Thread: Hypersonic effect: Inaudible High-Frequency Sounds Affect Brain Activity

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Post by canonical May 24, 2009 (1 of 37)
SACD can reproduce frequencies dramatically higher than CDs (up to 20kHz).

I've seen several postings here that state that high-frequencies don't matter because human hearing tapers off anyway within the CD threshold.
Most recently, fafnir wrote:

> Lastly, and somewhat off topic, those who claim 20 kHz as the upper frequency cut off for adult
> hearing are living in a dream world. You're very fortunate if you are over 40 and your hearing at 15 kHz isn't in the mud.

Even though one may not be able to 'hear' the high-frequency sounds, those high-frequency sounds still effect the music we do hear (through harmonics), and via our bodies. The latter is known as the "hypersonic effect", and was double-blind tested and found to be significant in:

Oohashi et al (2000), Journal of Neurophysiology,vol 83(6), pp. 3548-3558
Inaudible High-Frequency Sounds Affect Brain Activity: Hypersonic Effect

http://jn.physiology.org/cgi/content/full/83/6/3548

Even though the subjects in the study could not actually hear the high-frequency sound when it was presented alone:

1. EEG monitoring of their brain activity showed statistically significant enhancement in alpha-wave activity when the high-frequency components were included, and

2. The subjects in the study found the sound containing the high-frequency components to be more pleasant than the same sound lacking the high-frequencies.

Most interesting, I think.

Post by mahlerei May 24, 2009 (2 of 37)
canonical said:

SACD can reproduce frequencies dramatically higher than CDs (up to 20kHz).

I've seen several postings here that state that high-frequencies don't matter because human hearing tapers off anyway within the CD threshold.
Most recently, fafnir wrote:

> Lastly, and somewhat off topic, those who claim 20 kHz as the upper frequency cut off for adult
> hearing are living in a dream world. You're very fortunate if you are over 40 and your hearing at 15 kHz isn't in the mud.

Even though one may not be able to 'hear' the high-frequency sounds, those high-frequency sounds still effect the music we do hear (through harmonics), and via our bodies. The latter is known as the "hypersonic effect", and was double-blind tested and found to be significant in:

Oohashi et al (2000), Journal of Neurophysiology,vol 83(6), pp. 3548-3558
Inaudible High-Frequency Sounds Affect Brain Activity: Hypersonic Effect

http://jn.physiology.org/cgi/content/full/83/6/3548

Even though the subjects in the study could not actually hear the high-frequency sound when it was presented alone:

1. EEG monitoring of their brain activity showed statistically significant enhancement in alpha-wave activity when the high-frequency components were included, and

2. The subjects in the study found the sound containing the high-frequency components to be more pleasant than the same sound lacking the high-frequencies.

Most interesting, I think.

Yes, but that's only half the story. As I pointed out in my post on the BIS thread these results are gleaned from live performances. It's not impossible to replicate in a recording but it's a lot more difficult and depends on a variety of factors.

An interesting topic but please don't skew it before it even gets off the ground.

Post by raffells May 24, 2009 (3 of 37)
canonical said:

Most interesting, I think.

Yes this has been raised many times over quite a few years and it is the work of profesionals.
Please note I last raised it on thread 501 on the great Bissie revelation debate.
The real problem here (pun) is the amatuer approach made by some people who make postings.They have opinions but dont make the effort to find out from experts..
The year 2000 report is not really new but just another set of tests and much earlier results are easy to obtain.Even now there are probably people looking into gene related issues to why people have different qualities of hearing.

I could post other links to specialist reports in the hearing field and they reveal a number of facts about listeners .None of these have changed much in 30 plus years that I know about , except possibly one..This is the unnatural effect of digitally recorded sonics..Distortion being the inverse of natural sound historically..yes its the reason we have dither on digitals low level signals...It was the subject in a hifi technical review approx 1982?
.Amazingly different people have different hearing skills. There are even a number of known reasons for these differences. There are even differences of opinions as to the known reasons but what would you expect.
I do feel it is a waste of time (and have for years) trying to convince anyone to go and find out the facts.
The one posetive thing that comes out of the postings is of interest to me.When I see posting that they cannot hear much difference in different sample rates or the effect of jitter is over rated and one other well known comment,then I know to ignore this persons opinions as to what represents top fidelity sound..Julien is quite safe on this one..


Dave

Post by canonical May 24, 2009 (4 of 37)
mahlerei said:

Yes, but that's only half the story. As I said in my post these results are gleaned from live performances.

???

The paper clearly states that *recordings* of gamelan music were used. The paper says:

==

Traditional gamelan music of Bali Island, Indonesia, a natural sound source containing the richest amount of high frequencies with a conspicuously fluctuating structure, was chosen as the sound source for all experiments. A traditional gamelan composition, "Gambang Kuta," played by "Gunung Jati," an internationally recognized gamelan ensemble from Bali, was recorded using a B&K 4135 microphone, a B&K 2633 microphone preamplifier, and a B&K 2804 power supplier, all manufactured by Brüel and Kjær (Nærum, Denmark). The signals were digitally coded by Y. Yamasaki's high-speed one-bit coding signal processor (United States Patent No. 5351048) (Yamasaki 1991) with an A/D sampling frequency of 1.92 MHz and stored in a DRU-8 digital data recorder (Yamaha, Hamamatsu, Japan). This system has a generally flat frequency response of over 100 kHz.

==

They then truncated the frequency distribution at 22 kHz to generate sound without the high-frequency components, which is basically what the CD format does.

Post by Kal Rubinson May 24, 2009 (5 of 37)
canonical said:

???

The paper clearly states that *recordings* of gamelan music were used. The paper says:

==

Traditional gamelan music of Bali Island, Indonesia, a natural sound source containing the richest amount of high frequencies with a conspicuously fluctuating structure, was chosen as the sound source for all experiments. A traditional gamelan composition, "Gambang Kuta," played by "Gunung Jati," an internationally recognized gamelan ensemble from Bali, was recorded using a B&K 4135 microphone, a B&K 2633 microphone preamplifier, and a B&K 2804 power supplier, all manufactured by Brüel and Kjær (Nærum, Denmark). The signals were digitally coded by Y. Yamasaki's high-speed one-bit coding signal processor (United States Patent No. 5351048) (Yamasaki 1991) with an A/D sampling frequency of 1.92 MHz and stored in a DRU-8 digital data recorder (Yamaha, Hamamatsu, Japan). This system has a generally flat frequency response of over 100 kHz.

==

They then truncated the frequency distribution at 22 kHz to generate sound without the high-frequency components, which is basically what the CD format does.

None of Oohashi's papers have been replicated or confirmed by any other lab. In addition, there have been many criticisms of his methods and extracted conclusions. Provocative, nonetheless.

Kal

Post by rammiepie May 24, 2009 (6 of 37)
Even though our hearing (at various stages in our lives) may never be perfect, the high frequencies associated with superb analogue gear and SACDs can certainly be "detected" in an airiness of instrumental timbres, which if not present, would collapse the illusion that we are hearing something very special. To make an analogy, I recently put a Meridian MF1S projector in my home theater and I am seeing colors that I never thought were possible on a home video component (Even my 52" Sharp Aquos on the same source material can't come close). More will always be more and that is why we, here, at SA-CD net appreciate the "more" of a properly recorded DSD-mastered SACD [provided, also, that our equipment chain is up to the task].

Post by fafnir May 24, 2009 (7 of 37)
Kal Rubinson said:

None of Oohashi's papers have been replicated or confirmed by any other lab. In addition, there have been many criticisms of his methods and extracted conclusions. Provocative, nonetheless.

Kal

As chance would have it, my 12 year old grandson together with his parents visited my wife and I today. He came complete with an i-touch thingy that can communicate over our wireless network and perform other wondrous tasks in which I have no interest. More to the point, he brought up an applet that apparently acts as a variable frequency oscillator, playing tones up to 20 KHz.

I couldn't resist the opportunity to test the hearing of one and all. Needless to say, no one, including our grandson, could hear the 20 KHz tone - 17.5 was the best he could manage. Our son-in-law and daughter kicked in a about 15 KHz with my wife and I around 10. There were no surprises hear (sic). Not a soul detected any sound subliminally that could not otherwise actually be heard. I know that this is not much of test, but is interesting nonetheless. Actually hearing 20 KHz with your ears, not though your brain or anywhere else is just about impossible, just as I stated in another thread.

I think that Bissie's test in which his engineers and musicians could detect no improvement in DSD as opposed to PCM remains extremely convincing.

Post by sunnydaler May 24, 2009 (8 of 37)
http://www.jetcityorange.com/mosquito-ringtone/mosquito-ringtone.wav
This is a 17KHz tone.
http://www.jetcityorange.com/dog-whistle/
Here's dog whistles. 16KHz~48KHz tones.

17KHz tone is pretty audible to me even in low volume. 20KHz tone came close to the limit of my hearing ability. But it's still audible clearly. :) (I am 26 years old.) I think many people can hear higher frequency above 20kHz.

http://www.tucows.com/preview/240287
Here's a test tone generator. It's an evaluation version.(for constant pure tone, select 'sine' wave function and uncheck amplitude modulation box)

Post by rammiepie May 24, 2009 (9 of 37)
fafnir said:

As chance would have it, my 12 year old grandson together with his parents visited my wife and I today. He came complete with an i-touch thingy that can communicate over our wireless network and perform other wondrous tasks in which I have no interest. More to the point, he brought up an applet that apparently acts as a variable frequency oscillator, playing tones up to 20 KHz.

I couldn't resist the opportunity to test the hearing of one and all. Needless to say, no one, including our grandson, could hear the 20 KHz tone - 17.5 was the best he could manage. Our son-in-law and daughter kicked in a about 15 KHz with my wife and I around 10. There were no surprises hear (sic). Not a soul detected any sound subliminally that could not otherwise actually be heard. I know that this is not much of test, but is interesting nonetheless. Actually hearing 20 KHz with your ears, not though your brain or anywhere else is just about impossible, just as I stated in another thread.

I think that Bissie's test in which his engineers and musicians could detect no improvement in DSD as opposed to PCM remains extremely convincing.

RBCD theoretically runs the gamut from 0-20,000....which means the bass would be below any subs capacity and the higher echelon would satisfy all the golden ears in the universe. But that just ain't so. As for the DSD vs. PCM controversy, I think Bissie's findings are accurate since one would imagine BIS is using state of the art equipment in both formats, using similar mike set-ups, etc., and I, personally, never had any complaints with 96/24, provided one has state of the art equipment in their listening room to replicate it. And let's be real. For the time being until SACD stereo/multi can be downloaded at a VERY reasonable price, most large companies will continue to use PCM with these very accessible downloads in mind! Even Sony had to abandon DSD when introducing Blu-Ray because as I've stated before on this site, ALL motion picture soundtracks utilize PCM in their recording, mixing and mastering chains.It's not what WE want, it's really what the recording companies are willing to give us and the economic reality is, for the moment, PCM IS king!

Post by Lee Scoggins May 24, 2009 (10 of 37)
Life above 20khz:

http://www.cco.caltech.edu/~boyk/spectra/spectra.htm

Case closed. DSD still rules.

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