Inaudible High-Frequency Sounds Affect Brain Activity: Hypersonic Effect

[Mike_TX]

RE:

Inaudible High-Frequency Sounds Affect Brain Activity: Hypersonic Effect

- Oohashi et al. 2000 J Neurophysiol
Link

This was posted on AVS and I thought it was interesting for discussion at the TCA forum:
Link
The range of human hearing is higher than commonly reported, at least in terms of seeing a change in the brains of people hearing ultrasonics:

http://www.ocf.berkeley.edu/~ashon/a...ltrasonics.htm

"Recent work by Tsutomu Oohashi et al., published in June of 2000 in the Journal of Neurophysiology, shows that the brain may in fact be registering over-20 (or 22) kHz spectral energy. Titled "Inaudible High-Frequency Sounds Affect Brain Activity: Hypersonic Effect", their paper discusses their finding that sounds containing High Frequency Components (HFCs) above the audible range significantly affect the brain activity of listeners."

This is measured, and peer-reviewed. It turns out the 20 kHz limit was incorrectly arrived at in the first place! Think what that means. For one thing, it means that every CD ever made is cutting off frequencies too early, and that listeners who complain that CDs "don't sound right" and are "fatiguing" and feel like there's a "plate of glass" in the way could be making legitimate complaints even though they can't articulate exactly what the problem is.

All those claims about how all we need is 20 kHz and a brick-wall filter, all those self-righteous dismissals based on sampling theory, all of that was based on an original sin. They. Set. The. Cutoff. Too. Low.

It also means SACD is the only source available to end users that preserves ultrasonics. And it explains why SACDs sound better than CDs.

And it also means that receivers that cut off at 20 kHz are damaging the signal.

So rejoice that the SE has better DACs with better internal clocks, because they're needed. (Note that the SE's stereo analog out goes to 96 kHz.)
----------------------------------------------------------------

Here is the abstract:
Tsutomi Oohashi, Emi Nishina, Norie Kawai, Yo****aka Fuwamoto, Hiroshi Imai, "High-Frequency Sound Above theAudible Range Affects Brain Electric Activity and Sound Perception. Audio Engineering Society preprint No. 3207 (91st convention, New York City)". Abstract, page 2. http://jn.physiology.org/cgi/content/abstract/83/6/3548


The full (2000) journal article is posted above.

I have yet to dig into the manuscript, but thought this would be a fun discussion.

A few quotes from the abstract:
- "None of the subjects recognized the [high-frequence components] HFC as sound when it was presented alone
- "Psychological evaluation indicated that the subjects felt the sound contained an HFC to be more pleasant than the same sound lacking an HFC. These results suggest the existence of a previously recognized response to complex sound containing particular types of high frequencies above the audible range. We term this phenomenon the "hypersonic effect."


Mike

PS - PDF size limit doesn't allow loading PDF

[m-fine]

It is an interesting theory, but keep in mind that accurate playback of very high frequencies does not just mean SACD or more likely Blu-ray audio or FLAC's with higher sampling rates.

To capture the content, the recording would need to me made with wider range microphones, captured with a high frequency capable device, stored and mixed on HFC capable systems, and recorded to the media with the HFC, not only intact, but also properly mixed and in balance etc.

Then once you have a recording in hand with all the data, you need a player, DAC, pre-amp, amp and a pair of speakers to handle it. Even worse, you also need a room that preserves the correct balance. Higher frequencies roll off in normal air much faster than low frequencies. As you go up in frequency over 20 khz it will eventually matter if you are sitting 2 meters from your speakers or 4. The HFC content would need EQ applied to get the levels correct for your seating distance. (Note THX already includes a normal "high freq" adjustment to reflect that home theaters are on a smaller scale than full size theaters because of the distance effect on rolloff)

[Mike_TX]

Good points.
You need decent recording and processing throughout the entire audio chain.

I haven't read the full article as people came over last night, but on p. 3549 of Methods section...

Electronics:
"This system has a generally flat frequency resposne of over 100 kHz."

Speakers:
"The speaker system was designed by one of the authors (T. Oohashi) and manufactured by Pioneer Co., Ltd. (Tokyo, Japan). This sound reproduction system had a flat frequency response of over 100 kHz."


Still reading later today...

Mike

[Mike_TX]

Links

Discussion thread that started in the Oppo SE thread at AVS moved to here:

AVS - 48 KHz vs 96 KHz

Other links:
http://www.ocf.berkeley.edu/~ashon/a...ltrasonics.htm
http://en.wikipedia.org/wiki/Hypersonic_effect
http://www.physics.sc.edu/kunchur/Acoustics-papers.htm
http://www.sciencedirect.com/science...222c2a065c25aahttp://www.davidgriesinger.com/intermod.ppt

Kunchur papers

http://www.physics.sc.edu/kunchur/Acoustics-papers.htm

http://www.physics.sc.edu/kunchur/papers/FAQs.pdf

Hydrogen Audio thread on Kunchur papers

Kal Rubinson (of Stereophile) observations about the Oohashi papers here and here.


Like I said, interesting, but 10 years (nearly) old and without (much) replication or impact in the field (either science or products).
:scratchchin:

Mike

[Mike_TX]

online hearing test link

I found this online hearing test posted on the Seaton Sound forum (link) and thought it was interesting/fun:

http://audiocheck.net/audiotests_frequencycheckhigh.php

I heard ~17 kHz with overhead Russound in room speakers.
I may want to test on some other speakers as well...


Mike

PS - Note comments about sound card, etc. in link