Evidence for the Hypersonic Effect
Mar 27, 2006 at 10:51 PM Thread Starter Post #1 of 7

Omega

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There's a lot of debate about whether or not we can perceive audio information encoded at frquencies higher than our ears can perceive. Without entering that argument per se, I recently ran across an interesting article arguing that we can in fact perceive this information, and thought it was interesting enough to pass on to you all
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Oohashi et al. Journal of Neurophysiology (2000) 83(6):3548-3558.
Link to article (may require access persmission)

In brief, the authors addressed the issue of a subject being unable to consciously identify an effect of high-frequency sound by using quantifiable and reproducible measurements of brain activity (EEG=electroencephalography, PET=positron emission tomography, and a comparison of high-frequency sound with full range sound).

"In conclusion, our findings that showed an incrase in alpha-EEG potentials, activation of deep-seated brain structures, a correlation between alpha-EEG and rCBF (ed. tissue activity correlates with rCBF measurement) in the thalamus and a sunjective preference toward the FRS (full range sound), give strong evidence supporting the existence of a previously unrecognized response to high-frequency sound beyond the audible range that might be distinct from more usual auditory phenomena."
 
Mar 28, 2006 at 12:45 AM Post #2 of 7

blip

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I always knew it... Time to get me a frickin' super-tweeter. (maybe plasma!) 50Khz here we come!
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Seriously, good to know.
 
Mar 28, 2006 at 7:15 AM Post #5 of 7

fewtch

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Quote:

Originally Posted by 003
So I should go run out and buy an HE90, over 100KHz frequency response.


Not if you're just listening to redbook CD (22.05 KHz maximum). Even LPs don't typically go over 20 KHz or so, despite their ability to improve on CDs to some degree in this department.

P.S. the rated frequency response is probably how high the headphones go while remaining relatively flat in response. Most headphones will respond to well over 20 KHz to some degree or another.
 
Mar 28, 2006 at 9:12 AM Post #7 of 7

fewtch

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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 HFCs. It is premature to conclude that consciously inaudible high-frequency sounds have no effect on the physiological state of listeners.


Yup, makes sense to me (and it makes the objectivist "humans can't hear that high, so it makes no difference" viewpoint look as limited as it is). It's significant that they used real music too, not short samples. Good article/study, thanks for posting about it.
 

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