Blue or red pill?

[STC]

9 minutes ago, mansr said:

We need to differentiate between stereophonic recording and stereophonic playback. One can have the latter without the former.

 

I don’t think so. A mono recording is still a mono even if you use stereo mode.  The stereo is the same sound with different level and phase over two speakers.  One mono on the left and another mono on the right can be argued as mono.

[pkane2001]

7 minutes ago, STC said:

 

I don’t think so. A mono recording is still a mono even if you use stereo mode.  The stereo is the same sound with different level and phase over two speakers.  One mono on the left and another mono on the right can be argued as mono.

 

Don't know why this is even an argument. I have a simple EQ unit that will generate variable phase and level differences between left and right channel, even when fed mono input. Isn't this an example of mono recording to stereo playback?

 

[adamdea]

38 minutes ago, mansr said:

If I drop a small object on the floor, I generally try to listen for where it went so as to more easily find it. Quite often, it works.

....And there are the keys you find by whistling and listening to the beep. 

 

But you are being tendentious (if perhaps playfully so): what you do when you drop an object is to listen for it so as to be able to have a starting point in finding it. Then you look in the general direction where you think it is from the sound. How often do you try to locate something purely from the sound of it? That is (as you well know) what I meant by "from sound alone".

 

This is different from

• using sound as one of many sources of information to locate something
• the sense of location of a sound object you get when you are able to draw on lots of pieces of information. 

 

Trying to use sound alone is really tricky as anyone who has dropped their keys in the pitch black will attest.

 

[adamdea]

19 minutes ago, esldude said:

I don't think you understand what I'm saying. Posting from a phone.  I'll be more clear and deliberate in a later reply.

OK. I interested to find out because at the moment I just can;t see the inference from the effects of an artificial pinna to the effects of comb filtering.

[adamdea]

35 minutes ago, pkane2001 said:

 

I've not been following the discussion about depth perception in recorded audio, as I generally agree there's usually very little 'real' depth information in most recordings, especially multi-mic, multi-track ones.

 

But, there is certainly something to the depth cues that might help locate a source of sound, while not precisely, but relative to other sources in the same recording. Call it reverb, echo, reflections, comb filters, combined with volume changes, these can all add to the sense of depth on a well made recording (or artificially manufactured depth on recordings where this is done through digital manipulation).

 

As I posted yesterday, I could clearly hear relative depth of instruments on a simple binaural recording when played back through loudspeakers. Some of the recordings I tried placed sound in front of my speakers, and this is the first time I've heard that effect. Again, these do not give a precise position, but relative to other sounds it makes for a nicely layered soundstage -- something we audiophiles love to hear.

 

Of course, I've also heard depth in other recordings, some seem to place sounds well beyond the speakers, others right at the speakers. An example of a manufactured sound stage depth I find amazing is on the Dire Straits On the Night live recording, f.i. The stage is placed so far behind my speakers, that it appears to come from the next room. As I understand it, that's just a post-processing trick, but makes for an impressive listening experience.

 

As far as measuring depth from a recording, I don't think that's possible with complex music, but it should be doable from some test signals, such as a recorded short pulse or a sweep.

Sure. You definitely can get some sense of depth in some recordings. You can for example make an "offstage" noise a bit quieter, have a bit of hf roll off and a bit more reverb: ca y est.

Some of the links I have posted have information about actual comparison of purely auditory distance estimation compared with real distance. Sound alone is not that precise even in real life, let alone stereo. But you can also get a sense of depth from other things not in the recording such as an image of the performers. Now that can give you precise layering.

[pkane2001]

14 minutes ago, adamdea said:

....And there are the keys you find by whistling and listening to the beep. 

 

But you are being tendentious (if perhaps playfully so): what you do when you drop an object is to listen for it so as to be able to have a starting point in finding it. Then you look in the general direction where you think it is from the sound. How often do you try to locate something purely from the sound of it? That is (as you well know) what I meant by "from sound alone".

 

This is different from

• using sound as one of many sources of information to locate something
• the sense of location of a sound object you get when you are able to draw on lots of pieces of information. 

 

Trying to use sound alone is really tricky as anyone who has dropped their keys in the pitch black will attest.

 

 

Trying to understand your argument. Is it that the actual sound produced by an object, in the absence of any reflections, reverb, etc. does not carry positional information? I think most will agree with this, no?

 

But that's not what happens in the real world, and a good recording should be able to capture more than just the primary sound. While the secondary audio cues are not precise, they do provide some direction and depth information that can be interpreted by our ear/brain combination in the absence of any other sensory input. Do you disagree?

[adamdea]

24 minutes ago, pkane2001 said:

 

Don't know why this is even an argument. I have a simple EQ unit that will generate variable phase and level differences between left and right channel, even when fed mono input. Isn't this an example of mono recording to stereo playback?

 

I find this whole thing a bit baffling because I take it as read that most of the recordings I have are a mixture of mics, some of them pairs some of them singles. I don;t know how many of my orchestral and opera recordings are purist and have avoided the use of any spot mics. If you have a coincident pair as the main feed and a few omnis for ambience what do you call that?

[adamdea]

3 minutes ago, pkane2001 said:

 

Trying to understand your argument. Is it that the actual sound produced by an object, in the absence of any reflections, reverb, etc. does not carry positional information? I think most will agree with this, no?

 

But that's not what happens in the real world, and a good recording should be able to capture more than just the primary sound. While the secondary audio cues are not precise, they do provide some direction and depth information that can be interpreted by our ear/brain combination in the absence of any other sensory input. Do you disagree?

This has already gone on for pages. If you want to understand my argument you'll have to read the posts.  Boradly there is reasonably accruate left right in a stereo recording, a bit of ambiguous depth and no height

 

You can get a bit of a sense of depth from the sound alone, but the sense you do get can be a lot more than that because of things other than the actual sound. 

 

[pkane2001]

3 minutes ago, adamdea said:

This has already gone on for pages. If you want to understand my argument you'll have to read the posts.  Boradly there is reasonably accruate left right in a stereo recording, a bit of ambiguous depth and no height

 

You can get a bit of a sense of depth from the sound alone, but the sense you do get can be a lot more than that because of things other than the actual sound. 

 

 

That's what I got from reading the thread, and I agree with this.

[Spacehound]

4 minutes ago, adamdea said:

fThis has already gone on for pages. If you want to understand my argument you'll have to read the posts.  Boradly there is reasonably accruate left right in a stereo recording, a bit of ambiguous depth and no height

 

You can get a bit of a sense of depth from the sound alone, but the sense you do get can be a lot more than that because of things other than the actual sound. 

 

I've got a recording  of 'Carlingord Loch' by a  Scottish bagpipe band.

 

The 'solo' piper at the start gradually walks forward, joins the others and only then do they  all start up.

 

I reckon  its done by turning the volume and the 'high end' down on the 'console'  and gradually increasing both. There's  not enough room where they did it for him to walk the distance it sounds like.

[adamdea]

22 minutes ago, pkane2001 said:

 

Trying to understand your argument. Is it that the actual sound produced by an object, in the absence of any reflections, reverb, etc. does not carry positional information? I think most will agree with this, no?

 

But that's not what happens in the real world, and a good recording should be able to capture more than just the primary sound. While the secondary audio cues are not precise, they do provide some direction and depth information that can be interpreted by our ear/brain combination in the absence of any other sensory input. Do you disagree?

Sorry if my previous post does  not seem helpful.

What I think is quite close to your second para but (and it's a big but) I think one has to be careful to distinguish between aspects of a recording which might engender a sense of depth and "capturing" (ie encoding) actual information that eg two instruments are 5ft apart in distance from the listener by either (eg)

• there being  two instruments one 5 feet nearer than the other where the recording is recorded naturally; or
• there being a bloke in the control room who says let's make the two instruments 5 feet apart by turning a dial

The difference between vaguely engendering a sense of depth and encoding it is very important if one want to start drawing conclusions. I think you can vaguely engender it (the tenor is singing from some way off, or "we are listening from a distance") but not precisely encode it in stereo by either of the means I have outlined.

 

The listener may then, as a result of various mechanisms, experience the sound in a way which makes it seem that depth information has been precisely encoded. The problem is that people who experience it in that way take a lot of persuading that that does not mean it has been encoded. However if you follow my earlier posts you should be able to see why this is the case. I think this is roughly Mansr's position but he has better things to do with his time than spell it out. That said if he did, he would probably do so much better then I

[adamdea]

7 minutes ago, Spacehound said:

I've got a recording  of 'Carlingord Loch' by a  Scottish bagpipe band.

 

The 'solo' piper at the start gradually walks forward, joins the others and only then do they  all start up.

 

I reckon  its done by turning the volume and the 'high end' down on the 'console'  and gradually increasing both. There's  not enough room where they did it for him to walk the distance it sounds like.

Is there more reverb on the bagpipes at the beginning, gradually reducing?

[mansr]

1 hour ago, STC said:

I don’t think so. A mono recording is still a mono even if you use stereo mode.  The stereo is the same sound with different level and phase over two speakers.  One mono on the left and another mono on the right can be argued as mono.

That's a rather degenerate case. I was thinking of a synthetic two-channel signal created by mixing multiple tracks, as is common practice, played back over two speakers. Do you not agree that this should be considered stereophonic playback, even though the recording was anything but?

[STC]

11 minutes ago, mansr said:

That's a rather degenerate case. I was thinking of a synthetic two-channel signal created by mixing multiple tracks, as is common practice, played back over two speakers. Do you not agree that this should be considered stereophonic playback, even though the recording was anything but?

 

It all started because I said the same thing.  

[mansr]

9 minutes ago, STC said:

It all started because I said the same thing.  

George has his own definitions, apparently. Better not to waste time arguing about them.

[adamdea]

2 hours ago, pkane2001 said:

 

That's what I got from reading the thread, and I agree with this.

I sometimes feel that whenever two people manage to agree on something on a forum they should get a small round of applause. So pour yourself a well-earned drink. 

[esldude]

4 hours ago, adamdea said:

OK. I interested to find out because at the moment I just can;t see the inference from the effects of an artificial pinna to the effects of comb filtering.

 

Height is sensed by comb filtering effects of the pinna primarily causing comb filtering between 6 khz and 11 khz.  

 

My supposition was that some microphone techniques have a vertical displacement of a distance that would create comb filtering in the combined sound wave in that frequency range.  So that might explain why some recordings could have some sense of height upon playback though likely not being accurate in terms of height and reality of the recorded instruments. 

 

I confirmed by quick and dirty experiment that vertical displacement can cause that comb filtering to result.  However those recordings though having a combing type response did not create any height when I listened to them.  Creating simple delays or FR EQ to create that kind of response also failed to create any perception of height upon playback.  

 

Upon considering the experiment where volunteers wore molds that altered the shape of their pinna I reconsidered.  These people still had pinna and would have had comb filtering in the right range, but the subtle changes were enough to destroy their ability to accurately hear height and some other directionality.  It took several weeks of adaptation before their acuity with the new pinna shape returned to normal.  

 

My conclusion from the experiment is that the combing patterns are not simple with real ear shapes.  Very slightly altering them destroys height perception.  There probably are multiple spectral points involved instead of a simple mostly single predominant filter.  So such a single simple filter point created by microphone displacement vertically is likely too simple by far to ever accidentally create height cues for the listener of recordings.  Therefore I deem it unlikely any stereo recordings have genuine substantial height cues created in the listener's brain due to the sound wave.  

 

That doesn't mean such a result of creating height for two channel playback isn't possible.  Q-Sound managed it though I don't know the algorithm they used.  So in principle it is possible.  In practice that resulting from minimal miking techniques is unlikely.  

 

So summarizing, stereo is capable of decent left to right accuracy for the listener.  Cues like loudness, reverb and FR changes allow some sense of depth though depth isn't accurately portrayed.  Nor does stereo contain the information to extract actual accurate depth upon playback.  Stereo likely will not create perception of height.  

[gmgraves]

14 hours ago, STC said:

 

It doesn’t matter whether they were multi miked or recorded at different time. What matters is if you are good recording and mixing engineer, you could pan pot those recording and create a stereo recording which when played over a stereo system will still create the illusion of soundstage and phantom image. Do you think norah jones Come away vocal was recorded with a stereo microphone?

Frankly I don't know what a Norah Jones is, and I don't care. If it isn't recorded with a stereo pair of microphones then it isn't stereo. If you call it stereo, then you are using a misnomer. multitrack, multi-mike recordings where things are "pan-potted" into position simply are not stereo. They do not meet the criteria for the definition of stereo, and are no more stereo than a 78 RPM shellac record is!

[gmgraves]

5 hours ago, STC said:

 

I don’t think so. A mono recording is still a mono even if you use stereo mode.  The stereo is the same sound with different level and phase over two speakers.  One mono on the left and another mono on the right can be argued as mono.

Actually it's two-channel mono (and sometimes three-channel mono)! There is an old saying that I think has a great deal of validity: "The beginning of wisdom is to call all things by their proper name." Calling a giraffe a rhinoceros will not make a giraffe into a rhinoceros, and calling a two-channel recording mixed-down from a number of monaural feeds, stereo, will not make it stereo. It really is that simple. 

[gmgraves]

7 hours ago, adamdea said:

You seem to be saying that

a. a pure stereo mic pair records everything direct and  indirect sound at that point in space.

b. if this is reproduced it will reach the listener and his head can do the work just as it would do if his ear was at the same pont in space as the mic.

 

That part is right. But the rest of your post is over-thinking the process. The simple result is that at somewhere between the musician(s) playing on the stage, and the back of the auditorium (or other venue), a pair of stereo microphones intercepts the sound field being projected by the musician(s). Both of the two microphones see the entire sound field (in a stereophonic recording) but they see it from a different perspective. This difference contains three different parameters which mark the difference between the two channels: intensity differences (between the two mikes), time arrival differences, and phase differences. For instance, both mikes pick up the same trumpet on the left side of the stage, but the nearest mike "hears" it first, "hears" it slightly louder, and "hears" it slightly out of phase from how the right microphone "hears" it. If you think about it, that's how humans (and much of the animal kingdom) localizes sounds as well. When one plays that recording back, on speakers, the speakers maintains and projects that same relationship. Those three sound characteristics wash over our heads and ears, and the three characteristics reconstruct that sound field that the microphones intercepted, and we respond to it by being able to localize the component parts of that sound field from those cues within our own brains.  

 

Also, while I'm thinking about it, let me clear up another point. Stereo recordings have two totally different goals depending on the musical performance that one is trying to capture. Goal number one is to transport the listener to the space where the symphony orchestra, wind ensemble, jazz dance band, or any other large musical ensemble is playing. I want to hear the Vienna Philharmonic playing in the Vienna Symphony Hall, for instance. On the other hand, goal number two is to bring a small, intimate ensemble such as a string quartet or small jazz group into the listener's living room. These two disparate requirements require wildly different techniques, yet they can both be done, and done well with a simple stereo microphone setup. One just has to use them differently. Obviously the mikes have to much closer for that intimate sound that's going to bring the small ensemble into one's room, and they're going to have to be a longer way away, accepting more ambience into the microphones to give the sense of being transported to the place where the performance is taking place.

 

Lastly, and hopefully entertainingly, It takes practice and experimentation to know how to do both large-scale and intimate well, and believe me I've made a lot of mistakes over the years!

How about getting the cylindrical stereo mike 180 degrees backwards? Making the whole recording with the mike facing the audience with it's back to the music? How about while using a laptop running Audacity to capture a performance, getting interrupted by a well meaning patron who wanted to to talk about recording while I was setting-up? The result? I forgot to point Audacity, in software, toward the FireWire port which was connected to my ADC from my mixer! Halfway through the first number, I noticed that the R & L Vu-meters on Audacity were both registering as if they were receiving a mono signal! A frantic look around showed me what I had done. Audacity was "looking" at the laptop's built-in voice microphone, not at the mixer/ADC via the FireWire port! Luckily, I used a Zoom H2 wired directly to the mixer and set to 24/96, as a backup recorder so all was not lost. The client thought the recording sounded fine, but I knew that it wasn't as good as it would have been had I captured the performance to Audacity on the laptop! Believe me, there have been many more, my friends; many more!

[gmgraves]

6 hours ago, pkane2001 said:

 

Don't know why this is even an argument. I have a simple EQ unit that will generate variable phase and level differences between left and right channel, even when fed mono input. Isn't this an example of mono recording to stereo playback?

 

Not recorded using a stereo mike technique? Not stereo. Stereo means "solid"; three-dimensional as in height, depth, and width as in stereophonic or "three-dimensional sound". It does not mean "two"! 

A multiplicity of mono channels mixed down to two channels can only do width. Therefore, it's not stereo. This is not really debatable. You might as well argue that the word "Democracy" (another Greek -derived word just like "stereophonic") doesn't mean a government where the people vote for leaders and/or laws. It's pretty well proscribed.

[pkane2001]

53 minutes ago, gmgraves said:

Not recorded using a stereo mike technique? Not stereo. Stereo means "solid"; three-dimensional as in height, depth, and width as in stereophonic or "three-dimensional sound". It does not mean "two"! 

A multiplicity of mono channels mixed down to two channels can only do width. Therefore, it's not stereo. This is not really debatable. You might as well argue that the word "Democracy" (another Greek -derived word just like "stereophonic") doesn't mean a government where the people vote for leaders and/or laws. It's pretty well proscribed.

 

I don't know of any native Latin speakers that can confirm the original meaning of the word as applied to audio, but quite a few that can confirm the current English usage:

 

Wikipedia: Stereophonic sound or, more commonly, stereo, is a method of sound reproduction that creates an illusion of multi-directional audible perspective

 

Online dictionaries

 

stereo sound

reproduction of sound using two or more separate microphones to feed two or more loudspeakers through separate channels in order to give a spatial effect to the sound

 

stereo

Sound that is directed through two or more speakers so that it seems to surround the listener and to come from more than one source; stereophonic sound.

 

stereophonic

of, relating to, or constituting sound reproduction involving the use of separated microphones and two transmission channels to achieve the sound separation of a live hearing

 

stereo

a way of recording or playing sound so that it is separated into two signals and produces more natural sound

 

[STC]

3 hours ago, gmgraves said:

Frankly I don't know what a Norah Jones is, and I don't care. If it isn't recorded with a stereo pair of microphones then it isn't stereo. If you call it stereo, then you are using a misnomer. multitrack, multi-mike recordings where things are "pan-potted" into position simply are not stereo. They do not meet the criteria for the definition of stereo, and are no more stereo than a 78 RPM shellac record is!

 

Are you aware that the so called stereo microphones are nothing more than but a pair of mono microphones placed in different configurations?  

 

I quoted Come away with me because it won best engineering Grammy award and thought it maybe an album of interest in recording field. 

 

 

[mansr]

1 hour ago, gmgraves said:

Not recorded using a stereo mike technique? Not stereo. Stereo means "solid"; three-dimensional as in height, depth, and width as in stereophonic or "three-dimensional sound". It does not mean "two"! 

In that case, a two-microphone recording doesn't qualify either.

[mansr]

16 minutes ago, STC said:

I quoted Come away with me because it won best engineering Grammy award and thought it maybe an album of interest in recording field. 

They could have gone easier on the reverb. Then again, with such bland music, I suppose they had to do something.