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Hypersonic Effect (HFCs etc ...)

Rather than once again take this post way off-topic, I thought I'd start another thread, as this interests me.

For reference here's krabapple's post:
http://www.hydrogenaudio.org/forums/index....st&p=606769

It strikes me that there's something going on with HFCs (high-frequency components), what it is exactly and whether it's even related to what we might call "audio" (i.e. something we can hear) is another matter.

What surprised me is that the study in question  doesn't seem to have attempted to isolate the effect of HFCs.

Wouldn't it have been more interesting if the source material was only HFCs - i.e participants in a room exposed to HFCs (> 25kHz) and then not exposed to HFCs who are then required to differentiate. That could easily follow ABX testing - i.e. this is the experience with HFCs, this is the experience without, now tell us when/whether A is X or Y.

Mixing it all in with audible content seems to throw too many variables into the pot.

I doubt whether the ears have a great deal to do with experiencing HFCs (which would explain the headphone result). My (complete) guess is that it's actually the skin that "feels" the ripples of very frequently changing air pressure. Perhaps we don't "consciously feel" this (in the sense that we identify that our skin feels the pressure fluctuations in the air) but it does something funny to our brains and we like whatever that is and then when that gets mixed in with the music we prefer the compound audible + inaudible effects to the purely audible.

Ultrasonic disintegration, Sonochemistry and Ultrasonic cleaning all operate in the low ultrasound (20kHz+) range (http://en.wikipedia.org/wiki/Ultrasound).

C.
PC = TAK + LossyWAV  ::  Portable = Opus (130)

Hypersonic Effect (HFCs etc ...)

Reply #1
Faith-based audiophiles sometimes accuse the science-based people of having closed minds. Occasionally it can look like that, which is why I bought into the original OT line, because I didn't think it reasonable to demand certain sorts of consciousness of effect: OTOH, it is perfectly reasonable to require people to express a sense of difference, which correlates with differences in the signals. If there were no consciously articulated sense of difference, then the purported brain activity would be of neurological, but not audio, significance.

But, the prior question is, "Do hypersonic effects exist?" And the only evidence seems to be this one article, which by its own account is at the limit of statistical significance, and some people think they did the statistics wrong. It contradicts a huge amount of prior work, and has methodological limitations, apparently. In the circs, the onus of proof is on the pro-hypersonics.  Some people want to believe that after all these years there has to be something better than CD, but it ain't necessarily so (for stereo).

Hypersonic Effect (HFCs etc ...)

Reply #2
I doubt whether the ears have a great deal to do with experiencing HFCs (which would explain the headphone result). My (complete) guess is that it's actually the skin that "feels" the ripples of very frequently changing air pressure. Perhaps we don't "consciously feel" this (in the sense that we identify that our skin feels the pressure fluctuations in the air) but it does something funny to our brains and we like whatever that is and then when that gets mixed in with the music we prefer the compound audible + inaudible effects to the purely audible. 

Ultrasonic disintegration, Sonochemistry and Ultrasonic cleaning all operate in the low ultrasound (20kHz+) range (http://en.wikipedia.org/wiki/Ultrasound).



Seems to me the diminution of energy of high-frequency audio signals in air, would be enough to discount the idea that we feel 'ripples' by the time it reaches our skin.  The only truly well-defined 'ultrasonic effect' is transduction via bone, which requires very close proximity to the source.

Oohashi's work shows several bizarre , even contradictory, results, suggesting something funny was going on with the method.  Why can subjects seem to discriminate sounds with HFC when participating in a 'quality evaluation' type test (MUSHRA-like) but not in an difference detection (ABX-type) test?  (I write "seem" because the statistics presented were rather murky).

Then there's the apparent case that the effect on brain physiology, takes ~10 seconds to set up, and persists for awhile after the stimulus is gone...?  What were they actually detecting here?  Brain scan data is notorious for requiring very careful extrapolation from data to meaning.

I also pointed out on that other thread that Nishiguchi et al's  attempt to indpendently replicate the work, that addressed some of its questionable points, failed to support the claim of 'hypersonic effect'

Finally, for any 'audiophiles' to claim this paper explains why SACDs sound better, (for example) is laughable, given the highly specialized nature of the test gear and signals.

Here btw are two of the more interesting HA threads (of several) previously discussing hte 'hypersonic effect' (among other things!)

http://www.hydrogenaudio.org/forums/index....p;hl=hypersonic

http://www.hydrogenaudio.org/forums/index....showtopic=40134

Hypersonic Effect (HFCs etc ...)

Reply #3
My comment in the thread carpman linked saying that for someone to distinguish two things in order to express a preference meant they must be consciously aware that they are different was based on the assumption that this study conducted a proper blind test designed to statistically prove that individual participants weren't simply guessing.

I guess I was wrong in making that assumption.
Is 24-bit/192kHz good enough for your lo-fi vinyl, or do you need 32/384?

Hypersonic Effect (HFCs etc ...)

Reply #4
The research is interesting none the less, but was this the paper that Sony based their research on when they were developing the SACD? This author who coined the term "the hypersonic effect" seems to be a neurophysiologist not an engineer? The way I perceive it is it's kind of like comparing apple's to oranges?

Another link which I found interesting:

http://www.action-net.co.jp/ar/media/Actio...d/index2-e.html
budding I.T professional

Hypersonic Effect (HFCs etc ...)

Reply #5
Seems to me the diminution of energy of high-frequency audio signals in air, would be enough to discount the idea that we feel 'ripples' by the time it reaches our skin.  The only truly well-defined 'ultrasonic effect' is transduction via bone, which requires very close proximity to the source.

Is this a well understood / studied area?
I mean, isn't that also the case for bats? Surely whatever hits a bat's ear also hits our skin.

As I said, I really doubt this has anything to do with audibility, and unfortunately I don't know enough to know whether this ... 
Quote
it has been suggested that infrasonic exposure may possibly have an adverse effect on human health (Danielsson and Landstrom 1985), suggesting that the biological sensitivity of human beings may not be parallel with the "conscious" audibility of air vibration. Second, the natural environment, such as tropical rain forests, usually contains sounds that are extremely rich in HFCs over 100 kHz. From an anthropogenetic point of view, the sensory system of human beings exposed to a natural environment would stand a good chance of developing some physiological sensitivity to HFCs. It is premature to conclude that consciously inaudible high-frequency sounds have no effect on the physiological state of listeners.
Source: http://jn.physiology.org/cgi/content/full/83/6/3548

... is nonsense.

C.
PC = TAK + LossyWAV  ::  Portable = Opus (130)

Hypersonic Effect (HFCs etc ...)

Reply #6
Quote
Second, the natural environment, such as tropical rain forests, usually contains sounds that are extremely rich in HFCs over 100 kHz. From an anthropogenetic point of view, the sensory system of human beings exposed to a natural environment would stand a good chance of developing some physiological sensitivity to HFC

Ignores the biological cost of additional sensory abilities, and the established history of primate evolution.

We also evolved in an environment relatively rich in UV radiation.  Butterflies and many other insects use it as their primary wavelength of vision.  Why aren't we able to see it at all?  Because it offers us a survival advantage not great enough to justify the cost.

Primates in general, and humans in particular, are sensory generalists and have greatly diminished perception ranges when compared to the diversity of the animal kingdom as a whole, and even other mammals.
Creature of habit.

Hypersonic Effect (HFCs etc ...)

Reply #7
We also evolved in an environment relatively rich in UV radiation.  Butterflies and many other insects use it as their primary wavelength of vision.  Why aren't we able to see it at all?  Because it offers us a survival advantage not great enough to justify the cost.

Well if HFCs operate like UV, as per your example, that backs up entirely what I'm suggesting and what the report in part seems to suggest [notice the part you quoted says nothing about hearing, only a "physiological sensitivity to HFC" *].

We don't see UV as colour, BUT we feel its effect on our skin.
We don't hear HFCs as audio, BUT perhaps we feel its effect on our skin.
That's all I'm saying.

As I've said, a number of times, I doubt HFCs have anything to do with audibility.

C.

[* EDIT: Added the quote from the report]
PC = TAK + LossyWAV  ::  Portable = Opus (130)

Hypersonic Effect (HFCs etc ...)

Reply #8
I chose my words carefully, and said nothing about whether HFC has an effect on the human body, simply that we are unlikely to have a primary sensory organ sensitive to its reception.

To be pedantic, though, we do not feel UV on our skin, rather we feel the secondary effects of UV radiation on our skin - the fact that melanin converts 99% of UV received into heat.  This is in sharp contrast to our primary skin perceptions of touch, temperature, and such. 
The same is likely true of HFC.  If we have any sensitivity to them it is likely as a secondary effect, and the notion that the existence of HFC in a "natural environment" necessitates or even implies primary sensory ability is silly.
Creature of habit.

Hypersonic Effect (HFCs etc ...)

Reply #9
There have only been two real research papers published on the entire topic. They are all from Japanese authors. I don't really see any other substantial research published on the topic that supports these claims or rejects them for that matter. Does anyone know of any papers that reject the hypersonic effect? I am sure I can do a search and look into, but in the meantime feel free to share some of the best ones that exist.
budding I.T professional

Hypersonic Effect (HFCs etc ...)

Reply #10
I don't really see any other substantial research published on the topic that supports these claims or rejects them for that matter. Does anyone know of any papers that reject the hypersonic effect? I am sure I can do a search and look into, but in the meantime feel free to share some of the best ones that exist.

The absence of support is all the evidence of rejection one needs.  Short of another paper being presented which confirms the initial claim the only logical conclusion is to not believe in the existence of HFC perception.
Creature of habit.

Hypersonic Effect (HFCs etc ...)

Reply #11
Seems to me the diminution of energy of high-frequency audio signals in air, would be enough to discount the idea that we feel 'ripples' by the time it reaches our skin.  The only truly well-defined 'ultrasonic effect' is transduction via bone, which requires very close proximity to the source.


HF losses in air affect both ends of the recording chain. They are arguably more daunting in the studio and especially the concert hall due to the longer distances involved.

Fact is that our whole audio infrastructure tends to destroy HF signals. Walls don't reflect them well, air attenuates them, microphones tend to ignore them, especially off-axis; and speakers do more damage of the same kind as microphones, only worse.

Then there are the problems of masking and HF response limitations of the ears.

Furthermore, a big chunk of the catalog of music that was released on SACD and DVD-A were sourced from analog tapes with all sorts of inherent HF losses of their own.

It might be true that our skin is somehow sensitive to HF audio, but it is also true that with all of the inherent HF losses in a concert hall or other live venue, we didn't get trained to expect or appreciate them by going to live concerts.

Hypersonic Effect (HFCs etc ...)

Reply #12
Didn't the study actually add artificial HF tones?
Is 24-bit/192kHz good enough for your lo-fi vinyl, or do you need 32/384?

Hypersonic Effect (HFCs etc ...)

Reply #13
I can at least relate my own experience.  In high school physics lab we had some equipment that could put out 30 khz sound wave. I don't know if everyone could tell when it was on, but a lot could. 

Subjectively it was like a desensing of other sounds, similar to a strong out of band signal overloading a radio receiver.  Maybe like having water in  your ears.

Hypersonic Effect (HFCs etc ...)

Reply #14
Were you able to verify that what you experienced was indeed only a pure 30kHz tone and not something like the effect of intermodulation?  Amongst other things, proper scientific method involves validation of the test being conducted.
Is 24-bit/192kHz good enough for your lo-fi vinyl, or do you need 32/384?

Hypersonic Effect (HFCs etc ...)

Reply #15
I imagine there were harmonics.  As far as intermod products within normal hearing range, we wold have heard them, right?  This was just a disruption of hearing, and maybe some tension in those muscles that act as AGC for normal hearing.

Hypersonic Effect (HFCs etc ...)

Reply #16
I take it that you were able to validate that what was hitting people's ears was just a 30 kHz tone using something like a capable microphone and spectrum analyzer?  Without a well-controlled test, the results aren't exactly credible.

But yes, intermod products may have fallen in high end of normal hearing range which could have explained what you believed you and others were experiencing.  I'm sure there are other possibilities.

The idea that a lot of young people in a given sample could detect 30 kHz doesn't correlate well with any of the research I've ever encountered.  Maybe it was something in the water where you guys went to school.
Is 24-bit/192kHz good enough for your lo-fi vinyl, or do you need 32/384?

Hypersonic Effect (HFCs etc ...)

Reply #17
It was just an example.  I take it that you were able to validate that what was hitting people's ears was just a 30 kHz tone using something like a capable microphone and spectrum analyzer?  Without a well-controlled test, the results aren't exactly credible.


30 khz was what we got from measuring a wave with an oscilloscope.  The basic circuit was a feedback loop with a magnetic pickup next to the transducer which fed an amp feeding the transducer.

With such a setup, just visually inspecting a sine wave, it could easily have 10% distortion without being noticed, but the distortion components would be at harmonics, much higher.

Remember, we may have been precocious, but still high school kids bugging people by screwing around with equipment meant for something else.  Not somebody trying to submit a paper to JAES.

But yes, intermod products may have fallen in high end of normal hearing range which could have explained what you believed you and others were experiencing.  I'm sure there are other possibilities.


Intermod would require another constant signal of at least 10 khz to mix the 30K down.  Where would that come from?  Could be some internal oscillation in the electrical circuit, but would have been visible on the scope.

Hypersonic Effect (HFCs etc ...)

Reply #18
It sounds like you have a handle as to what was sent to the transducer, but not what was moving through the air.  This is critically important.
Is 24-bit/192kHz good enough for your lo-fi vinyl, or do you need 32/384?

Hypersonic Effect (HFCs etc ...)

Reply #19
Haven't found the source, but here's some "background info" from an abstract of some paper at pubmed.gov which implies the effects I observed are known:

"Intense airborne ultrasound has been associated with hearing loss, tinnitus, and various nonauditory subjective effects, such as headaches, dizziness, and fullness in the ear."


http://www.ncbi.nlm.nih.gov/sites/entrez?D...$=activity

Hypersonic Effect (HFCs etc ...)

Reply #20
There have only been two real research papers published on the entire topic. They are all from Japanese authors. I don't really see any other substantial research published on the topic that supports these claims or rejects them for that matter. Does anyone know of any papers that reject the hypersonic effect? I am sure I can do a search and look into, but in the meantime feel free to share some of the best ones that exist.


this is getting repetitive, as I posted these on that other thread (both cite Oohashi et al's work):

this is a direct attempt at verification
http://www.aes.org/e-lib/browse.cfm?elib=12375

this is more indirect
http://www.aes.org/e-lib/browse.cfm?elib=13185


Seems to me the diminution of energy of high-frequency audio signals in air, would be enough to discount the idea that we feel 'ripples' by the time it reaches our skin.  The only truly well-defined 'ultrasonic effect' is transduction via bone, which requires very close proximity to the source.

Is this a well understood / studied area?

I mean, isn't that also the case for bats? Surely whatever hits a bat's ear also hits our skin.


But that doesn't mean we are as sensitive to it as bats are....or at all.






I can at least relate my own experience.  In high school physics lab we had some equipment that could put out 30 khz sound wave. I don't know if everyone could tell when it was on, but a lot could. 

Subjectively it was like a desensing of other sounds, similar to a strong out of band signal overloading a radio receiver.  Maybe like having water in  your ears.



Or quite possibly like hearing intermodulation distortion in the accepted 'audible' range, possibly introduced at the loudspeaker, if not before.  A 'scope reading of the tone generator itself won''t tell you that.

.

Haven't found the source, but here's some "background info" from an abstract of some paper at pubmed.gov which implies the effects I observed are known:

"Intense airborne ultrasound has been associated with hearing loss, tinnitus, and various nonauditory subjective effects, such as headaches, dizziness, and fullness in the ear."


http://www.ncbi.nlm.nih.gov/sites/entrez?D...$=activity



Lenhardt is an authority on bone-conducted ultrasound, so he should be taken seriously.  However, I dun him points for citing Oohashi is if it were 'settled' science in that abstract.  Maybe he's more thorough in the body of the paper.  I'll see if I can download this paper from work (I kinda doubt it...it's in a pretty obscure journal).

Hypersonic Effect (HFCs etc ...)

Reply #21
Or quite possibly like hearing intermodulation distortion in the accepted 'audible' range, possibly introduced at the loudspeaker, if not before.  A 'scope reading of the tone generator itself won''t tell you that.


Intermodulation isn't a magic source of signals.  It's a mixing product of 2 or (usually) more signals.  Where would the others come from in sufficient strength?  Distortion of the primary signal doesn't count, because that would be harmonically related. 

And, as I said before, if there was a intermod product in the audible range, it would be.......audible!

Hypersonic Effect (HFCs etc ...)

Reply #22
Intermodulation isn't a magic source of signals.  It's a mixing product of 2 or (usually) more signals.  Where would the others come from in sufficient strength?  Distortion of the primary signal doesn't count, because that would be harmonically related.



What if your loudspeaker is ill-equipped to pass a high-level 30 kHz signal undistorted (or reject it silently)?

You might be interested to read this presentation by
Quote
http://www.davidgriesinger.com/
David Griesinger

Quote
And now for something completely different... Being currently over 60, and having in my youth studied information theory, I have a low tolerance for claims that "high definition" recording is anything but a marketing gimmick. I keep, like the Great Randi, trying to find a way to prove it. Well, I got the idea that maybe some of the presumably positive results on the audibility of frequencies above 18000Hz were due to intermodulation distortion, that would covert energy in the ultrasonic range into sonic frequencies. So I started measuring loudspeakers for distortion of different types - and looking at the HF content of current disks. The result is the paper below, which is a HOOT! Anytime you want a good laugh, take a read. 

Slides from the AES convention in Banff on intermodulation distortion in loudspeakers and its relationship to "high definition" audio.





Quote
And, as I said before, if there was a intermod product in the audible range, it would be.......audible!



At the very highest part of the audible range, the sensation might not be reported as 'heard'.

Hypersonic Effect (HFCs etc ...)

Reply #23
I chose my words carefully, and said nothing about whether HFC has an effect on the human body, simply that we are unlikely to have a primary sensory organ sensitive to its reception.

Yes. We've established that we can't hear ultrasound.

To be pedantic, though, we do not feel UV on our skin, rather we feel the secondary effects of UV radiation on our skin - the fact that melanin converts 99% of UV received into heat.  This is in sharp contrast to our primary skin perceptions of touch, temperature, and such.

No need for pedantry, just some accuracy. I didn't say we "feel UV on our skin", I said "we feel its effect on our skin", thus if its effect (primary, secondary or tertiary) is damage or the conversion of UV into heat, then certainly, that is the effect we feel on our skin.

Soap, you keep making stuff up to shoot it down:
The same is likely true of HFC.  If we have any sensitivity to them it is likely as a secondary effect, and the notion that the existence of HFC in a "natural environment" necessitates or even implies primary sensory ability is silly.

The report never stated that "the existence of HFC in a "natural environment" necessitates or even implies primary sensory ability"; it suggested that it "is premature to conclude that consciously inaudible high-frequency sounds have no effect on the physiological state of listeners". That's very different.



Seems to me the diminution of energy of high-frequency audio signals in air, would be enough to discount the idea that we feel 'ripples' by the time it reaches our skin.  The only truly well-defined 'ultrasonic effect' is transduction via bone, which requires very close proximity to the source.

Is this a well understood / studied area?

I mean, isn't that also the case for bats? Surely whatever hits a bat's ear also hits our skin.


But that doesn't mean we are as sensitive to it as bats are....or at all.

I never suggested that we are as sensitive to HFCs as bats, I simply said that what reaches a bat, reaches a human. However, we don't seem to know whether or not we are completely insensitive to HFCs. I think it would be interesting to find out if we are or not, and if we are, to what degree and what is the effect.

Surely it must be possible to conduct proper research on this:

Fire some HFCs at people in a controlled environment and measure brain activity?
I'm pretty certain that a) all this stuff is inaudible and b) we don't consciously register the "feeling" of HFCs hitting our skin. However, I believe that HFCs may have an effect on us and the fact that we're talking about it, suggests it's more controversial than the idea that things fall to the ground instead of falling skyward. It would be nice to get to the point where such controversy no longer exists.

C.

[EDIT: Typo]
PC = TAK + LossyWAV  ::  Portable = Opus (130)

Hypersonic Effect (HFCs etc ...)

Reply #24
(over quote limit?)
I was not attempting to disagree with your stated position so much as the logic behind the quoted passage regarding tropical rainforests.

To be pedantic, though, we do not feel UV on our skin, rather we feel the secondary effects of UV radiation on our skin - the fact that melanin converts 99% of UV received into heat.  This is in sharp contrast to our primary skin perceptions of touch, temperature, and such.

No need for pedantry, just some accuracy. I didn't say we "feel UV on our skin", I said "we feel its effect on our skin", thus if its effect (primary, secondary or tertiary) is damage or the conversion of UV into heat, then certainly, that is the effect we feel on our skin.
  Misread on my part - I apologize.
Soap, you keep making stuff up to shoot it down:

The same is likely true of HFC.  If we have any sensitivity to them it is likely as a secondary effect, and the notion that the existence of HFC in a "natural environment" necessitates or even implies primary sensory ability is silly.

The report never stated that "the existence of HFC in a "natural environment" necessitates or even implies primary sensory ability"; it suggested that it "is premature to conclude that consciously inaudible high-frequency sounds have no effect on the physiological state of listeners". That's very different.

Almost all I have written is in response to this:

Quote
From an anthropogenetic point of view, the sensory system of human beings exposed to a natural environment would stand a good chance of developing some physiological sensitivity to HFCs. It is premature to conclude that consciously inaudible high-frequency sounds have no effect on the physiological state of listeners.
It appears to me to be claiming sensory perception by another name.  How is "physiological sensitivity" developed in response to environmental information content not a sense?  Is it not a sense because they speculate it might be subconscious? 

My argument is hardly the straw man you accuse it of being.  Disagree with my word choice over "primary" and I can't cite you.
Creature of habit.

 
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