Audibility of temporal smearing and time misalignment of acoustic signals

bonzo75

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This was posted by John Doe on the cable elevators thread in the Tweak section - though I would post it here for a broader read, a CGabriel suggested.

http://boson.physics.sc.edu/~kunchur/align.pdf
It is an article entitled "Audibility of temporal smearing and time misalignment of acoustic signals" by Milind N. Kunchur
from the Department of Physics and Astronomy, University of South Carolin

"Misalignment in timing between drivers in a speaker system and temporal smearing of signals in
components and cables have long been alleged to cause degradation of fidelity in audio reproduction."
 

Speedskater

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Sep 30, 2010
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The errors in Kunchur's papers and the resulting incorrect conclusions that they caused were well discussed some years ago.
 

CGabriel

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The errors in Kunchur's papers and the resulting incorrect conclusions that they caused were well discussed some years ago.

Do you have a link to the information that refutes his tests and conclusions? Were his tests replicated with different results? What group or individual replicated the tests?
 

Tony Lauck

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The errors in Kunchur's papers and the resulting incorrect conclusions that they caused were well discussed some years ago.

At the time I read many of these discussions, but my recollection is that none of these rose to the level of being even a partial refutation of Kunchur's results. Indeed, most of the discussion was by the usual players and was at the usual level of sloppy detail. I considered this to be a sad situation, and an example of why many serious scientists might well want to steer clear of audiophilia. I suggest starting with this file on Kunchur's web site:

http://boson.physics.sc.edu/~kunchur/papers/FAQs.pdf

I do not intend to go back and revisit all these discussions. However, if someone has any specific discussions, including still active web links, that they believe convincingly demonstrate a significant error in Kunchur's work, then let's see them.
 
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amirm

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Ok, I have done several internet search's and cannot find anything credible to refute Kunchur's experiments. The only thing I found is the usual forum squabbling between self ascribed "experts".

http://beta.stereophile.com/content/interesting-papers-1?page=10
I have not read that thread but member "J_J" is a world class audio expert and this is his area of specialty (he used to be an architect on my team at Microsoft and a member here): https://home.comcast.net/~retired_old_jj/

When I have time I will read through the thread but for now, just wanted to make sure we didn't mix him with average joe arguing on forums :).
 

CGabriel

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I have not read that thread but member "J_J" is a world class audio expert and this is his area of specialty (he used to be an architect on my team at Microsoft and a member here): https://home.comcast.net/~retired_old_jj/

When I have time I will read through the thread but for now, just wanted to make sure we didn't mix him with average joe arguing on forums :).

He clearly has knowledge and expertise. So we have two people with expertise. One of them does extensive research and formally presents his test procedure, test result and conclusions. Do you know what James' primary objection was to the Kunchur report?
 

amirm

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He clearly has knowledge and expertise. So we have two people with expertise. One of them does extensive research and formally presents his test procedure, test result and conclusions. Do you know what James' primary objection was to the Kunchur report?
My memory is hazy from a few years ago when this came to surface. I seem to recall he agreed with results of double blind tests but objected to extrapolating that to needing higher sampling rates to achieve that kind of timing accuracy as the paper attempts to do.
 

esldude

New Member
I remember two objections to interpreting his results. One is the same I believe as JJ's. Kunchur says you can't time a left and right signal if the difference is less than one sample period. This is not true. You can distinguish the timing difference between channels down into the less than 100 picosecond range with redbook. Even less timing shift with 24 bit signals.

Another objection with one version of his experiments was his saying JND's are 1 or so db. This is true in terms of hearing two sounds as being different loudness. It is known however signals that differ by as little as .2 db are perceived in blind testing. His use of 7 khz square waves and analog filters for ultrasonic harmonics meant the fundamentals had less than 1 db difference in the audible 7 khz tone. When the filters created about a .25 db difference or more they were picked blind. One has to wonder if it was merely the difference in level that was heard, and the level of overtones were relatively irrelevant. I don't have it now, but at one point the filters were shown, and the level of discernment tracks just about what you would expect testing people for nothing more than simply a small sound level difference.

I have seen better discussion scattered about various forums, but this is one from the Audio Critic. No it is not to the level of proper refutation in publication of a journal.

http://www.reddit.com/r/audiophile/comments/1x13rs/

Most of the forum discussions are nearly futile to slog through. You do have people like JJ and others worth listening to and many more not.

Another question in my mind was the use of 7 khz squarewaves. I know it would be 7 khz with all odd harmonics and therefore 21 khz for the first odd harmonic is over 20 khz. The reason I question it is with pure tones timing between ears is at its best around 800 hz and below. There is not much of it above 2 khz on pure tones. Multi-tones and music can sometimes get grouped by our hearing and timed like lower tones, but you wouldn't expect 7 khz to work well at all for a test of timing in human hearing.
 
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