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Interesting Papers re temporal resolution
ncdrawl
post Jul 25 2009, 07:27
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http://www.physics.sc.edu/kunchur/Acoustics-papers.htm

http://www.physics.sc.edu/kunchur/papers/FAQs.pdf
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Canar
post Aug 4 2009, 02:41
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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?


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andy_c
post Aug 4 2009, 02:57
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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.

This post has been edited by andy_c: Aug 4 2009, 03:40
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Pio2001
post Apr 18 2010, 23:07
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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

QUOTE (andy_c @ Jul 29 2009, 16:52) *
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 :

QUOTE (2Bdecided @ Aug 1 2009, 08:24) *
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.

QUOTE (John_Siau @ Jul 31 2009, 19:16) *
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.

QUOTE (rpp3po @ Aug 3 2009, 01:42) *
QUOTE (Arnold B. Krueger @ Aug 3 2009, 02:24) *
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.

QUOTE (andy_c @ Aug 4 2009, 02:57) *
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 Ás 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.

This post has been edited by Pio2001: Apr 18 2010, 23:13
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C.R.Helmrich
post Apr 18 2010, 23:56
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QUOTE (Pio2001 @ Apr 19 2010, 00:07) *
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

This post has been edited by C.R.Helmrich: Apr 19 2010, 00:20


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Posts in this topic
- ncdrawl   Interesting Papers re temporal resolution   Jul 25 2009, 07:27
- - rpp3po   I'm not sure wether they have actually tested ...   Jul 25 2009, 13:17
- - Ethan Winer   Nice to see this topic here where it can be discus...   Jul 25 2009, 18:26
- - hellokeith   from the link: QUOTE Our recent behavioral studies...   Jul 25 2009, 20:39
|- - C.R.Helmrich   QUOTE (hellokeith @ Jul 25 2009, 21:39) D...   Jul 25 2009, 22:09
||- - rpp3po   QUOTE (C.R.Helmrich @ Jul 25 2009, 23:09)...   Jul 25 2009, 22:28
||- - Woodinville   QUOTE (rpp3po @ Jul 25 2009, 14:28) Well,...   Jul 28 2009, 09:27
|- - John_Siau   From the first paragraph at: www.physics.sc.edu/ku...   Jul 31 2009, 19:16
|- - andy_c   QUOTE (John_Siau @ Jul 31 2009, 12:16) Th...   Jul 31 2009, 21:30
- - hellokeith   Well after reading through the first 3 PDF's a...   Jul 26 2009, 01:24
- - Axon   Don't even bother using a square wave generato...   Jul 28 2009, 02:55
|- - rpp3po   Yes, I asked myself why Adobe would even include s...   Jul 28 2009, 03:06
- - Mike Giacomelli   I only skimmed the paper, but IIRC tried a digital...   Jul 28 2009, 03:31
- - Canar   Now the WAV files won't load in foobar2000... ...   Jul 28 2009, 03:51
|- - rpp3po   QUOTE (Canar @ Jul 28 2009, 04:51) These ...   Jul 28 2009, 11:37
|- - lvqcl   QUOTE (rpp3po @ Jul 28 2009, 14:37) Could...   Jul 28 2009, 12:52
|- - Mike Giacomelli   QUOTE (rpp3po @ Jul 28 2009, 06:37) Could...   Jul 28 2009, 15:58
- - Nick.C   Why not just just create a 7.35kHz square wave ...   Jul 28 2009, 13:13
|- - benski   QUOTE (Nick.C @ Jul 28 2009, 08:13) Why n...   Jul 31 2009, 15:39
|- - 2Bdecided   QUOTE (benski @ Jul 31 2009, 15:39) QUOTE...   Jul 31 2009, 16:33
|- - benski   QUOTE (2Bdecided @ Jul 31 2009, 11:33) QU...   Jul 31 2009, 16:39
- - Axon   Because that places unacceptable restrictions on t...   Jul 28 2009, 16:12
- - Canar   If I may grossly oversimplify your argument Axon, ...   Jul 28 2009, 19:46
|- - Axon   QUOTE (Canar @ Jul 28 2009, 13:46) If I m...   Jul 28 2009, 20:14
||- - andy_c   I'd like to add a few comments regarding the ...   Jul 29 2009, 16:52
||- - Axon   QUOTE (andy_c @ Jul 29 2009, 10:52) I...   Jul 29 2009, 17:11
||- - andy_c   QUOTE (Axon @ Jul 29 2009, 10:11) Well, g...   Jul 29 2009, 17:27
|- - Mike Giacomelli   QUOTE (Canar @ Jul 28 2009, 14:46) As an ...   Jul 28 2009, 21:08
|- - NullC   QUOTE (Mike Giacomelli @ Jul 28 2009, 12...   Jul 29 2009, 05:48
|- - Mike Giacomelli   QUOTE (NullC @ Jul 29 2009, 00:48) QUOTE ...   Jul 29 2009, 16:19
- - Axon   So, on that note.... an off topic comment. I just ...   Jul 29 2009, 17:01
|- - Canar   QUOTE (Axon @ Jul 29 2009, 09:01) So, on ...   Jul 29 2009, 18:18
- - krabapple   It may well be that Dr. Kunchur's audio work i...   Jul 29 2009, 17:04
- - kode54   Where did you come up with that 1.45GHz figure? Th...   Jul 29 2009, 20:22
- - Axon   Well, I'm thinking more specifically of the th...   Jul 29 2009, 20:41
- - Audible!   QUOTE (ncdrawl @ Jul 30 2009, 23:07) QUOT...   Jul 31 2009, 08:36
- - 2Bdecided   Yes, I see it now (having tried it!), it's...   Jul 31 2009, 17:13
- - John_Siau   From the summary paragraph in "Audibility of ...   Jul 31 2009, 19:37
|- - Axon   QUOTE (John_Siau @ Jul 31 2009, 13:37) Fr...   Jul 31 2009, 21:28
|- - John_Siau   QUOTE (Axon @ Jul 31 2009, 16:28) That se...   Jul 31 2009, 22:15
|- - WernerO   QUOTE (Axon @ Jul 31 2009, 21:28) Dr. Kun...   Aug 1 2009, 06:46
|- - 2Bdecided   QUOTE (Axon @ Jul 31 2009, 21:28) That se...   Aug 1 2009, 08:24
|- - rpp3po   I'm just coming back from vacation. Thanks for...   Aug 2 2009, 17:42
|- - Arnold B. Krueger   QUOTE (rpp3po @ Aug 2 2009, 12:42) But un...   Aug 3 2009, 01:24
|- - rpp3po   QUOTE (Arnold B. Krueger @ Aug 3 2009, 02...   Aug 3 2009, 01:42
|- - ncdrawl   QUOTE (rpp3po @ Aug 2 2009, 20:42) QUOTE ...   Aug 3 2009, 04:59
|- - krabapple   QUOTE (ncdrawl @ Aug 2 2009, 23:59) QUOTE...   Aug 3 2009, 07:57
|- - WernerO   QUOTE (ncdrawl @ Aug 3 2009, 04:59) Dr. K...   Aug 3 2009, 08:52
||- - Axon   QUOTE (WernerO @ Aug 3 2009, 02:52) QUOTE...   Aug 3 2009, 19:02
|||- - honestguv   QUOTE (Axon @ Aug 3 2009, 20:02) BTW, I f...   Aug 3 2009, 19:35
||- - ncdrawl   QUOTE (WernerO @ Aug 3 2009, 03:52) we do...   Aug 8 2009, 00:03
|- - honestguv   > Dr. Kunchur will be posting confutations in f...   Aug 3 2009, 08:54
|- - andy_c   Regarding my earlier post about the lack of second...   Aug 3 2009, 17:34
- - benski   I need to do further reading to do a full refutati...   Aug 3 2009, 20:10
|- - benski   Also, for his FAQ example of two peaks separated b...   Aug 3 2009, 20:24
|- - WernerO   QUOTE (benski @ Aug 3 2009, 21:24) two pe...   Aug 3 2009, 20:56
||- - Axon   QUOTE (WernerO @ Aug 3 2009, 14:56) QUOTE...   Aug 3 2009, 21:04
||- - benski   QUOTE (WernerO @ Aug 3 2009, 15:56) QUOTE...   Aug 3 2009, 21:22
|||- - WernerO   QUOTE (benski @ Aug 3 2009, 22:22) Please...   Aug 4 2009, 08:11
|||- - benski   QUOTE (WernerO @ Aug 4 2009, 03:11) QUOTE...   Aug 4 2009, 14:34
||- - honestguv   QUOTE (WernerO @ Aug 3 2009, 21:56) But t...   Aug 3 2009, 21:47
||- - benski   QUOTE (honestguv @ Aug 3 2009, 16:47) QUO...   Aug 3 2009, 22:04
||- - honestguv   QUOTE (benski @ Aug 3 2009, 23:04) They a...   Aug 3 2009, 22:49
|- - 2Bdecided   QUOTE (benski @ Aug 3 2009, 20:24) Also, ...   Aug 3 2009, 22:05
- - Canar   I just had a random thought about this and I wante...   Aug 4 2009, 02:41
|- - andy_c   Well, the 4.7us time constant does decrease the le...   Aug 4 2009, 02:57
|- - andy_c   Here's another thing I noticed in his test app...   Aug 4 2009, 14:23
||- - Arnold B. Krueger   QUOTE (andy_c @ Aug 4 2009, 09:23) Here...   Aug 13 2009, 12:56
|- - Pio2001   Hello, I've just read the first and third arti...   Apr 18 2010, 23:07
|- - C.R.Helmrich   QUOTE (Pio2001 @ Apr 19 2010, 00:07) Ther...   Apr 18 2010, 23:56
|- - Arnold B. Krueger   QUOTE (Pio2001 @ Apr 18 2010, 18:07) QUOT...   Apr 19 2010, 14:49
- - ultrasonic   QUOTE (rpp3po @ Aug 3 2009, 02:42) QUOTE ...   Jan 2 2010, 05:09
|- - Woodinville   QUOTE (ultrasonic @ Jan 1 2010, 20:09) QU...   Jan 2 2010, 05:28
||- - ultrasonic   QUOTE (Woodinville @ Jan 2 2010, 06:28) Q...   Jan 2 2010, 05:41
||- - Arnold B. Krueger   QUOTE (ultrasonic @ Jan 1 2010, 23:41) QU...   Jan 2 2010, 06:15
|- - Arnold B. Krueger   QUOTE (ultrasonic @ Jan 1 2010, 23:09) QU...   Jan 2 2010, 06:01
|- - ultrasonic   QUOTE (Arnold B. Krueger @ Jan 2 2010, 07...   Jan 2 2010, 06:37
|- - Arnold B. Krueger   QUOTE (ultrasonic @ Jan 2 2010, 00:37) QU...   Jan 2 2010, 06:52
|- - Woodinville   QUOTE (ultrasonic @ Jan 1 2010, 21:37) Op...   Jan 2 2010, 10:29
||- - Arnold B. Krueger   QUOTE (Woodinville @ Jan 2 2010, 04:29) B...   Jan 2 2010, 13:24
|- - krabapple   QUOTE (ultrasonic @ Jan 2 2010, 00:37) Op...   Jan 3 2010, 06:43
- - Woodinville   It is interesting to note that now the same people...   Jun 15 2010, 19:31
- - Arnold B. Krueger   QUOTE (Woodinville @ Jun 15 2010, 14:31) ...   Jun 16 2010, 11:09
- - Paulhoff   QUOTE (Woodinville @ Jun 15 2010, 14:31) ...   Jun 16 2010, 12:33
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