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  • 2Bdecided
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Interesting Papers re temporal resolution
Reply #75
Also, for his FAQ example of two peaks separated by 5 microseconds, my statement still holds true.  The two peaks will "ring" the anti-alias filter in such a way that those two peaks still have an impact into the digital sampling (and on the eventual post-reconstruction-filter output).  The waveform will look different and the high frequency spectra will be lost but the "information" of the two separate peaks will remain in the final analog output.
To be accurate and clear, the bit you can hear remains - which is all anyone wanting to listen to the audio signal should care about.

Cheers,
David.

  • honestguv
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Interesting Papers re temporal resolution
Reply #76
They are supposed to repesentation two sounds occuring nearly, but not quite, simultaneously, for example two drums where the mallets hit 5 microseconds apart.

The time signals of two drums is not two impulses 5 microseconds apart. An impulse would normally represent something physical and have a known "height" and "width" to use Dr. K.s terminology (or was it vertical and horizontal?). What are the "heights" and "widths" in this case? If they are not known then what can you say about what should be going on in frequency space? Is "energy" conserved which is normally the first check performed when mapping between spaces?

Or are we talking about 2 periodic signals 5 microseconds apart? If so, what are they...

Unless there is a comprehensible statement of a problem one cannot say if it is right or wrong. All one can say is that it is incomprehensible.

The proper way to test would be [...]

Perhaps.

  • ExUser
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Interesting Papers re temporal resolution
Reply #77
I just had a random thought about this and I wanted to run it by here:

The experimental procedure calls for a low-pass filtering of the signal. Does low-pass filtering significantly affect the perceived volume? Could the low-pass filter's effect on the perceived loudness be the perceived trait here? It is well-documented that decrease in loudness is perceived as decrease in quality. By slightly amplifying the filtered signal, could the perceived difference disappear?

So then, could the simple existence of the higher-order harmonics affect the overall power-spectrum (I'm aware that it will obviously be different in the frequency domain) significantly enough to be perceptible?

  • andy_c
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Interesting Papers re temporal resolution
Reply #78
Well, the 4.7us time constant does decrease the level of the 7 kHz fundamental by 0.18 dB, which he mentions in his paper.  According to a description in his paper of another experiment (done by a different author), the just noticeable difference is 0.7 dB at that frequency.
  • Last Edit: 03 August, 2009, 10:40:06 PM by andy_c

  • WernerO
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Interesting Papers re temporal resolution
Reply #79
Please re-read the part I just bolded in the "quote" block above.


Agree. Sloppy reading on my part.

Then again, perhaps you should be a bit more explicit for those not versed in the art?


  • andy_c
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Interesting Papers re temporal resolution
Reply #80
Here's another thing I noticed in his test apparatus.  He describes the switching of the filter time constants and how it was optimized to minimize switching transients.  He states that "...relays (which can induce a disturbance through magnetic flux change) were avoided...", although he does not say whether he tried any, and if so, whether this alleged disturbance was a problem in practice.  The advantage of a relay would be to allow computer control of the switching, which when performed with the appropriate software, would allow for double-blind testing.  IOW, it would allow for a test in which only the software, and not the test administrator, "knows" the state of the switch at any given time.  He further states "...switch-bounce distortion was avoided by minimizing contact areas...", so this implies that a mechanical switch was used.  Since that switch isn't a relay, it's just going to be a purely manual switching arrangement done by the test administrator physically flipping the switch.  This in turn says that the test administrator is aware of the state of the switch at all times.  It is therefore not a double-blind test.  He does take care to call his tests "blind tests" rather than double-blind, so that is good.  He uses the phrase "very effective blind listening tests" at one point in his article in fact.  But he doesn't spell out what precautions, if any, were used to prevent the test subjects from observing the test administrator, which has the potential to influence the test results (AKA the Clever Hans Effect).

  • benski
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Interesting Papers re temporal resolution
Reply #81
Please re-read the part I just bolded in the "quote" block above.


Agree. Sloppy reading on my part.

Then again, perhaps you should be a bit more explicit for those not versed in the art?


When I get some spare time this week, I'll put together a good example including waveform and spectral plots.  The basic idea is that the the magnitude and (more importantly) phase response of the digital signal will be the same below the nyquist frequency.  The digital waveform might not look the same, but the information that your ears use to detect that 5 microsecond timing difference is still there. 


  • ncdrawl
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Interesting Papers re temporal resolution
Reply #82
we don't have to re-read all all of the time?
Further, there already is something interesting in an earlier
version of the FAQ document that is missing in the present one, if I remember
correctly.

It had to do with the time accuracy of 44.1kHz sampled systems ;-)




I wouldn't speculate. Don't speak such things unless you know them to be factual..that's how rumors get started, you know.

and no, he isn't updating his FAQ ie changing his answers... he is updating IE ACCOMMODATING NEW QUESTIONS THAT HE RECEIVES AFTER THE OLD FAQ WAS PUBLISHED>...

Interesting Papers re temporal resolution
Reply #83
Here's another thing I noticed in his test apparatus.  He describes the switching of the filter time constants and how it was optimized to minimize switching transients.  He states that "...relays (which can induce a disturbance through magnetic flux change) were avoided...", although he does not say whether he tried any, and if so, whether this alleged disturbance was a problem in practice.  The advantage of a relay would be to allow computer control of the switching, which when performed with the appropriate software, would allow for double-blind testing.


As a rule, relays don't induce significant disturbances in the signals they control when they change state. For example, one of the benchmarks for the ABX RM-2 relay module was an audibly transient-free switchover between two integrated amplifiers including phono or microphone input stages.

http://www.provide.net/~djcarlst/abx_rm2.htm

The production RM2 was based on reed relays with 5 volt coils, but its first adequate prototype (equally effective) was based on traditional open-frame, open-contact relays with 28 volt coils. Damping networks were placed across relay coils to prevent arcing and damage to the control circuits.

Transient free switching of audio gear is not always trivial, but the important issues are related to the actual oder and kind (NC or NO) of contact openings. The original Clark JAES article tells all.

Paranoia about relay contacts is just another high end audiophile straw man. Professional audio gear and communications equipment has been reliably switching audio signals with relays for over a century.

  • ultrasonic
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Interesting Papers re temporal resolution
Reply #84
Nobody seems to be able to do it. Instead, all we get are these abstract tests like Kunchur's, involving some most definately non-musical waveforms with questionable relevance and inconclusive results.


I agree. Not a single positive result in a decade is simple but mortgageable evidence.


Does this count?:

http://www.avsforum.com/avs-vb/showpost.ph...mp;postcount=28

  • Woodinville
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Interesting Papers re temporal resolution
Reply #85
Nobody seems to be able to do it. Instead, all we get are these abstract tests like Kunchur's, involving some most definately non-musical waveforms with questionable relevance and inconclusive results.


I agree. Not a single positive result in a decade is simple but mortgageable evidence.


Does this count?:

http://www.avsforum.com/avs-vb/showpost.ph...mp;postcount=28



Perhaps you might detail the testing setup and apparatus, and the length of the test for us?
-----
J. D. (jj) Johnston

  • ultrasonic
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Interesting Papers re temporal resolution
Reply #86
Nobody seems to be able to do it. Instead, all we get are these abstract tests like Kunchur's, involving some most definately non-musical waveforms with questionable relevance and inconclusive results.


I agree. Not a single positive result in a decade is simple but mortgageable evidence.


Does this count?:

http://www.avsforum.com/avs-vb/showpost.ph...mp;postcount=28



Perhaps you might detail the testing setup and apparatus, and the length of the test for us?


The links to the study are on that page, but here they are directly:

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

http://jn.physiology.org/cgi/reprint/83/6/3548

Interesting Papers re temporal resolution
Reply #87
Nobody seems to be able to do it. Instead, all we get are these abstract tests like Kunchur's, involving some most definately non-musical waveforms with questionable relevance and inconclusive results.


I agree. Not a single positive result in a decade is simple but mortgageable evidence.


Does this count?:

http://www.avsforum.com/avs-vb/showpost.ph...mp;postcount=28


In the opinon of many, no.

Interesting Papers re temporal resolution
Reply #88






Nobody seems to be able to do it. Instead, all we get are these abstract tests like Kunchur's, involving some most definately non-musical waveforms with questionable relevance and inconclusive results.


I agree. Not a single positive result in a decade is simple but mortgageable evidence.



Does this count?:

http://www.avsforum.com/avs-vb/showpost.ph...mp;postcount=28




Perhaps you might detail the testing setup and apparatus, and the length of the test for us?


The links to the study are on that page, but here they are directly:

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


This link appears to be broken.

The correct link appears to be:

http://www.ocf.berkeley.edu/~ashon/audio/Ultrasonics.htm

This appears to be a year 2000 summary of the well-known Boyk paper that only documents the allready well-known existence of ultrasonic harmonics from musical instruments.

"This completely different paradigm for digital audio recording (SACD) does away with the anti-alias filters needed for PCM (CD and DVD-A) analogue waveform reconstruction. Preliminary reports in the audiophile community indicate that SACD has a natural quality of sound that DVD-A has yet to demonstrate. Ironically, one of the descriptions of SACD, this radically new digital format, is that it sounds "like analogue", meaning like LPs, ancient technology. (LPs i.e. vinyl records are associated with having smooth, relaxing presentations, that while sometimes not as impressive per audiophile standards, nevertheless can offer perfectly enjoyable music. The same is not always true, and in fact is seldom true, for CDs.)"

This is not evidence, it is supposition. Furthermore, the article contains errors of fact, some that were known to be errors when it was written, others that have come to light since it was written.

Quote
http://jn.physiology.org/cgi/reprint/83/6/3548


This is the oft-debunked Oohashi paper.

  • Last Edit: 02 January, 2010, 12:44:24 AM by Arnold B. Krueger

  • ultrasonic
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Interesting Papers re temporal resolution
Reply #89
Nobody seems to be able to do it. Instead, all we get are these abstract tests like Kunchur's, involving some most definately non-musical waveforms with questionable relevance and inconclusive results.


I agree. Not a single positive result in a decade is simple but mortgageable evidence.


Does this count?:

http://www.avsforum.com/avs-vb/showpost.ph...mp;postcount=28


In the opinon of many, no.


Opinion isn't good enough. The paper is scientific and peer-reviewed. It may be flawed, but if so it needs to be debunked scientifically. Can you provide links to similarly peer-reviewed refutations of the paper?

Interesting Papers re temporal resolution
Reply #90
Nobody seems to be able to do it. Instead, all we get are these abstract tests like Kunchur's, involving some most definately non-musical waveforms with questionable relevance and inconclusive results.


I agree. Not a single positive result in a decade is simple but mortgageable evidence.


Does this count?:

http://www.avsforum.com/avs-vb/showpost.ph...mp;postcount=28


In the opinon of many, no.


Opinion isn't good enough.


Then your opinion is also not good enough, and that should be the end of your contributions to this thread. Do you want to go there? ;-)

Quote
The paper is scientific and peer-reviewed.


That does not make it infallible.

Quote
It may be flawed, but if so it needs to be debunked scientifically.


That has been done. The paper has always been weak. It was shopped around as a conference paper in several places before a journal that was weak enough to publish it was found.

Quote
Can you provide links to similarly peer-reviewed refutations of the paper?


That's unecessary. The universe is full of of peer-reviewed papers that became false when other relevant information became known. That is the nature of science.



  • Woodinville
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Interesting Papers re temporal resolution
Reply #91
Opinion isn't good enough. The paper is scientific and peer-reviewed.

So, if a paper comes out that claims, oh, say, that ESP works, and is published in an ESP journal, "opinion is not enough" even though there has never, ever, to date, been an unbiased test of ESP that shows it works.  (Hint: Such papers exist.)

So, if a paper comes out in the journal of the ICR, showing that we were all created 6000 years ago, and the Grand Canyon was made during the "great flood", "opinion is not enough" even though in reputable journals there are thousands of pages on the erosion history of the Grand Canyon during the rise of the Colorado Plateau.  (Hint: Such papers exist.)

So, if a paper comes out and gets published in a very odd journal that says "rocks fall up", "opinion is not enough" even if the rock always falls on your toe? (I'm not aware of any such papers, thankfully, although some TM practitioners claim you can levitate by meditation, I don't think even TM journals have published it as a "paper".)
Quote
It may be flawed, but if so it needs to be debunked scientifically. Can you provide links to similarly peer-reviewed refutations of the paper?


I think it's time for a reality check.  "peer-reviewed refutations" is not what you will see in a  journal.  You're asking for something that is never going to exist, it's not how the system works.

What you will see is work showing something that reads on the subject, positive, negative, whatever.

And there is an entire forest of paper on that, dating from the 1920's to present.

Before any weight is put on the paper, it has to be REPEATED AND CONFIRMED. That is the scientific process. Going on about "peer reviewed" misses the mark in so many ways I hardly know where to start.  The paper provides a presumed means to allow confirmation or perhaps not confirmation.  As such, even if the reviewer has doubts, it may be published simply to start a dialog.  Controversial papers are published, I ought to know, I published a couple of early papers on audio coding in light of reviewers who basically accused me of lying through my teeth. Yet, the papers were published, others also published, and now most everyone on the planet uses some form of the technology.

If you want to support this premise, repeat the experiment and see if you can confirm the results.  You might even try to improve the experimental process, and try several different kinds of ultrasonic stimulii to see what's going on.

Finally, as a comment on ultrasonic stimulii, please check http://www.csgnetwork.com/atmossndabsorbcalc.html for the performance of the atmosphere under conditions of no wind, static atmosphere, etc.

Then consider the effects of wind and turbulence.
-----
J. D. (jj) Johnston

Interesting Papers re temporal resolution
Reply #92
Before any weight is put on the paper, it has to be REPEATED AND CONFIRMED. That is the scientific process. Going on about "peer reviewed" misses the mark in so many ways I hardly know where to start.  The paper provides a presumed means to allow confirmation or perhaps not confirmation.  As such, even if the reviewer has doubts, it may be published simply to start a dialog.  Controversial papers are published, I ought to know, I published a couple of early papers on audio coding in light of reviewers who basically accused me of lying through my teeth. Yet, the papers were published, others also published, and now most everyone on the planet uses some form of the technology.


The Oohashi paper is now about 10 years old. No confirmation, only failed attempts to confirm it.

Confirming it 10, 8 years ago (been there done that) was more difficult. Confirming it today is very easy. Interesting that so many of its advocates have not reported any of their own personal attempts to confirm it.

Quote
If you want to support this premise, repeat the experiment and see if you can confirm the results.  You might even try to improve the experimental process, and try several different kinds of ultrasonic stimulii to see what's going on.


Been there, done that and I also failed to confirm it. Multiple test systems, multiple test music sources, multiple listeners.
  • Last Edit: 02 January, 2010, 07:27:49 AM by Arnold B. Krueger

  • krabapple
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Interesting Papers re temporal resolution
Reply #93
Opinion isn't good enough. The paper is scientific and peer-reviewed. It may be flawed, but if so it needs to be debunked scientifically. Can you provide links to similarly peer-reviewed refutations of the paper?


You could have searched HA for previous discussion of Oohashi et al., you know.  It's not like it hasn't been offered as evidence a half dozen times already.

http://www.hydrogenaudio.org/forums/index....st&p=606769

http://www.hydrogenaudio.org/forums/index....st&p=607276

  • Last Edit: 03 January, 2010, 12:45:17 AM by krabapple

  • Pio2001
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Interesting Papers re temporal resolution
Reply #94
Hello, I've just read the first and third articles of Milind Kunchur. I think that I found a weak point in his work. But first, a few comments on the discussion

Since changes in this second harmonic value could explain the experimental results without needing some hypothesis regarding the alleged ability of the ear to detect signals above the frequency limit of human hearing, it's essential to include these data.  Yet he fails to do so.


Kunchur speaks about second harmonics created in the middle ear, after the eardrum, but before reaching the hair cells, where ultrasonic frequencies are dead stopped. Therefore the hypothesis remains correct even of no second harmonic at all is outputted from the speaker.

However, he doesn't speak about the amplitude of this harmonic, probably unknown, and let an arbitrary factor b in front of the calculus.
In practice, this intermodulation seem to be extremely low, if it ever exists, as 2bdecided recalls :

all previous proper experiments show that, apart from via bone conduction, ultrasonics don't distort to create audible frequencies in the ear.

In equipment, yes, but not in the ear.

If someone proves otherwise (quite possible), it'll be interesting.

IIRC there was someone here who did (playing ultrasonic from a separate audio system(!) and ABXing presence / absence in the presence of an audible sound), but I didn't see how the thread ended.


I remember that Nika Aldrich and I, in an old discussion in George Massenbug forum, once ran this experiment : play a set of two frequencies in a speaker, one audible, one inaudible. I chose 12 kHz and 18 kHz. The 4 kHz intermodulation was clearly audible. Then, play one of them in the left speaker of your stereo, and the other in the right speaker. No intermodulation was audible anymore.

From the first paragraph at: www.physics.sc.edu/kunchur/Acoustics-papers.htm
Quote
Our recent behavioral studies on human subjects proved that humans can discern timing alterations on a 5 microsecond time scale, indicating that that digital sampling rates used in common consumer audio (such as CD) are insufficient for fully preserving transparency.


This statement contains a glaring error:

44.1 kHz sampling PCM systems are perfectly capable of reproducing the phase of audible frequencies to picosecond accuracy.  The need for 5-microsecond temporal accuracy does NOT indicate the need for a higher sample rate.  It simply indicates that jitter must be less than 5-microseconds.


True, but Kunchur's first paper is actually not about temporal resolution. The blind test was comparing a full-band signal versus a lowpassed version of the same signal. Thus the conclusion about sample rates is relevant.

Nobody seems to be able to do it. Instead, all we get are these abstract tests like Kunchur's, involving some most definately non-musical waveforms with questionable relevance and inconclusive results.


I agree. Not a single positive result in a decade is simple but mortgageable evidence.


Kunchur's results are positive !
We can question them, critic the methodology, find flaws and discuss them, so the conclusion is not clear yet, but they are positive.

Well, the 4.7us time constant does decrease the level of the 7 kHz fundamental by 0.18 dB, which he mentions in his paper.  According to a description in his paper of another experiment (done by a different author), the just noticeable difference is 0.7 dB at that frequency.


...and that's the weak point that I wanted to talk about. The 0.7 dB threshold is assumed without checking. Kunchur says in the FAQ that he can't redo everything and that evaluating again the Just Noticeable Difference would take about two years.

However, since this point annoyed me, I ran an ABX test between two 7 kHz sines. I chose the level difference that Kunchur got for the 5.6 µs lowpass experiment : 0.25 dB.

I generated two 7 kHz sines using Soundforge. Since the software is all 16 bits, I decreased the volume of the first one by 1 dB, and of the second one by 1.25 dB, in order to get the same quantization noise on both.

I could ABX them with a score of 8/8 with Foobar2000 ABX module, no DSP, no replaygain. I was wearing headphones and the playback volume was moderate. Inferior to 80 dB, but I couldn't say how much.

I had to perform instant switches back and forth in order to hear the difference. Foobar2000 cuts the signal for a fraction of second each time I press a button. Like the listeners in Kunchur's experiments, I found the louder sine "brighter".

Therefore the assumption that the level Just Noticeable Difference for a 7 kHz sine at 69 dB is 0.7 dB seems seriously flawed, and that questions all Kunchur's results.
  • Last Edit: 18 April, 2010, 06:13:23 PM by Pio2001

  • C.R.Helmrich
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Interesting Papers re temporal resolution
Reply #95
Therefore the assumption that the level Just Noticeable Difference for a 7 kHz sine at 69 dB is 0.7 dB seems seriously flawed, and that questions all Kunchur's results.

Pages 180 and 181 of "Psychoacoustics: Facts and Models" by Fastl/Zwicker say it all:

http://books.google.com/books?id=eGcfn9ddR...1&lpg=PA181
[Edit: http://www.google.com/search?q=just-notice...evel+difference, in case the above link doesn't work]

Quote
A typical characteristic of just-noticeable amplitude modulation of sinusoidal tones is the level dependence. Almost the same level dependence is measured for just-noticeable differences in level [JNDL], as indicated in Fig. 7.5. For low sound pressure levels below 20 dB, JNDL increases greatly towards threshold, but decreases from about 0.4 dB at 40 dB to about 0.2 dB at 100 dB sound pressure level. The decrement seems to be not quite as strong as for amplitude modulation, but the characteristic is similar to the data shown by the solid line in Fig. 7.1. This characteristic is almost independent of frequency if, instead of the sound pressure level, the level above threshold (or, even better, the loudness level) is used as the abscissa.

A 7-kHz tone is only a few dB quieter than a 1-kHz tone: http://en.wikipedia.org/wiki/Equal-loudness_contour. So with your 0.25 dB, you're well in line with Zwicker's findings.

Chris
  • Last Edit: 18 April, 2010, 07:20:17 PM by C.R.Helmrich
If I don't reply to your reply, it means I agree with you.

Interesting Papers re temporal resolution
Reply #96
Nobody seems to be able to do it. Instead, all we get are these abstract tests like Kunchur's, involving some most definately non-musical waveforms with questionable relevance and inconclusive results.


I agree. Not a single positive result in a decade is simple but mortgageable evidence.


Kunchur's results are positive !
We can question them, critic the methodology, find flaws and discuss them, so the conclusion is not clear yet, but they are positive.

Well, the 4.7us time constant does decrease the level of the 7 kHz fundamental by 0.18 dB, which he mentions in his paper.  According to a description in his paper of another experiment (done by a different author), the just noticeable difference is 0.7 dB at that frequency.


...and that's the weak point that I wanted to talk about. The 0.7 dB threshold is assumed without checking. Kunchur says in the FAQ that he can't redo everything and that evaluating again the Just Noticeable Difference would take about two years.

However, since this point annoyed me, I ran an ABX test between two 7 kHz sines. I chose the level difference that Kunchur got for the 5.6 µs lowpass experiment : 0.25 dB.

I generated two 7 kHz sines using Soundforge. Since the software is all 16 bits, I decreased the volume of the first one by 1 dB, and of the second one by 1.25 dB, in order to get the same quantization noise on both.

I could ABX them with a score of 8/8 with Foobar2000 ABX module, no DSP, no replaygain. I was wearing headphones and the playback volume was moderate. Inferior to 80 dB, but I couldn't say how much.

I had to perform instant switches back and forth in order to hear the difference. Foobar2000 cuts the signal for a fraction of second each time I press a button. Like the listeners in Kunchur's experiments, I found the louder sine "brighter".

Therefore the assumption that the level Just Noticeable Difference for a 7 kHz sine at 69 dB is 0.7 dB seems seriously flawed, and that questions all Kunchur's results.


Disclaimer: My comments were about musical sounds, not lengthy pure sine waves.

  • Woodinville
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Interesting Papers re temporal resolution
Reply #97
It is interesting to note that now the same people at stereophile are ragging on Sean Olive. First a guy claimed that Sean's blog was sending out viruses, and that got squashed, now he's claiming that Sean doesn't know how to run a listening test.

This is the same person who alleges I don't know what an impulse response is, doesn't know the difference between an impulse response and signal detection, and who regards my speaking on a panel with Ethan Winer as "travelling 6000 miles to aid a competitor".
-----
J. D. (jj) Johnston

Interesting Papers re temporal resolution
Reply #98
It is interesting to note that now the same people at stereophile are ragging on Sean Olive. First a guy claimed that Sean's blog was sending out viruses, and that got squashed, now he's claiming that Sean doesn't know how to run a listening test.

This is the same person who alleges I don't know what an impulse response is, doesn't know the difference between an impulse response and signal detection, and who regards my speaking on a panel with Ethan Winer as "travelling 6000 miles to aid a competitor".



I presume this is the Stereophile forum, not the ragazine. I've stopped paying much attention to what happens there, because it really doesn't seem to matter a lot in the real world.

  • Paulhoff
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Interesting Papers re temporal resolution
Reply #99
It is interesting to note that now the same people at stereophile are ragging on Sean Olive. First a guy claimed that Sean's blog was sending out viruses, and that got squashed, now he's claiming that Sean doesn't know how to run a listening test.

This is the same person who alleges I don't know what an impulse response is, doesn't know the difference between an impulse response and signal detection, and who regards my speaking on a panel with Ethan Winer as "travelling 6000 miles to aid a competitor".

You're not doing it right JJ, Stereophile will not even let me join the forum. It is just great, I can't go crazy trying to straighten those BOZO posters out on that forum.

Paul

     
"Reality is merely an illusion, albeit a very persistent one." Albert Einstein