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.

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

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

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.

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.

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.

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.

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.

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.

Quote from: krabapple on 2009-01-02 06:59:40

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.

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.

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

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.

http://www.davidgriesinger.com/

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.

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

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.

Quote from: carpman on 2009-01-02 08:10:32

Quote from: krabapple on 2009-01-02 06:59:40

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.

Quote from: Soap on 2009-01-02 12:42:50

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:

Quote from: Soap on 2009-01-02 12:42:50

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.

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.