[TF1216]

I am struggling to wrap my head around the need for a FIR or IIR filter inside a DAC.  I understand that there are artifacts, as low as 24.1 kHz when sampling at 44.1 kHz, from the 20 kHz image but it's inaudible to us humans.  Discussion then starts up regarding the pros and cons of different filter methodologies like phase-linear, minimum phase, roll-off, ringing, etc.  Why not just skip the filter?

[mark funk]

Well it is audible to your HiFi. Your speakers don't like to have all that high end shit comming there way and your amp does not like to try to play that kind of hash.



                                                                                           

[TF1216]

Thank you for replying Mark.  What about DSD recordings and it's energy above 30 kHz?  Are those frequencies not affecting our equipment because of filters?

[Steve]

When music is playing, harmonics etc above 20khz are registered in the brain. A Japanese test used both EEG and PET scans to measure/demonstrate such. Now if nothing is playing, any ultra-sonics did not appear to register in the brain, as  measured by the EEG, PET.

At least two studies have been performed, one taking 5 years to complete, in which it was demonstrated the
ear could detect 5us (microsecond) changes, while the other study, back in the 80s, demonstrated 2us, from
what Jneutron stated. So "rise time", commonly called "attack time" does make a difference.

Cheers.

[FullRangeMan]

I am struggling to wrap my head around the need for a FIR or IIR filter inside a DAC.  I understand that there are artifacts, as low as 24.1 kHz when sampling at 44.1 kHz, from the 20 kHz image but it's inaudible to us humans.  Discussion then starts up regarding the pros and cons of different filter methodologies like phase-linear, minimum phase, roll-off, ringing, etc.  Why not just skip the filter?

Nice idea indeed. In the vintage Yamaha CDX-2000 it had a knob to turn off the output filter.

We are paying for a output filter why Philips say we need that filter.

[Ethan Winer]

Why not just skip the filter?

It's true that we cannot hear, or otherwise perceive, ultrasonic sounds. But the output filter in a D/A is still needed to prevent aliasing. Aliasing is not unlike IM distortion because it creates sum and difference frequencies in the audible range.

As for the Oohashi tests that claimed to prove we can hear ultrasonic content, that was debunked a few years later by another group of researchers who traced the problem to those same sum and difference frequencies caused by IM distortion in the tweeter. The text below is from my Audio Expert book.

--Ethan

There was also a study by Tsutomu Oohashi that’s often cited by audiophiles as proof that we can hear or otherwise perceive ultrasonic content. The problem with this study is they used one loudspeaker to play many high-frequency components at once, so IM distortion in the tweeters created difference frequencies within the audible range. When the Oohashi experiment was repeated by Shogo Kiryu and Kaoru Ashihara using six separate speakers, none of the test subjects were able to distinguish the ultrasonic content. This is from their summary:

"When the stimulus was divided into six bands of frequencies and presented through six loudspeakers in order to reduce intermodulation distortions, no subject could detect any ultrasounds. It was concluded that addition of ultrasounds might affect sound impression by means of some nonlinear interaction that might occur in the loudspeakers."

[Steve]

As for the Oohashi tests that claimed to prove we can hear ultrasonic content, that was debunked a few years later by another group of researchers who traced the problem to those same sum and difference frequencies caused by IM distortion in the tweeter. The text below is from my Audio Expert book.

--Ethan

There was also a study by Tsutomu Oohashi that’s often cited by audiophiles as proof that we can hear or otherwise perceive ultrasonic content. The problem with this study is they used one loudspeaker to play many high-frequency components at once, so IM distortion in the tweeters created difference frequencies within the audible range. When the Oohashi experiment was repeated by Shogo Kiryu and Kaoru Ashihara using six separate speakers, none of the test subjects were able to distinguish the ultrasonic content. This is from their summary:

"When the stimulus was divided into six bands of frequencies and presented through six loudspeakers in order to reduce intermodulation distortions, no subject could detect any ultrasounds. It was concluded that addition of ultrasounds might affect sound impression by means of some nonlinear interaction that might occur in the loudspeakers."

I have to respectfully disagree for several reasons, which we will find to be in
contradiction to your mentioned study by Shogo Kiryu and Kaoru Ashihara .

First, the study I mention was performed by Oohashi, Nishini, Honda, Yonekura, Fuwamoto,
Kawai, Maekawa, Nakamura, Fukuyama and Shibasaki. Their article was presented in
"Journal of Neurphysiology" for those interested.

1) The first thing I noticed was no scientific conclusion was presented in the Shogo Kiryu and Kaoru Ashihara
paper.

It was concluded that addition of ultrasounds might affect sound impression by means of some nonlinear
interaction that might occur in the loudspeakers.

Might" is speculation. There is no solid conclusion to their "experiment" which will be contradicted below.
So where are the actual measurements from the study? 

2)

"It was concluded that addition of ultrasounds might affect sound impression by means of some nonlinear
interaction that might occur in the loudspeakers." 

and

The problem with this study is they used one loudspeaker to play many high-frequency components at once,
so IM distortion in the tweeters created difference frequencies within the audible range.

One loudspeaker was not used for all frequencies including ultra-high, but a separate ultrahigh dome diamond tweeter.
Extremely high slope filters were used to prevent ultra highs and lows from mixing.
When only ultra-high frequency information was presented, no brain activity was
perceived by the PET or EEG scans. And the medical experts that were consulted and assisted, and the peer reviewers did not have any problems. Besides that, there are still risetime changes which have been demonstrated to be relavent,
which will be address in point three.

3) When ultra-high frequencies are introduced to "regular" music, the rise time (commonly called "attack time")
changes. At least two studies, one presented/posted by Jneutron, and one myself (Dr. Kunchur) demonstrated
that 2us and 5us (us = microseconds) respectively are identified by the human ear. Not both ears but each ear.
Dr. Kunchur's work has been presented to a variety of specialities, Scientists, Electronics,
University, and National medical organizations etc, besides being peer reviewed.
 
Thus not only does Shogo Kiryu and Kaoru Ashihara Not provide measureable proof, but their speculations are contradictory to the expertise of the medical community in at least two ways.
First, the medically approved measureable evidence provided by Oohashi, Nishini, Honda, Yonekura, Fuwamoto, Kawai, Maekawa, Nakamura, Fukuyama and Shibasaki.
Secondly, the medically approved conclusions Dr. Kunchur's work and Jneutron's source from the early 80s.
It is obvious that Kiryu and Ashihara's work is insufficient, very limited. 
 
Dr. Kunchur's addresses include, just a few mentioned:

Acoustical Society of America (ASA)
Association of Research in Otolaryngology (ARO)
American Physical Society (APS).
colloquium at Fergusson College, Physics Department, on Dec. 11, 2010.

public lecture at Science Cafe organized by EngenuitySC, on March 9, 2010.
Audio Engineering Guest Lecture given in the USC Dept. of Electrical Engineering, Columbia, Feb. 2, 2010.
seminar at University of Georgia, on October 8, 2009.
Music Composition Seminar given at USC School of Music, on January 30, 2009.
colloquium at Indira Gandhi Center for Atomic Research, on December 23, 2008.

seminar given at Argonne National Laboratory, on April 15, 2008.
colloquium given at Northern Illinois University, on April 18, 2008. (Teach hard of hearing there.)
colloquium given at Oak Ridge National Laboratory, on August 21, 2007.
colloquium given at Bhabha Atomic Research Centre on December 18, 2006.

institute-wide ASET (Advances in Science, Engineering, and Technology) colloquium given at Tata Institute of Fundamental Research (TIFR) on December 22, 2006.
seminar given at Department of Biomedical Engineering, University of California, Irvine, March 22, 2005.

colloquium given at University of South Carolina, September 22, 2005.
Guest lecturer at the Columbia Student Chapter of the Audio Engineering Society (AES).
Iowa State University, Ames, December 6, 2004.
University of Georgia, Athens, October 14, 2004.
Tata Institute of Fundamental Research, Mumbai, August 11, 2004.
Bhabha Atomic Research Centre, Mumbai, August 9, 2004.
Music perception and reproduction — time is not always one over frequency, Rutgers University, Physics colloquium, October 29, 2003
The Science of Hearing, Music Preception and Music Reproduction, University of South Carolina, Department of Physics and Astronomy, March 20, 2003.

Addressing these venues covers all the vital aspects of the paper Dr. Kunchur prepared as they cover the national medical, electronics, physics etc. The rigors of the paper are immense as is presented near the bottom.

Adding ultrasonics, even just above 20khz, easily changes the rise time required to be perceived, let alone higher still.

Here is a description of how a well performed experiment is published, from start to finish.
Dr. Kunchur explains the rigors of what a truly scientific paper involves.

"For those who have no idea what science and the (incredibly rigorous) scientific process is,
let me explain what went into publishing the two above mentioned papers that have apparently
 generated controversy among lay readers (but no controversy whatsoever in all the professional
circles, which include audiolists, otolaryngologists, acousticians, engineers, and physicists ).
 
An experiment has to be carefully thought out and then submitted as a proposal to an
Institutional Review Board (IRB) and approved by them before it can even begin. Then optimum equipment,
methods, and a multitude of cross checks has to be developed (if you read my papers in their entirety,
you will appreciated what went in).

The results, analysis, and conclusions are then carefully considered
and discussed with colleagues who are experts in their related interdiscplinary fields; for this I went in
person to various universities and research institutes and met with people in departments of
physics, engineering, psychology, neuroscience, music,
communications sciences, physiology, and materials science.
 
After that the results and conclusions were presented at conferences of the
Acoustical Society of America (ASA),
Association of Research in Otolaryngology (ARO), and
American Physical Society (APS).

Seminars were also made at numerous universities and research/industrial institutions
(please see the list on my web site). After each presentation, the audience is free to tear
apart the conclusions and ask all possible questions. Eminent people such as presidents
of the above mentioned societies and corporations (ASA, ARO, Bose corporation, etc.)
have been present during my presentations.
 
After passing through this grueling oral presentation process, written manuscripts were then
submitted to journals. There, anonymous referees are free to attack the submission in any way they want.
More than a dozen referees and editors have been involved in this journal refereeing process.
Only after everyone is satisfied with the accuracy of the results and all statements made in the manuscript,
are the papers published in the journals. The entire process took around 5 years from initial concept to refereed publications."

Adding the ultrasonics easily changes the rise time by many times the 5us required to be perceived, and even greater if 2us, as Jneutron posted concerning a study. Yet your study claims not.


>So academia, national organizations, electronics, medical fields (where the actual research is performed) were heavily involved in Dr. Kunchur's work, just as in Oohashi, Nishini, Honda, Yonekura, Fuwamoto,
Kawai, Maekawa, Nakamura, Fukuyama and Shibasaki's experiment/work. And both contradict the Shogo Kiryu and Kaoru Ashihara study.
 
One has to be careful not to get caught up in industry attempts, as some on Stereophile's forum witnessed in the distant past, who were pushing redbook standard by using the Shogo Kiryu and Kaoru Ashihara paper. Industry has a vested interest when money is involved, especially saving money. One has to be careful of one's sources.

Cheers.

[Ethan Winer]

"Might" is speculation. There is no solid conclusion to their "experiment" which will be contradicted below.

I think this is perfectly clear:

"When the stimulus was divided into six bands of frequencies and presented through six loudspeakers in order to reduce intermodulation distortions, no subject could detect any ultrasounds."

One loudspeaker was not used for all frequencies including ultra-high, but a separate ultrahigh dome diamond tweeter. Extremely high slope filters were used to prevent ultra highs and lows from mixing.

Sure, but the problem is IM difference frequencies between the ultrasonic frequencies. If you mix 60 KHz and 65 KHz nonlinearly, you get a 5 KHz difference tone which is audible. So segregating the in-band content from the ultrasonic content is not enough to avoid those artifacts.

Dr. Kunchur's work has been presented to a variety of specialities, Scientists, Electronics,
University, and National medical organizations etc, besides being peer reviewed.

That's a very different issue, but Kunchur's work has been called into question (to put it kindly) by people a lot more knowledgeable than me:

http://www.hydrogenaudio.org/forums/index.php?showtopic=73598

Whether people can hear, or otherwise perceive, ultrasonic content has been researched many times over the years, and I'm not aware of any credible evidence showing that it's audible.

--Ethan

[Steve]

author=Ethan Winer link=topic=111949.msg1160773#msg1160773 date=1354295849]
I think this is perfectly clear:

"When the stimulus was divided into six bands of frequencies and presented through six loudspeakers
in order to reduce intermodulation distortions, no subject could detect any ultrasounds."

1) I see no measurements, just speculation. Will you present the data and how the data was
arrived at or is it too weak. 
In my previous post, I had no reservations posting/listing the massive medical backup, from at least
three national medical organizations, plus electronics, electrical engineering, universities, physics etc,
who actually do the research. In otherwards, mainstream science. See the next comments explaining
more.

Sure, but the problem is IM difference frequencies between the ultrasonic frequencies. If you mix 60 KHz
and 65 KHz nonlinearly, you get a 5 KHz difference tone which is audible. So segregating the in-band
content from the ultrasonic content is not enough to avoid those artifacts.

Remember, when the ultrasonics were presented, there was no detection of brain activity by the
PET or EEG scans. So their and your speculative conclusions have no basis in fact.

That's a very different issue, but Kunchur's work has been called into question (to put it kindly) by people
a lot more knowledgeable than me:

http://www.hydrogenaudio.org/forums/index.php?showtopic=73598

Interesting. Here is what Dr. Kunchur stated.

For those who have no idea what science and the (incredibly rigorous) scientific process is, let me explain what went into publishing the two above mentioned papers that have apparently generated controversy among lay readers (but no controversy whatsoever in all the professional circles, which include audiolists, otolaryngologists, acousticians, engineers, and physicists ).

 
So those in the string claim that the ones who actually perform the research, academia
from universities have little idea what they are doing. Not surprising since
Tobacco also used this same tatic for decades. Politics, legalities hindered
saving lives.

It is not a problem since members appears to be industry based 
 individuals and marketers, who wish to limit the bandwidth and thus
expense. One on the string even won a national IEEE award and was
commended because, he managed to reduce the bit rate by 90%
while not seriously degrading the music quality. Seems reducing
costs relates to winning awards from industry.
 
So it is not surprising that they would attack with a vengeance Dr. Kunchur,
Oohashi, Nishini etc., and multiple national mainstream medical organizations dealing with hearing,
multiple main stream academia, engineers, physicists, peer reviewers,
main stream science since they were heavily involved and supportive of
Dr. Kunchur's work for some 5 years.

This is important as we cannot afford to have science up for sale.
Either we have a trustworthy and honest main stream science or science
goes to the highest bidder, which would be industry. That is not in the public's interest.

On the other hand I don't see any audio companies associated with Dr. Kunchur and Oohashi, Nishini, Honda's work.
 
Secondly, at least two members who have posted in that string
have been witnessed on other forums (Stereophile, AVS etc) altering Dr. Kunchur's work/conclusion   
and Oohashi, Nishini etc PET/EEG measurements, and claiming the tests were flawed. Both
eventually admitted they presented false information. That raises the question of ethics.

One claimed headphones were used, and claimed bone conduction for the measurements,
when in fact super tweeters were used, 8 feet from the subjects.

The other, X, claimed that all one has to do is signal delay 5us from one ear vs the other ear.
Of course, under such a test, ultra sonics was not necessary.
However, that was not what Dr. Kunchur's paper demonstrated. In fact,
Dr. Kunchur's paper demonstrated, and concluded that a 5us timing change for each ear,
independent of the other ear, was perceived; which does require ultra sonic information to be available.
Xs discredited Dr. Kunchur for 28 page until the confrontation was too strong and admitted guilt.
So I would be suspicious of those who attack main stream medicine and science, especially on forums.

Whether people can hear, or otherwise perceive, ultrasonic content has been researched many times
over the years, and I'm not aware of any credible evidence showing that it's audible.

So there is no credible evidence in main stream science, three national medical organizations who perform the research and obtain data, multiple academia etc, all who worked with and supports Dr. Kunchur's work/paper that 5us time change is perceived by the ear. And of course Jneutron's recall of a study of 2us is also not credible.

In conclusion it is clear, once again, that Shogo Kiryu and Kaoru Ashihara's work still contradicts main stream science, and the fact that 5us time changes are perceived, which requires the presence above 20khz. Jneutron's source concluded 2us (us = microseconds).
 
Secondly, the Shogo Kiryu and Kaoru Ashihara paper also contradicts the research and measurements of Oohashi, Nishini, Honda, Yonekura, Fuwamoto, Kawai, Maekawa, Nakamura, Fukuyama and Shibasaki,
presented in "Journal of Neurphysiology", for those interested. Again real medical science and actual PET and EEG measurements were involved.
They demonstrated, using PET and EEG scans, that the brain perceives a difference when above 20khz is added to music with a bandwidth of 20-20khz. Of course it costs more for industry when dealing with higher frequencies.

It is quite clear that Shogo Kiryu and Kaoru Ashihara's work contradicts main stream medical and other sciences in at least  two important aspects, as mentioned above.

See my previous posts for more information.
 
Cheers and hope you had a great Thanksgiving Ethan.

ps. The market will do whatever the market will do, so I will leave it at that. For Redbook, one
probably should remove artifacts above approx 20khz.

[TF1216]

Anyone have experience designing a DAC with and without the low pass filter?  Were low pass filters used in the tweeter crossovers at the inception of digital playback?

[brj]

While this was alluded to earlier in the thread before the side discussion on the upper limit of human hearing, the filter in a DAC is a reconstruction filter designed to prevent aliasing of higher frequencies down into the signal bandwidth (20Hz-20kHz).  It is analogous to the anti-aliasing filter used by an ADC when recording the music originally.  The need for it is driven by sampling theory.  Basically, to recreate a perfect waveform, a DAC must remove all signal information above the Nyquist frequency of 22050 Hz (which is 1/2 * 44100 samples/second for Redbook CD), and the act of sampling itself adds content at multiples of the frequency being sampled.

The wikipedia article on aliasing might be a helpful place to start.

(Note that the Nyquist frequency of 2x your signal bandwidth only guarantees proper capture of your signal frequency.  You'd prefer to sample at much higher rates to properly capture the signal amplitude.  Sampling a sawtooth wave at only 2x its frequency, for example, will result in rounded "teeth" rather than perfectly sharp points.  For what it's worth, the instrumentation gurus I know at work use a 10x rule of thumb, where they try to sample at 10x the highest frequency signal of interest.)

[TF1216]

Thank you for the explanation brj.  I'm going to read more on the web and come back to this. 

[Ethan Winer]

I see no measurements, just speculation.

What part of "nobody could hear it" is unclear? The article is AES Convention Paper 5401 Presented at the 110th Convention 2001 May 12–15 Amsterdam. This is a for-pay article so I can't just post it for the public. If you don't have this paper, email me through my web site www.ethanwiner.com and I'll send you the PDF. In the mean time, this part describes the test subjects:

"Ten males and 3 females participated as the subjects. All of them were either undergraduate or graduate students and had normal hearing. Their ages ranged between 19 and 26 years. They were paid for their participation. None of them could detect any stimulus above 22 kHz when it was presented as a single tone with the level below 85 dB SPL."

In my previous post, I had no reservations posting/listing the massive medical backup, from at least three national medical organizations, plus electronics, electrical engineering, universities, physics etc, who actually do the research. In otherwards, mainstream science.

Unless I missed something, you didn't post any actual evidence or study excerpts. You just made a claim and left it at that. Were the tests you cite flawed in the same way as Oohashi, where in-band IM products were present? Do you have a description of the test setup? Can you cite any specific papers showing that some people can hear higher than 22 KHz?

So it is not surprising that they would attack with a vengeance Dr. Kunchur, Oohashi, Nishini etc.

The problem with Oohashi's test is self-evident, as already explained. But I should have been clearer in my post yesterday. If you read through that Hydrogen Audio thread I linked, you'll see that Kunchur's main mistake was not realizing that bit-depth affects the time resolution of digital audio. So if I understand it correctly, Kunchur was off by a factor of 16 since each of the 16 bits in a CD quality Wave file doubles the available time resolution.

multiple national mainstream medical organizations dealing with hearing, multiple main stream academia, engineers, physicists, peer reviewers, main stream science

That's just Argument From Authority, without actually making a case.

at least two members who have posted in that string have been witnessed on other forums (Stereophile, AVS etc) altering Dr. Kunchur's work/conclusion and Oohashi, Nishini etc PET/EEG measurements, and claiming the tests were flawed. Both eventually admitted they presented false information. That raises the question of ethics.

And that's just an Ad Hominem attack. I was there and witnessed those discussions, and they were nothing like what you describe. Do you have a link to HA forum participants admitting they presented false information?

Dr. Kunchur's paper demonstrated, and concluded that a 5us timing change for each ear,
independent of the other ear, was perceived; which does require ultra sonic information to be available.

I'm sorry Steve, but this is simply incorrect. As JJ explained clearly, regular CDs have that much timing resolution too. Again, what you and Kunchur miss is that the number of bits used increases the resolution.

What I don't understand is why some audiophiles feel the need to prove we can hear ultrasonic content. It's like a holy grail for some people, even though it defies 100 years of audio knowledge. Even if it were true that in some rare situations people can perceive ultrasonic content, so what? Why does this matter? This is a serious question I wish someone would explain to me.

---Ethan

[Steve]

What part of "nobody could hear it" is unclear? The article is AES Convention Paper 5401 Presented
at the 110th Convention 2001 May 12–15 Amsterdam. This is a for-pay article so I can't just post it for
the public. If you don't have this paper, email me through my web site www.ethanwiner.com and I'll
send you the PDF. In the mean time, this part describes the test subjects:

"Nobody could hear it" means nothing. If the data is strong, paraphrase How the data was
arrived at, the procedures, for the public. Obviously it was not measured data.

"Ten males and 3 females participated as the subjects. All of them were either undergraduate
or graduate students and had normal hearing. Their ages ranged between 19 and 26 years. They were
paid for their participation. None of them could detect any stimulus above 22 kHz when it was
presented as a single tone with the level below 85 dB SPL."

See above. Obviously no measurements were taken in the Shogo Kiryu and Kaoru Ashihara
experiment.
Again, please detail the procedure, how did they obtained their data.

The PET and EEG scans of the Oohashi etc work also did Not detect any brain activity when Only
ultrasonics was applied. This has already been mentioned in my two previous posts. So your
information concerning the Shogo Kiryu and Kaoru Ashihara paper is dismissed.
 
However, the Oohashi, Nishini, Honda, Yonekura, Fuwamoto, Kawai, Maekawa, Nakamura, Fukuyama
and Shibasaki work goes farther, as mentioned in my previous posts. Please study my posts again.

Unless I missed something, you didn't post any actual evidence or study excerpts. You just
made a claim and left it at that. Were the tests you cite flawed in the same way as Oohashi, where
in-band IM products were present? 

Why not contact Oohashi for an explanation and post the reply here.

How do you discredit a paper you admit you have not read.
Secondly, folks the Oohashi, Nishini, Honda, Yonekura, Fuwamoto, Kawai, Maekawa, Nakamura,
Fukuyama and Shibasaki acknowledgments. Again solid mainstream medical and acadamia.

We thank the staff of the Kyoto University PET Center for valuable contributions to this work;
Dr. Yoshio Yamasaki, Waseda University, for the use of his recently developed signal processing system;
the Yamashiro Institute of Science and
Culture for recording the sound sources; Dr. Norihiro Sadato, National Institute for Physiological Sciences,
for valuable comments on an early version of the manuscript; and Dr. Masako Morimoto, Japan Society
for the Promotion of Science, for valuable technical support.
This work was supported in part by the Japan Ministry of Education, Science and Culture, through the
Grants-in-Aid for Scientific Research (A) (09490031) to T. Oohashi, on Priority Areas to H. Shibasaki,
and for International Scientific Research Program (10041144) to T. Oohashi, and by the Japan Society
for the Promotion of Science through the Research for the Future Program JSPS-RFTF 97L00201 to
H. Shibasaki.

The problem with Oohashi's test is self-evident, as already explained. But I should have been clearer
in my post yesterday. If you read through that Hydrogen Audio thread I linked, you'll see that Kunchur's
main mistake was not realizing that bit-depth affects the time resolution of digital audio. So if I
understand it correctly, Kunchur was off by a factor of 16 since each of the 16 bits in a CD quality
Wave file doubles the available time resolution.

I suggest you re-read the paper, contact Dr. Kunchur, maybe he will answer or forward to another
expert in the field, and then report back. Also, there are other works cited in
his paper, 10us is perceptible, again requiring ultra sonics.

That's just Argument From Authority,
without actually making a case.

Well, they are mainstream science, the PHds. from main stream medicine,
acagemia/universities, physics professors, mathematics, the ones who actually perform the research
and either write and/or assist those who write the papers, do the peer reviews.

 

And that's just an Ad Hominem attack. I was
there and witnessed those discussions, and they were nothing like what you describe. Do you have a link
to HA forum participants admitting they presented false information?

It was on Stereophile and AVS forums and were witnessed.

 

I'm sorry Steve, but this is simply incorrect. As JJ explained clearly, regular CDs have that much
timing resolution too. Again, what you and Kunchur miss is that the number of bits used increases the
resolution.

We are talking Stereophile forums in which he claimed all one has to do is delay the musical signal by 5us from one to the other (a very simple circuit), when Dr. Kunchur said it was per ear "there is no "interaural time difference" (much more complicated). . Again, I suggest contacting Dr. Kunchur with your questions.
However, let us check out Ethan's quote of JJ "regular CDs have that much timing resolution too" in the graph below. One can see the inaccuracy of a 3us pulse at 48k (not 44.1k), and 5us is not much better. Notice the slope (rise time), ringing, distortion with 48k. (Imagine Dr. Kunchur and others using 48k for scientific testing.)



Concerning questionable comments, Dr. Kunchur states.

First of all, an internet forum is a dangerous place to obtain information -- instead one should go
to an authentic original source such as a published scientific paper in a refereed journal. In such a forum,
a writer can post completely arbitrary, unproven, and indeed totally wrong statements with no backing
or oversight whatsoever. Normally this would be a laughing matter, except that sometimes people
obtain their "education" through such forums and this can therefore cause longterm and serious damage...
For those who have no idea what science and the (incredibly rigorous) scientific process is, let me explain
what went into publishing the two above mentioned papers that have apparently generated controversy
among lay readers (but no controversy whatsoever in all the professional circles, which include audiolists, otolaryngologists, acousticians, engineers, and physicists )...

 

What I don't understand is why some audiophiles feel the need to prove we can hear
ultrasonic content. It's like a holy grail for some people, even though it defies 100 years of audio
knowledge. Even if it were true that in some rare situations people can perceive ultrasonic content,
so what? Why does this matter?

Because the public wants the highest quality music possible and could care less about industries bottom
line. 
Because mainstream science has demonstrated that mp3 and redbook is inferior. We would like the
best, not submit to lower quality because it saves the industry some bucks.

When finished contacting Dr. Kunchur, please post his response.

Both Dr. Kunchur and Oohashi, Nishini, Honda, Yonekura, Fuwamoto, Kawai, Maekawa, Nakamura,
Fukuyama and Shibasaki's work are on solid main stream medical and academia ground.
Personally I am sticking with mainstream medicine/science.

Cheers.

[Speedskater]

Steve wrote:
However, let us check out Ethan's quote of JJ "regular CDs have that much timing resolution too" in the graph below. One can see the inaccuracy of a 3us pulse at 48k (not 44.1k), and 5us is not much better. Notice the slope (rise time), ringing, distortion with 48k. (Imagine using it for scientific testing.)

I see no  inaccuracy, ringing or distortion! Also the slope (rise time) is appropriate.   All of these traces are what you get when you try to run an ultrasonic signal through a low-pass filter. Your chart has nothing to do with timing resolution.

[Ethan Winer]

Your chart has nothing to do with timing resolution.

Nor does the rest of his post address anything relevant, or off any proof beyond "Go ask Oohashi and Kunchur."

I'm still waiting to hear why some people think the audibility of ultrasonic content matters, when so many other things affect audio reproduction quality in much more real and meaningful ways.

--Ethan

[Steve]

Please delete.

Cheers.
Steve

[Steve]

Steve wrote:
However, let us check out Ethan's quote of JJ "regular CDs have that much timing resolution too" in the graph below. One can see the inaccuracy of a 3us pulse at 48k (not 44.1k), and 5us is not much better. Notice the slope (rise time), ringing, distortion with 48k. (Imagine using it for scientific testing.)

I see no  inaccuracy, ringing or distortion! Also the slope (rise time) is appropriate.   All of these traces are what you get when you try to run an ultrasonic signal through a low-pass filter. Your chart has nothing to do with timing resolution.

Better look again. Check amplitudes, width, compare slopes (rise time and fall time), ringing, all forms of distortion. One doesn't perform a sloppy test if one wishes to remain credible in mainstream science. Any changes are forms of distortion which are clearly seen.
And one cannot use 48k (approx. 20k bandwidth) for checking 5us differences between signals. And we are not discussing two channels.
The width and slope (rise time) has everything to do with resolving two signals, per one channel, just one ear, 5us apart since the 20-20k bandwidth is not capable of differentiating them.
One can understand why Dr. Kunchur used a different method and won approval with multiple medical organization, scientists, engineers etc to make sure all was correct. That is why we stick with mainstream science.

Ethan you have been informed, PET and EEG measurements were taken and approved by those of mainstream medical and mainstream science. Gents, if you have a disagreement with Dr. Kunchur or Oohashi work, take it up with them, obtain their papers and study them instead of back biting them through me.

Cheers.