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In Reply to: RE: 44.1 kHz shown scientifically to be inadequate posted by Werner on July 29, 2009 at 22:40:02
Werner wrote:
Methinks the two above quotes are rather unscientific in their formulation.
The nits you pick at are undoubtedly present (i.e. some might find the text a little bit ambiguous, especially if they are so minded) but to complain of Kunchar’s writing in this context is a bit like complaining that, OK, that Stephen Hawking fellow is fine at physics and all that - but he’s shite at football. I don’t think the meaning is that hard to fathom.
We don't need any scientific publications for that.
The point was made in a note aimed at audio forum members, not in a scientific publication.
There were no experiments involving 'sharp peaks separated by 5us'. The auditory relevance of 44.1kHz not resolving two such peaks was not proven at all. That proof was not even on the agenda.
I don’t read Kunchar’s “FAQ” as suggesting that the point has been “proved”, rather that it is a logical consequence of his results. You suggest as much in the previous paragraph of your post (“We don't need any scientific publications for that”).
Again, you seem to be complaining of possible ambiguities in a text aimed at a lay audience rather than examining the experiments themselves. The latter strikes me as a more fruitful route. I don’t want to get into “quote swapping” but in the paper describing the low-pass filtering experiment, the phenomenon is described thus (“Procedure”, para 1):The control tone was perceived to have a sharper or brighter timbre whereas the filtered one had a duller quality (no difference in loudness was perceived except for the largest setting of t=30 μs).
Note that this is for differences in a stimulus (input signal) that are so minute that they had previously been dismissed by one and all as completely imperceptible. No one in the field had even felt the need to construct apparatus competent to measure them.
Now that their perceptibility has been established, we can agree that RBCD recordings are inherently unable to reproduce that level of detail. A technology now 30 years old does not, in fact, capture “perfect sound forever”. It’s good - but it’s not perfect.
Kunchar points that out and all hell breaks loose. He doesn’t suggest that we have to dump our CD collections. My DAC samples at 44.1 kHz only but I’m not planning to throw it in the sea (certainly not at that price). And so on.
But I can readily see how these findings provide strong support for those who consistently report that better quality sound is provided by good recordings made at higher resolutions.
It seems almost self-evident that the ultra-fast rise times encountered in percussive transients, the female voice and so on push RBCD to its limits. I just cannot see what the fuss is about.
I’m sorry but I don’t understand your points about cellphones and about satellites not getting lost or why the points are relevant. Nor do I know who JJ is. All that’s probably my fault.
Dave
Follow Ups:
"Again, you seem to be complaining of possible ambiguities in a text aimed at a lay audience rather than examining the experiments themselves. The latter strikes me as a more fruitful route"
I have been reading and rereading the two initial papers, with the two experiments, for about a month now.
The papers describe experimental results that, assuming no mistake was made, indicate that:
1) people can discern when two vertically stacked loudspeakers replaying a continous 7kHz squarewave are misaligned in depth down to a distance of 2mm (~5us)
2) ... when a monophonic headphones feed of a continuous 7kHz triangle is first-order low-pass filtered with a time constant down to 5 us.
Kunchur claims that all trivial mechanisms for distinction (i.e. as presently in the knowledge on auditory perception) have been accounted for and were found each to be below the JND threshold at the respective levels and frequencies. In other words: differences are detected and this
through a hitherto unknown mechanism.
Fine.
These two items, and only these two, are the basis of all further argument.
Now please tell me: how follows from 1) and/or 2) that a 44.1kHz sampling system is insufficient?
And tell me further: how follows from 1) and/or 2) that an audio coding system has to be capable of keeping separated two short impulses spaced 5us apart in time?
These are two claims made in the papers and/or the later FAQ, but I fail to see the connection, I fail to see how this is 'a logical consequence of his results' when the experiments did not involve a 44.1kHz sampling system, did not involve bandwidth limiting of the stimuli, and did not involve pulses spaced 5us apart.
This is a sincere question. Maybe I don't see the connection because
I'm stupid, ignorant, or wrongly educated. I'd like to know.
--
As for the FAQ being for laypeople: inaccuracy in terminology never ever brings any benefit.
bring bac k dynamic range
The relevance of the two pulse experiment is to the necessity of precise speaker alignment. (From the anecdotal story, this is what started Kunchur down his research path.)
The square wave test shows that a band limited 20 kHz channel is not aurally transparent. This would be a conclusive proof that a 40 kHz sampling rate is not adequate. By itself it is not conclusive proof that a 44.1 kHz LPCM system is transparent, but it strongly suggests it. What it definitely does is prove that the bandwidth of the human hearing system is not accurately characterized by the detection threshold of high frequency sine waves. Since it is these numbers that are frequently used to "prove" that 44.1 kHz suffices, what Kunchur has done is to refute of these proofs. Had Kunchur used a test frequency of 7351 Hz instead of 7000 Hz then he would have conclusively proven that 44.1 kHz LPCM is not adequate (subject of course to errors in experiment design, execution and analysis).
Informally, Kunchur has demonstrated that simplistic models of human hearing are not adequate to describe reality, and therefore that simplistic engineering approximations in the design of audio equipment may not be appropriate when designing the highest quality equipment.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
"Had Kunchur used a test frequency of 7351 Hz instead of 7000 Hz then he would have conclusively proven that"
Then again, the very outcome of the experiments might have been different.
But IMO the experiments should be redone, at 8kHz.
bring bac k dynamic range
If I were a betting man, I would bet that many if not most of the subjects would pass the test at a slightly higher frequency, given that they all passed the 7 KHz test. Not sure how far a bet I would place.
Speaking as an engineer, I would agree that the test should be repeated at 8 kHz. Or perhaps 8001 Hz. :-)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
"Informally, Kunchur has demonstrated that simplistic models of human hearing are not adequate to describe reality, and therefore that simplistic engineering approximations in the design of audio equipment may not be appropriate when designing the highest quality equipment."
More accurately, Kunchur has demonstrated that one simplistic model of human hearing yields different results than another simplistic model of human hearing. What he has NOT demonstrated, what his tests do not even imply, is anything meaningful about the complex models that are humans listening to real music through real, complex, audio reproduction systems.
That requires controlled, unsighted listening tests.
P
And what is an even greater leap, stretch, whatever...is the idea put forth in this thread that this study provides evidence, much less proof, that redbook is inadequate, or even distinguishable from higher rez formats. There are no audio systems in this study, not even any complete speaker systems, no music. This provides evidence that listeners can hear a variance in alignment between two identical drivers playing a square wave. Nothing more.
All the rest is wild speculation fueled by wishful thinking. I'm not saying there is no audible difference between redbook and hi-res. I'm just saying that this study takes us no closer to settling that debate.
This one, while it may make many uncomfortable, does:
http://www.google.com/url?sa=t&source=web&ct=res&cd=5&url=http%3A%2F%2Fdrewdaniels.com%2Faudible.pdf&ei=OrJxStOCPJOxtgf0-pWNBA&usg=AFQjCNHv8OtMKvwB9x8GX78tugq--0IChw
Multiple systems, multiple rooms, many listener groups of varying expertise and "listening skills," hundreds of trials...and relatively the same results over and over again. Though I'm sure we'll find reasons to invalidate its conclusions. We always do.
P
nt
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