Blue or red pill?

[gmgraves]

43 minutes ago, Kal Rubinson said:

But the ceiling (or lack of one) is responsible for a portion of the ambiant sound field.

 

That is also a consideration.

[fas42]

Of course, one could just record in mono - and all these 'questions' go away ... I find pure mono recordings just as satisfying as stereo, savouring them as musical experiences. So, I can locate the bits, left to right, in "proper stereo" - big deal!

[mansr]

22 minutes ago, gmgraves said:

If one microphone is significantly higher than the other, then you are right. There will be some phase shift. But if the two stacked microphones are almost touching one another, the microphones' vertical pickup patterns are not precise enough for there to be any noticeable or even measurable difference. It's a lot like using two omni-directional microphones in an X-Y, A-B, or Blumlein coincident configuration. The result will be dead mono. There will be absolutely no difference between what the left microphone "hears" and what the right microphone hears. Yet, do the same experiment with two cardioids and you get glorious and real stereo!

I'm not disagreeing. What I objected to was the idea that there would be somehow be a cancellation of some frequencies.

[lmitche]

1 hour ago, Kal Rubinson said:

But the ceiling (or lack of one) is responsible for a portion of the ambiant sound field.

Yes, the difference in the arrival times of first arrival, floor and ceiling bounces likely account for the perception of height.  I'll have to listen to some outdoor concerts to learn what happens there. Similar timing differences likely add spatial perception on the horizontal as well.

[STC]

1 hour ago, Kal Rubinson said:

But the ceiling (or lack of one) is responsible for a portion of the ambiant sound field.

 

Reflection from the ceiling is essential mono (Bernanek?).

 

From what I observed at the our own concert hall with adjustable ceiling height during the technical briefing, it was useful to adjust the perceived loudness level of large and solo performance. It was demonstrated where the technical director was giving the briefing without any aid of amplified sound and yet the loudness level increased when the ceiling was lowered. 

 

 

 

 

Image source: http://dfp.com.my/

 

[fas42]

27 minutes ago, lmitche said:

Yes, the difference in the arrival times of first arrival, floor and ceiling bounces likely accounts for the perception of height.  I'll have listen to some outdoor concerts to learn what happens there. Similar timing differences likely add spatial perception on the horizontal as well.

 

What matters is that our ear/brain is very, very clever at sorting out what the sound field means - vastly more than the simplistic sound reaching the left versus the right lobes at different times explanations, always put up in audio forums, ever give credence to - we're not robots when hearing! What we perceive can be manipulated by knowing how that extra cleverness works - some interesting experiments are being done in Auditory Scene Analysis, exploiting those "higher levels of interpretation".

 

With recordings, this cleverness can only be useful if all of the key information is not so blurred and confused as to be counter-productive. The latter is what yields messy, unlistenable to recordings, when playback quality is not sufficient - the brain gives up trying to make sense of it.

 

While one attempts to explain everything using simple arithmetical explanations of the sound waveforms, then one will always fail to appreciate what the mind is capable of - and better subjective quality will still remain far out of reach, no matter how hard you stretch to grab it ...

[lmitche]

9 minutes ago, fas42 said:

 

What matters is that our ear/brain is very, very clever at sorting out what the sound field means - vastly more than the simplistic sound reaching the left versus the right lobe at different times explanations always put up in audio forums, ever give credence to - we're not robots when hearing! What we perceive can be manipulated by knowing how that extra cleverness works - some interesting experiments are being done in Auditory Scene Analysis, exploiting those "higher levels of interpretation".

 

With recordings, this cleverness can only be useful if all of the key information is not so blurred and confused as to be counter-productive. The latter is what yields messy, unlistenable to recordings, when playback quality is not sufficient - the brain gives up trying to make sense of it.

 

While one attempts to explain everything using simple arithmetical explanations of the sound waveforms, then one will always fail to appreciate what the mind is capable of - and better subjective quality will still remain far out of reach, no matter how hard you stretch to grab it ...

Well yes, of course. Just think about the fact that we can record vibrations from multiple instruments using a diaphragm that is capable of being in one only position at time, convert it to an electric signal that can only be in one position at a time, and then pump it to speakers that can be in only one position at a time, reaching an eardrum that can be only one in position at a time, and somehow the ear and brain can unmix the signal into the original multiple vibrating sources.  Completely amazing!

[STC]

As far as I know and based on extensive research on surround sound by scholars, Stereo sound do not have height information. Having said that, I have on may occasions perceived height.One good example is the VOG in Amused to Death Album. But it was a QSound recording and I need to double check whether it was real height or my imagination.

 

 It is normal for speakers to display varying heights within the physical speaker's size but I don't think it is possible for the sound to extend significantly above the speaker's edges for height. If at all, you perceive sound coming way above the speakers then it could be due to ceiling reflection.

 

The accepted position about the various recording formats is as shown in this table by Theile and Wittex. That is the accepted position. 

 

 

 

[fas42]

I looked around to find the work by Theile and Wittex, and in doing so came across this very recent paper, http://www.pnas.org/content/109/29/11854.full.pdf , "Emergence of neural encoding of auditory objects

while listening to competing speakers" - no, people speakers . This is an investigation of what occurs in the neural regions of the human brain, when it selectively focuses on one auditory object, amongst one or more other such objects. I'm very interested in this research, because it is directly investigating how I perceive what is occurring in the sound field of competent audio playback - this shows in part how the brain operates when dealing with complex combinations of sound, and can focus on what interests the mind, at a particular moment.

[Audiophile Neuroscience]

15 hours ago, mansr said:

No. Did you read nothing of what I wrote? There is no way to distinguish a near source from a more distant louder one. Any perception of depth or height in a stereo recording is our mind making things up based on what things usually sound like, possibly combined with room reflections. Have you ever noticed how the moon looks bigger when it's low in the sky? That's also our mind applying patterns that are usually right (objects overhead tend to be nearer than objects at the horizon) but fail in this extreme case.

 

Yes I read it carefully and agree FWIW with the logic . I gave you examples of how I thought aural depth perception could possibly be captured in a stereo recording that in no way impinges on, or contradicts anything you have said......Other than your persistent conclusion which is that it is not possible. IOW I agree with your premises , not your conclusion. The evidence that @esldude provided just happened to explain depth perception in recordings  as I did ( I aslo postulated frequency changes/Doppler in addition to volume and reverberation). More importantly their experiment offered confirmation ie Evidence.

Those real life cues of changes in volume and reverberation which subserve depth perception are not imaginary, not extrapolations based on what we expect to hear, but are physical phenomena in the real physical world that make their way on to the real physical recording. Whats more they operate in the same XY dimensional plane that lateral spatial locations occur. In the case of depth perception it doesn't matter that the mic pickups are symmetrical as the encoding mechanism is substantially different in both cases. This is exactly concurs with the evidence provided in Esldude's reference.

 

Do you deny this evidence?....but before answering.....

 

You say depth (and height) are illusions, "our mind making things up". I have no issue with this per se but - so what? The central phantom image is an *illusion too* .An illusion lets say we all hear (you included) and lets say we all agree is created by real information in the recording which makes its way into the audio signal, out the speakers, shakes hands with the room and then we hear it. So, it is also an illusion the genesis of which is measurable in terms of real physical cues. According to your logic, as you have stated numerous times (if it is in the recording (and presumably the audio signal), it is measurable.

 

15 hours ago, semente said:

 

I think that what's coming in the signal is the stereo effect, which results from your brain merging two "snaps" from a slightly different "perspective".

 

Sure, maybe, but the physical cues still must be there

 

12 hours ago, adamdea said:

I'm puzzled by this post, in the light of the your earlier discussion about your background. Have you actually studied auditory perception ie how it works. It's just that I have the impression that you are bit vague about how human beings identify spatial location (especially height, but now we are onto depth).

 

Hi, I explained a little of how auditory perception works in healthy unimpaired people.

 

 

Quote

 

 

 

Of course our primary method of locating sounds is vision.

 

I'm sorry this is something of an oxymoron. You cannot see sound. You can feel sound pressure and see its consequences but you cant see it or smell it. They are separate somatosensory phenomena, neural circuitry and cortical mappings. Yes of course it helps to know where to focus attention and yes seeing the object of the sound source complements that process. That is distinctly different to assuming the latter is the main way we localize sound. You will need to provide evidence. Indeed blind people not only can still localize sounds, their ability to do so is often enhanced.

 

 

 

Quote

Depth might be perceived for a number of reasons in a recording and in some ways  it can be encoded for gross effects (offstage noises processed to have lots of reverb and hf filtered will sound distant; I don't know whether it can really be done for height at all). But pinpoint depth?.

 

 

I never claimed pin point depth just sufficient to perceive relative closeness and layering. This together with laterality info allows localization.

I have already said that I don't have an explanation of height in recordings.

 

 

11 hours ago, adamdea said:

Beyond inter-channel volume and time differences, this gets tricky. It may be a false starting point to assume that there are consistent responses between people to particular recordings beyond from left-right. Maybe not even then as regards precise width.

 

 

It is precisely these inconsistent responses amongst the population that prompted this thread. Some people hear it,others don't. There is no assumption on my part that responses will be consistent for everyone.Of the group of individuals who do consistently hear differences, the question is why.

 

3 hours ago, Kal Rubinson said:

But the ceiling (or lack of one) is responsible for a portion of the ambiant sound field.

 

+1

 

3 hours ago, gmgraves said:

In most concert halls, when the percussionist hits the triangle, it seems to float above the left side of the orchestra. Yes, it's an auditory illusion, but a true stereo mike setup will capture that effect and replay it in ones listening room where it seems to float above the left speaker.

 

This is precisely the point I am unsuccessfully trying to make to Mans.......and that the physical cues when captured in the recording, or artificially added by engineers, should be measurable.

 

Quote

 

Also, usually in most large ensembles, the brass instruments in are in the last row back and usually on risers. That means that they "speak" from higher-up than do the woodwinds in front of them and the violas and cellos in front of the woodwinds. Couple that ability with the front-to-back layering that real stereo imparts and you get the ability to pinpoint each instrument in three dimensional space right-to-left, front-to-back, and height off the floor. When done right the imaging can be jaw-dropingly  uncanny!

 

George, you must have been to my place , totally agree

[STC]

38 minutes ago, fas42 said:

I looked around to find the work by Theile and Wittex, and in doing so came across this very recent paper, http://www.pnas.org/content/109/29/11854.full.pdf , "Emergence of neural encoding of auditory objects

while listening to competing speakers"

 

 

It is https://www.researchgate.net/publication/268188418_Principles_in_Surround_Recordings_with_Height

[fas42]

34 minutes ago, STC said:

 

 

It is https://www.researchgate.net/publication/268188418_Principles_in_Surround_Recordings_with_Height

 

Thanks, I was able to track it down.

[fas42]

When everything is 'working right', in a system, it all comes together: the sense of space, depth; the ability to listen to, and enjoy, "appalling" recordings; being able to play at totally realistic levels, and have people who have no interest in audio whatsoever listen to such without even noticing the volume - there are no downsides, in any areas.

 

When people experience this in special cases or circumstances, it's a hint of what's possible, if one chooses to pursue the endeavour of extracting this level of performance.

[acg]

17 hours ago, mansr said:

No. Did you read nothing of what I wrote? There is no way to distinguish a near source from a more distant louder one. Any perception of depth or height in a stereo recording is our mind making things up based on what things usually sound like, possibly combined with room reflections. Have you ever noticed how the moon looks bigger when it's low in the sky? That's also our mind applying patterns that are usually right (objects overhead tend to be nearer than objects at the horizon) but fail in this extreme case.

 

The moon looks bigger at the horizon because we are looking through more atmosphere.   Look up refraction and you will get an idea why... it has nothing to do with 'applying patterns' as you suggest. 

[Audiophile Neuroscience]

40 minutes ago, acg said:

 

The moon looks bigger at the horizon because we are looking through more atmosphere.   Look up refraction and you will get an idea why... it has nothing to do with 'applying patterns' as you suggest. 

Yes I forgot to mention this, thanks. It certainly changes the colour perception but I'm not sure it explains the size illusion.No matter, the important thing would be to see if the same physical cues that create the illusion in the first place can be recorded to recreate the illusion.The mind must have cues to work from to create shared illusions (as opposed to individual hallucinations generated inside the brain and in no one elses brain).

 

Edit: illusions arise from altered or mis-perception or distortion of real world external stimuli, they are often shared with peers, to variable degrees. There has to be real world stimuli. Whether this is the brain being "tricked" or just normal and clever creativity on the part of the brain is a matter of opinion.

 

[Sonicularity]

30 minutes ago, acg said:

 

The moon looks bigger at the horizon because we are looking through more atmosphere.   Look up refraction and you will get an idea why... it has nothing to do with 'applying patterns' as you suggest. 

I don't believe that is true from the information that I found about the topic.  Where do you see evidence to suggest this?

[acg]

54 minutes ago, Sonicularity said:

I don't believe that is true from the information that I found about the topic.  Where do you see evidence to suggest this?

 

Light travels in a straight line...right?  Only when the medium through which it travels is of homogenous density.  Otherwise it bends from high density toward low density...slowly.  In the case of the light travelling to the Earth it bends from high density atmosphere closer to the surface toward lower density atmosphere further up thus forming a curve rather than a straight line.  There are all sorts of equations for it but basically the curvature is dependent on the density gradient and the distance which are in turn influenced by temperature and barometric pressure et cetera.

 

It is basic physics and you can choose to disbelieve if you like.  This is why telescopes point straight up into the sky.  It is why any decent GPS will not use satellites close to the horizon.  It is why a field levelling contractor can only be accurate about 400m metres from a laser.  It's why surveyors have to make optical observations from both directions.  And so on and so forth.

 

 

[mansr]

7 hours ago, acg said:

The moon looks bigger at the horizon because we are looking through more atmosphere.   Look up refraction and you will get an idea why... it has nothing to do with 'applying patterns' as you suggest. 

If you measure the angle occupied by the moon when near the horizon and again when high in the sky, you get almost exactly the same value. Nevertheless, the rising or setting moon is often perceived as twice the size of the moon when (more or less) overhead. Atmospheric refraction can't explain this.

[Don Hills]

Indeed. If the refraction in the atmosphere caused a significant apparent size difference when the moon is close to the horizon, the varying refraction due to the varying atmospheric density would make the moon look egg-shaped.

[botrytis]

Also, light bends due to gravity, why black holes look black, They absorb any light coming near them.

[mansr]

8 hours ago, Audiophile Neuroscience said:

You say depth (and height) are illusions, "our mind making things up". I have no issue with this per se but - so what? The central phantom image is an *illusion too* .An illusion lets say we all hear (you included) and lets say we all agree is created by real information in the recording which makes its way into the audio signal, out the speakers, shakes hands with the room and then we hear it. So, it is also an illusion the genesis of which is measurable in terms of real physical cues.

Lateral positioning in stereophonic reproduction is an illusion, yes, Importantly, it is a deliberately crafted illusion. Depth and height, on the other hand, are unintentional illusions. The recording makes no attempt to capture the actual depth and height of sound sources. The cues it can convey do not in themselves actually indicate depth or height, not at a live event and not in a recording. They do, however, trigger the same perceptions in either situation.

[pkane2001]

11 minutes ago, Don Hills said:

Indeed. If the refraction in the atmosphere caused a significant apparent size difference when the moon is close to the horizon, the varying refraction due to the varying atmospheric density would make the moon look egg-shaped.

 

Easy to prove this. Take a photo of the moon over the horizon, and another when it's overhead. You'll see that the angular size doesn't change.

[semente]

59 minutes ago, mansr said:

If you measure the angle occupied by the moon when near the horizon and again when high in the sky, you get almost exactly the same value. Nevertheless, the rising or setting moon is often perceived as twice the size of the moon when (more or less) overhead. Atmospheric refraction can't explain this.

 

A well known trick in photography and painting is to use the human figure, a construction or a vehicle to add scale to a featureless landscape that would otherwise be difficult to characterize.

[adamdea]

9 hours ago, Audiophile Neuroscience said:

 

I'm sorry this is something of an oxymoron. You cannot see sound. You can feel sound pressure and see its consequences but you cant see it or smell it. They are separate somatosensory phenomena, neural circuitry and cortical mappings. Yes of course it helps to know where to focus attention and yes seeing the object of the sound source complements that process. That is distinctly different to assuming the latter is the main way we localize sound. You will need to provide evidence. Indeed blind people not only can still localize sounds, their ability to do so is often enhanced.

 

Are you aware of the phenomenon of visual steering. I am not suggesting that blind people can't localise sounds- I'm saying that normally sighted individuals in everyday life do use vision to localise sounds, or rather their experience of sound localisation is  at least partially determined (where they can see the presumed source of the sound) by the visual information. I'm not suggestign that we can;t or don;t use audio information. But If the audio and visual information don't match the vision wins (interestingly the other way round for timing information). And that means you "hear" the sound in a different place from the real place it is coming from and do not perceive a struggle. In that sense you really do "hear" things you see.  And this is just an example of multisensory integration. Our "hearing impressions" come at least in part from non audio sources. [for another example IIRC different coloured objects sound louder or less loud according to their colour.]

 

Do I need to provide evidence of a well understood process? I'm not trying to raise the temperature but I can't help wondering whether you have taken into account multisensory integration in your starting point ie your model of how and to what extent we can localise sounds in real life. It would not be wise to assume that everything we experience in real life which we perceive as an auditory phenomenon could be replicated using only sound information. Perhaps my ealier formulation was little over egging the pudding but the general point is that we plug auditory information into a model (which includes other inputs which include vision and other bits of information) to get an output

 

As for the rest of your long post- in your debate with Mansr you seem unwilling to consider the distinction between the question of whether spatial information can be encoded and the question of whether it can or might be perceived (sometimes) as result of the sensory system. He is saying that you can't encode height information. That is not the same as saying that as a result of a perceptual model you might not perceive it by eg assuming that high pitched sounds come from higher up. But since we all have different hrtfs these perceptual effects are bound to vary. It seems to me that this provides the the answer to the question of why real phenomena in the recording produce   particular effects in some people whilst not producing them in other people (and possibly not even producing a consistent result amongst those who experience them) . It also means that one has to be careful about calling those phenomena auditory cues in the same way that say inter aural time and amplitude differences are- the latter can be applied pretty precisely in a panpot with predictable results. 

 

As for depth I think we are agreed that by manipulating the amount of direct and indirect sound we can create some sort of sense of depth. But does that mean that it is because of reliably encoded auditory information that some people feel that they can tell in an orchestral recording that the flutes are in the middle 4 feet behind the middle of the strings just like they can when they see a live concert. 

 

[semente]

It would be interesting to record with a vertically oriented ORTF setup and then play back with one speaker on the lower and the other on the top shelf of a bookcase.

I'm willing to bet that such a setup will give you height but no width - all instruments will be virtually playing from a vertical line positioned between the two speakers. It might be more difficult or near impossible to determine depth.