP with all active speakers can help on depth and imaging..

To experience the same effect of concert. Record each and every instrument separately and play the same on individual Mono speakers. Possibly place them on the same location the instruments were there.

 

[mbhangui]

To experience the same effect of concert. Record each and every instrument separately and play the same on individual Mono speakers. Possibly place them on the same location the instruments were there.

True. The physics also behind this sounds plausible and believable. What I'm trying to understand is if this is possible using just two speakers and if it is a very costly mirage that I'm chasing in a stereo setup. I'm very much happy with playing movies in a 7.1 system though. So the question I'm asking myself is if it is realistic to think stereo can give the same depth that movie playback give even with a modest avr?

 

[sandeepsasi]

In a concert hall (non-amplified playback), since the piano is behind the singer, the sound from the piano will arrive at your ears later compared to the vocals from the singer (remember that the speed does not depend on the frequency). So it easy for our ears to know and feel that the piano is behind the singer. Now you record the event with two microphones, convert that into vinyl, cd whatever and play from your stereo system. Now both vocals and piano will play from the same speaker. So the sound from the singer and the piano will arrive at your ears exactly at the same time. So isn't it impossible for the person to determine of the singer is in front of the piano or behind the piano?

Just an observation. If the sound from the singer arrives at our ears first, followed by the sound from the piano, isn't this also the case at the mics while recording, if they are placed in front of the singer?

With regards,
Sandeep Sasi

 

[Enkay78]

Hence I feel the Dolby Atmos for music might help in this aspect.

I may be wrong.....but I feel muti channel music in the future? (Yes I know the various logistics issue)

Maybe it's the long awaited....or not awaited convergence of HT and stereo music

So no separate system (hehe a taboo for many of us veterans)

 

[mbhangui]

Just an observation. If the sound from the singer arrives at our ears first, followed by the sound from the piano, isn't this also the case for the mics while recording, if they are placed in front of the singer?

Usually there are many mics used. There will be mic in front of the piano too. The mixer will tastefully mix this for a two channel setup (or dolby, atmos for multichannel). But the moment you convert into two channels, you have lost the height and depth info. only the relative amplitude between left and right remains and that when played from two speakers cannot magically get back the height and depth. That's my understanding. From whatever I have searched, I haven't found any scientific article showing how you get depth and height from a stereo setup. There will be plenty showing how stereo imaging works though.

EDIT:
Even in a live concert played and amplifed through speakers, I don't think you can know which instruments are behind and which in the front with your eyes closed.

Maybe it's the long awaited....or not awaited convergence of HT and stereo music

This is what I believe. For how long will the stereo brigade keep on saying a stereo setup is better? The big problem remains - most of the music is available in stereo. For old songs, it is impossible to get the original placement of the singers and instruments depth and height. And very few songs are available as multichannel.

 

[sandeepsasi]

Usually there are many mics used. There will be mic in front of the piano too. The mixer will tastefully mix this for a two channel setup (or dolby, atmos for multichannel). But the moment you convert into two channels, you have lost the height and depth info. only the relative amplitude between left and right remains and that when played from two speakers cannot magically get back the height and depth. That's my understanding. From whatever I have searched, I haven't found any scientific article showing how you get depth and height from a stereo setup. There will be plenty showing how stereo imaging works though.

I agree. If each source of sound is recorded using a separate pair of mics and mixed, then it is difficult to imagine how we get a sense of depth from that recording (based on my understanding of physics and these technologies). It thought it happens only in studio and not during live recordings.

However, if the live event is captured using a pair of mics placed in front of the stage, then I think the sense of depth will be captured as well.

With regards,
Sandeep Sasi

 

[balavignesh002]

True. The physics also behind this sounds plausible and believable. What I'm trying to understand is if this is possible using just two speakers and if it is a very costly mirage that I'm chasing in a stereo setup. I'm very much happy with playing movies in a 7.1 system though. So the question I'm asking myself is if it is realistic to think stereo can give the same depth that movie playback give even with a modest avr?

Most of the recording all instruments and vocals will have same TA, unless the the composer want to specifically do some changes to illustrate an effect.

On my experience imaging and staging is possible in stereo setup. I experience it daily in my cars, both have active setup.

In stereo home audio I get TA when I sit in between both speakers on same distance. Imaging and staging is right on the amp rack which is located 3 feet back of the speaker. I have kept 4 feet distance between speaker an rear wall.

Don't know what is hight you meen. If that's a vertical image it can be on array speakers. Have experienced once in Torvin demo with their array of mid and Tweeter on a tall speaker system which is again Stereo.

 

[mbhangui]

However, if the live event is captured using a pair of mics placed in front of the stage, then I think the sense of depth will be captured as well.

This is what I want to understand. For ear it happens through complex set of mechanisms. It uses reflection from nearby object and reflection from the ear's pinnae to determine the placement of the sound accurately. With mics, I'm not sure. Maybe some who has done PhD in sound can explain this. It is beyond my understanding.

Most of the recording all instruments and vocals will have same TA, unless the the composer want to specifically do some changes to illustrate an effect.

Pardon me. But what is TA acronym?

On my experience imaging and staging is possible in stereo setup. I experience it daily in my cars, both have active setup.

I do get imaging and staging in my setup. But it is in a two dimensional plane behind the speakers. The placement of the singers and instruments is accurate but always on a single plane behind the speakers.

Don't know what is hight you meen. If that's a vertical image it can be on array speakers. Have experienced once in Torvin demo with their array of mid and Tweeter on a tall speaker system which is again Stereo.

Let say a bird is chirping up in the ceiling. Will the sound from a stereo setup come from the ceiling. Let's say a helicopter is landing. Can a stereo setup convincingly show that the helicopter is moving vertically from top to bottom and not from behind towards you?

 

[jmascreen]

Try EMMA test disk for chrecking depth

 

[mbhangui]

Try EMMA test disk for chrecking depth

Is this the one https://emmanetshop.com/CD-and-Media/2020-high-resoltion-audio-files.html

 

[balavignesh002]

Pardon me. But what is TA acronym?

Time Alignment of speaker and listener

Let say a bird is chirping up in the ceiling. Will the sound from a stereo setup come from the ceiling. Let's say a helicopter is landing. Can a stereo setup convincingly show that the helicopter is moving vertically from top to bottom and not from behind towards you?

Stereo has its own limits.. the hights what you expect may not be posible to reproduce in stereo. Somthing similar possible if the mid and Tweeter is angled 45 degree up and inwards the listening position. That's what I have done in my car both mid and tweeter will be aiming the center roof of the car. But this is car, the over all stage is 2 feet hight and 4 feet length with 2 feet depth. I can feel the nearness and fairness of helecopter landing sound..

Have tried focal test CDs which has some recordings like these to demo. That can show she thing like this for example, foot steps from left top to right bottom.

 

[raghupb]

For @mbhangui and other folks tuned into this thread

Any recorded music (studio or live) will pass through the mixing and mastering phase.
Even in a studio, sometimes all parts of the music/song are not recorded at once.
This is simply because of scheduling conflicts of artists or whatever.
In elaborate recording sessions, sound engineers at the behest of the composer/producer will place multiple mikes for the same instrument or cluster of instruments. Then there are vocal and choral arrangements, etc, etc

Once the recording is done, the raw "tapes" or today the digital equivalents go off to the sound engineer's lab.
Here the producer/composer and the sound engineer apply their magic.

To start with you may want to read this to get familiar with terminology.
Then peruse here (simple primer), here (nice explanation), and here (very elaborate with pictures and sound examples).

Cheers,
Raghu

 

[mbhangui]

To start with you may want to read this to get familiar with terminology.
Then peruse here (simple primer), here (nice explanation), and here (very elaborate with pictures and sound examples).

Thank you for taking the time. I understood the terms about mixing. I also tried the samples (the third link you provided). Decreasing the sound level to make it sound further away. Increasing the sound level to make it more near you. I tried the samples and all I'm able to detect is the sound level but still the sound appears to come from the same two dimensional plane behind the speakers. Is it possible that my ears cannot make this out or are not getting fooled by sound level?. Maybe I will get there someday. I probably need to visit some FM in pune who say they have depth in their setup and hear it myself. The article also explains that the height thing is phychoacoustics (which is what I believed till now and believed this was some kind of interplay being done with the tweeter, mid-range driver placement). So depth is the thing I have to chase now.

@jmascreen shared the good bad ugly (masterpiece by Ennio Morricone). I'm getting a good sense of depth here

EDIT: Or is it because I was watching the video?

This particular link

 

[raghupb]

Thank you for taking the time. I understood the terms about mixing. I also tried the samples (the third link you provided). Decreasing the sound level to make it sound further away. Increasing the sound level to make it more near you. I tried the samples and all I'm able to detect is the sound level but still the sound appears to come from the same two dimensional plane behind the speakers. Is it possible that my ears cannot make this out or are not getting fooled by sound level?. Maybe I will get there someday. I probably need to visit some FM in pune who say they have depth in their setup and hear it myself. The article also explains that the height thing is phychoacoustics (which is what I believed till now and believed this was some kind of interplay being done with the tweeter, mid-range driver placement). So depth is the thing I have to chase now.

Happy to help a curious FM
Cheers,
Raghu

 

[arj]

Thank you for taking the time. I understood the terms about mixing. I also tried the samples (the third link you provided). Decreasing the sound level to make it sound further away. Increasing the sound level to make it more near you. I tried the samples and all I'm able to detect is the sound level but still the sound appears to come from the same two dimensional plane behind the speakers. Is it possible that my ears cannot make this out or are not getting fooled by sound level?. Maybe I will get there someday. I probably need to visit some FM in pune who say they have depth in their setup and hear it myself. The article also explains that the height thing is phychoacoustics (which is what I believed till now and believed this was some kind of interplay being done with the tweeter, mid-range driver placement). So depth is the thing I have to chase now.

Depth is of course mastered in and comes in only if you have speakers placed optimally ideally with 3-4 feet space behind the speaker and with the right toe in.

Try playing the below. you should find the trumpet playing far behind the singer in a 3D space.

 

[Bloom@83]

Depth is of course mastered in and comes in only if you have speakers placed optimally ideally with 3-4 feet space behind the speaker and with the right toe in.

Try playing the below. you should find the trumpet playing far behind the singer in a 3D space.

I tested this track the other day when this Cd was being discussed and yes , the trumpet appears clearly way behind the right
speaker , even though I have only 2 feet 7 inches clearance behind from the front baffle.

 

[mbhangui]

Depth is of course mastered in and comes in only if you have speakers placed optimally ideally with 3-4 feet space behind the speaker and with the right toe in.

Try playing the below. you should find the trumpet playing far behind the singer in a 3D space.

Played this multiple times on two different speakers at two different locations and two different amps. This is my experience
1. The vocals are very prominent and very focussed.
2. The sound of the trumpet extents beyond the right speaker. A good 3-4 feet beyond the right speaker.
3. Behind or front, this is where it gets fuzzy for me. If I imagine the speakers are behind the singer, I'm able to imagine the trumpet are behind the singer. If I imagine trumpet is playing on the right but in front of the singer, I feel that the trumpet is playing in front of the singer.

Could it be reflections playing havoc?
EDIT: I have this TV with solid glass as the front panel. Could it be this causing the issue

 

[raghupb]

You have quite a bi-polar imagination
Just kiddin'
Cheers,
Raghu