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Cochlear nonlinearities

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32 minutes ago, JanRSmit said:

Is this proven, or your assumption.?

Many years ago, audax had a tweeter going to over 40khz. We did a test plating the tweeter out of sight in a room and played a 30khz tone. When people came in the room for meetings, after a short while they became restless, sort of disturbed, but no clue as what caused it. Then after stopping playing, the restless behaviour dissapeared. I also remember Goldmund , just started then, referred to research by military dealing with human audibility of impulses, concluding that the audibility threshold is well above 20khz. 

Are you claiming that all senses of vibration are encompassed in what is heard?  That kind of 40kHz audibllity might not be through hearing, but another sense of vibration.   I can detect some kinds of vibration from senses other than hearing.

 

Even if the 'ears' detect that vibration, people weren't saying that they 'heard' the vibration, but rather they became 'restless'.  Okay, some kinds of so-called music makes me restless, but obviously not the same mechanism as the 40kHz vibration does.

 

John

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On 7/6/2019 at 1:52 PM, jabbr said:

 

 

Thats bone conduction. Bone conduction might indeed be relevant for audio reproduction. 

 

So you listen with speakers pressed hard to your skull?

 

Oh, those interested might want to research what is actually being heard with bone-injected ultrasonics.


perception = controlled hallucination, hallucination = uncontrolled perception

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On 7/6/2019 at 2:40 PM, JanRSmit said:

Is this proven, or your assumption.?

 

That is what I read in one or more reports, many years ago. So no assumption.

 


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On 7/6/2019 at 3:16 PM, John Dyson said:

Are you claiming that all senses of vibration are encompassed in what is heard?  That kind of 40kHz audibllity might not be through hearing, but another sense of vibration.   I can detect some kinds of vibration from senses other than hearing.

 

Even if the 'ears' detect that vibration, people weren't saying that they 'heard' the vibration, but rather they became 'restless'.  Okay, some kinds of so-called music makes me restless, but obviously not the same mechanism as the 40kHz vibration does.

 

John

How we as human beings sense vibrations is definitely not limited to our hearing system. And how we interpret the vibrations we sense is not only music of noise. It also triggers emotions and body movements like tapping with your feet, etc. 

 

 

 

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On 7/5/2019 at 2:37 AM, jabbr said:

With respect to the question of whether audio frequencies >20 kHz might have an effect on audio perception, it has been often assumed that:

 

1) assume cochlea acts linearly

2) assume basilar membrane does not vibrate >20 kHz due to the anatomy of the cochlea

 

The question really comes down to whether the cochlea acts linearly because if not, then just as high frequency electrical components can cause intermodulation distortion (IMD) so might ultrasonic frequencies affect audio perception.

 

[1] This paper discusses: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6366996/#R30 -- in  particular look at figure 6 -- the thick black line shows response at 22 kHz and presumably greater frequencies!

 

[2] This paper discusses the mechanics of basilar membrane vibration in detail: https://pdfs.semanticscholar.org/6f0a/46befffa8710ebb606ed3dec06d7be317be1.pdf?_ga=2.6977266.115791992.1562285968-561089348.1562285968

 

There are, of course many other scientific papers which bring the notion of cochlear nonlinearities into discussion, and provide mechanisms for ultrasonic effects but these two might give folks a start.

 

The folks who assume there is some absolute law of biophysics that allows the cochlea to be modelled linearly might want to read and understand these in detail --- the situation to me is not so perfectly clear.

 

Feel free to post other scientific studies which either support or refute these ideas (there are many many)

 

As dat is i onderstand this stuff, it for one confirms that for audible sound levels up to about 50 decibels our hearing system is quite linear. Above that level of becomes increasingly non linear. In the late 70'ties this was already explained to me by medical hearing specialists.

 

Makes you wonder if this is taken into account with listening tests .

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2 hours ago, Fokus said:

 

So you listen with speakers pressed hard to your skull?

 

Oh, those interested might want to research what is actually being heard with bone-injected ultrasonics.

 

You are thinking about this in a linear fashion. When I listen to a chorus I don’t hear each individual voice. Likewise listening to a symphony. 

 

Nor or do I listen to each tone nor harmonic. Sounds naturally modulate eachother. 


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1 hour ago, JanRSmit said:

As dat is i onderstand this stuff, it for one confirms that for audible sound levels up to about 50 decibels our hearing system is quite linear. Above that level of becomes increasingly non linear. In the late 70'ties this was already explained to me by medical hearing specialists.

 

Do you mean the response of the cochlea or hearing system in general? For one: what is known about neuroscience is vastly vastly more since the 1970s eg computationally & mathematically. The system is highly nonlinear. Medical hearing specialists in the late 1970s wouldn’t have understood that.


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1 hour ago, JanRSmit said:

How we as human beings sense vibrations is definitely not limited to our hearing system. And how we interpret the vibrations we sense is not only music of noise. It also triggers emotions and body movements like tapping with your feet, etc. 

 

 

 

 

Yes! More than that— low frequencies <20 Hz can be directly felt. This all becomes part of the music experience. 


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On 7/6/2019 at 7:40 AM, JanRSmit said:

Is this proven, or your assumption.?

Many years ago, audax had a tweeter going to over 40khz. We did a test plating the tweeter out of sight in a room and played a 30khz tone. When people came in the room for meetings, after a short while they became restless, sort of disturbed, but no clue as what caused it. Then after stopping playing, the restless behaviour dissapeared. I also remember Goldmund , just started then, referred to research by military dealing with human audibility of impulses, concluding that the audibility threshold is well above 20khz. 

Oh so the illusive proof of ultrasonics is restless people and secret military research.  Goldmund has been around since 1978.  Any updates since then?

 

The restless thing should be an easy test to perform.  Maybe a few people could repeat it with video of this restless behavior. 


To paraphrase Rick James, "sighted listening is a helluva drug".

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2 hours ago, jabbr said:

This is production of sound in the audible band via demodulated ultrasound.  Hardly indicative of ultrasound being audible except when being used to produced below 20 khz sound.  The use of bone conduction ultrasound is not new, and also doesn't indicate normal listening is able to hear ultrasound.  


To paraphrase Rick James, "sighted listening is a helluva drug".

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1 hour ago, esldude said:

This is production of sound in the audible band via demodulated ultrasound.  Hardly indicative of ultrasound being audible except when being used to produced below 20 khz sound.  The use of bone conduction ultrasound is not new, and also doesn't indicate normal listening is able to hear ultrasound.  

 

I’m not sure you are grokking the full implications of this. 

 

1) Yes it’s possible that, like but not the same as intermodulation distortion, that the mechanism of ultrasonic affect on the cochlea is via this “demodulation” effect — not exactly demodulation but essentially subharmonics. So an ultrasonic signal, via nonlinearities, results in a specific pattern of cochlear excitation. 

2) This pattern might be unique to the individual and specific individual’s response to specific frequencies. 

3) Thus there is no global transform that would allow someone to “reencode” ultrasonic information in the 20-20kHz range. The mapping from 20-40 kHz to 20-20 kHz — or 20-11kHz is presumably specific to the individual. 

4) Thus ultrasonic information is necessary to contain the full experience, as heard by a person. 

 

5) That said it might be possible to “get close” to reencoding 24/96 into 24/44 by modeling an “average” air / cochlear nonlinearity.


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8 hours ago, JanRSmit said:

How we as human beings sense vibrations is definitely not limited to our hearing system. And how we interpret the vibrations we sense is not only music of noise. It also triggers emotions and body movements like tapping with your feet, etc. 

 

 

 

There are also DEFINITELY nonlinear mechanisms that can even be used to ultrasonically direct vocal messages to individuals from a long distance -- however, we aren't typically talking about such levels when listening to music from normal transducers.  Normal level ultrasonics aren't enough to make this situation happen -- it requires relatively high levels to drive the hearing system into deep nonlinearity.  Also, such mechanisms would not have exceptionally linear transfer functions.

 

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2 hours ago, jabbr said:

 

I’m not sure you are grokking the full implications of this. 

 

1) Yes it’s possible that, like but not the same as intermodulation distortion, that the mechanism of ultrasonic affect on the cochlea is via this “demodulation” effect — not exactly demodulation but essentially subharmonics. So an ultrasonic signal, via nonlinearities, results in a specific pattern of cochlear excitation. 

2) This pattern might be unique to the individual and specific individual’s response to specific frequencies. 

3) Thus there is no global transform that would allow someone to “reencode” ultrasonic information in the 20-20kHz range. The mapping from 20-40 kHz to 20-20 kHz — or 20-11kHz is presumably specific to the individual. 

4) Thus ultrasonic information is necessary to contain the full experience, as heard by a person. 

 

5) That said it might be possible to “get close” to reencoding 24/96 into 24/44 by modeling an “average” air / cochlear nonlinearity.

Sorry much too big a reach.  This isn't any explanation of how 96 khz would be better than 44.1 khz for music.  For one there is no consistent way that speakers respond to such frequencies.  Most don't have any appreciable response in the first place. 


To paraphrase Rick James, "sighted listening is a helluva drug".

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On 7/6/2019 at 8:40 PM, JanRSmit said:

Is this proven, or your assumption.?

Many years ago, audax had a tweeter going to over 40khz. We did a test plating the tweeter out of sight in a room and played a 30khz tone. When people came in the room for meetings, after a short while they became restless, sort of disturbed, but no clue as what caused it. Then after stopping playing, the restless behaviour dissapeared. I also remember Goldmund , just started then, referred to research by military dealing with human audibility of impulses, concluding that the audibility threshold is well above 20khz. 

 

You can do this with DSD recordings filtered at 20 and 50kHz. The ultra freq can have a positive or negative effect. There are research on monkeys where even a short exposure to these ultra sound can have lasting impact to them.

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1 minute ago, esldude said:

Sorry much too big a reach.  This isn't any explanation of how 96 khz would be better than 44.1 khz for music.  For one there is no consistent way that speakers respond to such frequencies.  Most don't have any appreciable response in the first place. 

 

And the Tinnitus study is a bit of a stretch, considering they used sound beaming with a 90kHz modulated carrier to direct audio signal to a listener. This type of beaming is extremely unlikely to occur under normal circumstances and requires a very loud carrier signal relative to the audio content it carries in order to trigger the non-linearities in the air to demodulate it. Cool technology, though ;)

 

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14 minutes ago, pkane2001 said:

And the Tinnitus study is a bit of a stretch,

That’s just one random study of many — point being that nonlinearities can decompose ultrasonic into sonic — that’s all — there are other studies and other mechanisms and other nonlinearities. 

 

How tight do you want to hold on to fixed beliefs despite research?

 

Dogma frequently breaks down when you look at little details.


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1 minute ago, jabbr said:

That’s just one random study of many — point being that nonlinearities can decompose ultrasonic into sonic — that’s all — there are other studies and other mechanisms and other nonlinearities. 

 

How tight do you want to hold on to fixed beliefs despite research?

 

You referenced the study to make a point, not me B|

 

I actually don't have a strong opinion on this.  But just because cochlea may be non-linear is not a proof that ultrasound makes any difference in hearing. Show me some proper studies that demonstrate that ultrasound at normal levels can be detected as part of musical material and I'll agree that it might matter for audio recording/playback.

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11 minutes ago, pkane2001 said:

You referenced the study to make a point, not me B|

 

The very specific point I was referencing is that nonlinearities might introduce Sonics as a result of ultrasonics. That’s all. 

 

I am saying that, based on the science we know, it is possible that 24/96 is audibly different than 16/44.1 at least in some circumstances. 

 

I have said many times that I’m not yet convinced either way. I am leaning toward a small difference in some circumstances. 

 

You should get the idea that I don’t adhere to the dogma that 16/44.1 encompasses all that we might ever hear. 


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29 minutes ago, jabbr said:

 

The very specific point I was referencing is that nonlinearities might introduce Sonics as a result of ultrasonics. That’s all. 

 

I am saying that, based on the science we know, it is possible that 24/96 is audibly different than 16/44.1 at least in some circumstances. 

 

I have said many times that I’m not yet convinced either way. I am leaning toward a small difference in some circumstances. 

 

You should get the idea that I don’t adhere to the dogma that 16/44.1 encompasses all that we might ever hear. 

 

I get it. There's no need to present studies that demonstrate that nonlinear systems cause subharmonics. That's a proven fact and can be modeled  by some math for any nonlinear system, as long as the transfer function is known.

 

What I don't see in any of the referenced studies is that the cochlea nonlinearity actually results in audible, detectable subharmonics from ultrasound. To my mind, until you can show that, all you have is a hypothesis about how it might possibly work. That's an interesting fact, but in no way a convincing proof of audibility.

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I'm in agreement with pkane here.  I'm not being dogmatic either.  It seems as if any credible info is a real stretch.  

 

If those higher bandwidths make a difference they must be very small to be this far down the road and not have clear repeatable evidence of it. The meta-study paper, which I'm not sure is selective enough in the tests it included, concluded a difference for higher sample rates vs standard was audible over thousands of responses 56% of the time. Over the 12,000 or so responses that is enough to say it is a for real difference.  But even then the difference is not large at only 50% null vs 56% real effect.  Most of the studies included had some heroic playback conditions with unusually wide bandwidth gear that applies to less than 1% or 2%% of normal high end audiophile systems.  And would apply to probably not even 1% of available recordings.  My current DAC can put out 25 times the bandwidth of my hearing.  So I guess I'm covered.  


To paraphrase Rick James, "sighted listening is a helluva drug".

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As someone who has been there many, many times ... it doesn't require the "magic" presence of particular frequencies to make playback deliver visceral impact, the immersive, involving quality that live music possesses... rather, it's the lack of certain types of distortion; the term "effortless" is often used in this context, and that's precisely what's needed.


Frank

 

http://artofaudioconjuring.blogspot.com/

 

 

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56 minutes ago, esldude said:

My current DAC can put out 25 times the bandwidth of my hearing.  So I guess I'm covered.  

 

 That's a lot of Ultrasonic rubbish . Are you letting your ears do the filtering for you ? :D

 

Incidentally, years ago a friend of mine had Plasma tweeters that he occasionally switched in and appeared to offer benefits,

 however on the way back home in the car on a couple of occasions my ears sounded weird a bit like with changes in altitude,


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you might as well give up your career as a tester. The difference between a reconstituted FLAC and full size WAV is much less than that, but it does exist. - Cookie Marenco"

 

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11 hours ago, jabbr said:

 

I’m not sure you are grokking the full implications of this. 

 

1) Yes it’s possible that, like but not the same as intermodulation distortion, that the mechanism of ultrasonic affect on the cochlea is via this “demodulation” effect — not exactly demodulation but essentially subharmonics. So an ultrasonic signal, via nonlinearities, results in a specific pattern of cochlear excitation. 

2) This pattern might be unique to the individual and specific individual’s response to specific frequencies. 

3) Thus there is no global transform that would allow someone to “reencode” ultrasonic information in the 20-20kHz range. The mapping from 20-40 kHz to 20-20 kHz — or 20-11kHz is presumably specific to the individual. 

4) Thus ultrasonic information is necessary to contain the full experience, as heard by a person. 

 

5) That said it might be possible to “get close” to reencoding 24/96 into 24/44 by modeling an “average” air / cochlear nonlinearity.

You would have to wear bone conduction headphones to get any effect, the power of the high frequencies from your speakers is not enough...

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12 hours ago, fas42 said:

As someone who has been there many, many times ... it doesn't require the "magic" presence of particular frequencies to make playback deliver visceral impact, the immersive, involving quality that live music possesses... rather, it's the lack of certain types of distortion; the term "effortless" is often used in this context, and that's precisely what's needed.

Yes -- that is the main thing.  Distortion is the big bugaboo...  Excess bandwidth opens up to more IMD reaching back into the audible range.  Almost all normal recordings (not ALL, but allmost all) into the 1990s'  have been touched by analog noise reduction systems.  Such systems are a nice, very effective source of distortion.  Such distortion is usually not very measurable by simple (even multiple) test tones.

The war that audio perfectionists should be fighting (if they are true perfectionists) is DISTORTION and good frequency response up to about 20kHz (plus or minus.)  This also includes good transient response.    Distortions are what makes the difference when there is an excess frequency response and material 'up there'.  Of course -- we who know -- a lot of the 'material' above 20kHz in actual, distributed recordings is indeed NR distortion (that is, for the material into the 1990s.)  Whatever 'audio' there is above 20kHz just adds to the distortion in the audible range given real-world analog hardware.

PS: part of my reason for extreme sensitivity against distortion is that I have heard/seen how much damage is done by at least some of the old NR systems.  It is amazing how bad.  If the distortion could be measured as easily as normal HD or NORMAL IMD -- it would never have been tolerated.

 

John

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