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Topic: The Emperor's New Sample Rate (Read 63644 times) previous topic - next topic
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The Emperor's New Sample Rate

Reply #1
Good read. Thank you.

The Emperor's New Sample Rate

Reply #2
Some very interesting stuff in there. Two items that I can defintely concur with:

1) The higher sampling rates do not necessarily mean better sound. The primary reason IMO that DVD-A, DTS and SACD sound better is simply a better engineered recording. DTS rarely misses with their engineering quality. On the other hand I have SACDs that sound like crap and some that are excellent.

2) Room acoustics play a HUGE part in sound playback. I used to work for a company with a large RF testing chamber that was also acoustically anechoic. We put the speakers in there one weekend (JMLAB electras). the imaging was fantastic but the bass took on a very funny unnatural sound.

I have always been guided by the following 3 principles (which I borrowed)

1) Good speakers.
2) Lots of clean power amplification.
3) Good build quality.

My big disappointment is that with sagging music sales the recording companies make me pay an arm and a leg for something that should have been done right to begin with and worse yet sometimes the "audiophile" version is garbage.

The Emperor's New Sample Rate

Reply #3
I found the end of the article, talking about the sound changing by you moving just a few centimeters very interesting. It's something which most of us know and take for granted - but which is rarely taken into account in listening tests. It's the kind of argument which points out something which is forgotten because it is too obvious. Simple and trivial argument - huge consequences. Very interesting.
I am arrogant and I can afford it because I deliver.


The Emperor's New Sample Rate

Reply #5
Previous discussion about the study the article mentions:
http://www.hydrogenaudio.org/forums/index....c=57406&st=



Sadly, but not at all unexpectedly, the AA crowd will grasp at any straw they can, and retail whatever half-remembered anecdote they can, to remain in denial about ABX testing.

http://www.audioasylum.com/forums/prophead...ages/43478.html

http://db.audioasylum.com/cgi/m.mpl?forum=...ight=EBradMeyer

The Emperor's New Sample Rate

Reply #6
Very interesting article. It's nothing new, only confirming a couple of tests done here where a 'hi-definition' sample could not be ABXed against a properly dithered one.

I guess the only reason to buy a 'high-definition' media is to have a source that is mastered towards audiophiles, with full dynamic range and such, because there are no quality gains to these other formats.

The Emperor's New Sample Rate

Reply #7
What surprises me about that article is that so many people in the "pro" audio world still believes that hi-res audio is clearly better than standard reedbook CD audio.

About the author noting the audible difference possibly due to the superior time resolution of high-res audio, he and the paper he cites are just plain wrong, which again, puzzles me. Wrong in two ways. First, it has been determined experimentally that humans can detect ITDs (interaural time delays) up to 10 us, not 15 ms, as he notes. And second, time resolution on sampling systems is not just 1/fs, 1/44100 in case of CD, but more like 1/(fs*nº of discrete levels), or 1/(44100*65535), which is thousands of times smaller than the 10 us detectable under best circumstances. So CD is more than adequate in this sense.

The Emperor's New Sample Rate

Reply #8
What surprises me about that article is that so many people in the "pro" audio world still believes that hi-res audio is clearly better than standard reedbook CD audio.

About the author noting the audible difference possibly due to the superior time resolution of high-res audio, he and the paper he cites are just plain wrong, which again, puzzles me. Wrong in two ways. First, it has been determined experimentally that humans can detect ITDs (interaural time delays) up to 10 us, not 15 ms, as he notes. And second, time resolution on sampling systems is not just 1/fs, 1/44100 in case of CD, but more like 1/(fs*nº of discrete levels), or 1/(44100*65535), which is thousands of times smaller than the 10 us detectable under best circumstances. So CD is more than adequate in this sense.
Indeed. I think the whole time resolution thing is a bit of a red herring anyways. Saying "frequencies above 22kHz are audible given XdB of SNR" and "44.1kHz sampling has inadequate time resolution" are equivalent statements. Seperating the concepts of SNR and bandwidth from the concept of time resolution is not possible.

The Emperor's New Sample Rate

Reply #9
And as I showed a while back, Red Book has a time resolution in the *low nanoseconds* anyway, well below the limits of audibility of time resolution.

You'd think that people who cared about such things would actually test it, or quote people who test it!

The Emperor's New Sample Rate

Reply #10
And as I showed a while back, Red Book has a time resolution in the *low nanoseconds* anyway, well below the limits of audibility of time resolution.

You'd think that people who cared about such things would actually test it, or quote people who test it!



I stumbled upon this paper today, presented by Ken Pohlmann at tape archivist's meeting a couple of years ago.  In the excerpt below, isn't he presenting much the same sort of argument that you debunked, in his mentions of interaural difference and preservation of musical transient?   


http://www.clir.org/activities/details/AD-...rs-Pohlmann.pdf

Emphases mine.  NB I have seen the Woszczyk 2003 preprint and he too makes the same arguments (without any new listening test data).


Quote
Sampling Frequency
Generally, sampling frequencies of 44.1, 48, 96, and 192 kHz are used in high-fidelity
recording. The usable audio bandwidth is one-half the sampling frequency, so higher
sampling frequencies provide a wider audio bandwidth. This is potentially useful because
musical instruments can generate content with wide bandwidths; for example, a cymbal
might have response of 90 dB SPL (sound pressure level) beyond 60 kHz, and a violin
might have content beyond 100 kHz.

Even so, the use of high sampling frequencies such as 96 and 192 kHz may seem
unnecessary. In rare cases, a person may be able to hear frequencies to 24 or 26 kHz, far
below the cutoff frequencies of 48 and 96 kHz. In most cases, high-frequency hearing
response is below 20 kHz. Thus, for steady-state tones, the higher-frequency response
may not be useful. However, a high sampling frequency provides additional benefits
beyond wide audio bandwidth. It can be argued that high sampling frequencies improve
the binaural time response, leading to improved imaging in multichannel recordings. For
example, if short pulses are applied to each ear, a 15-?S difference between the pulses
can be heard, and that time difference is shorter than the time between two samples at 48
kHz. Some people can hear a 5-?S difference, which corresponds to the time difference
between two samples at 192 kHz. In theory, a high sampling frequency might improve
spatial imaging.


Similarly, higher sampling frequencies provide improved temporal response. For
example, the sampling interval at 44.1 kHz is 22.7 ?S; at 192 kHz, it is 5.2 ?S. Musical
instruments can generate transients with rise times of less than 10 ?S. As another
example, room reverberation comprises a large number of reflections arriving at high
rates. For example, reverberation might comprise 500,000 arrivals per second; spaced
regularly, this time interval is less than 2 ?S. Human subjects are sensitive to interaural
time delays of between 2 and 10 ?S. Subjects have differentiated between a regular pulse
train and one with deviations of 0.2 ?S.
Higher sampling frequencies clearly preserve
temporal response (Woszczyk 2003). In addition, higher sampling frequencies allow
greater latitude in the design of the anti-aliasing low-pass filter. For example, a lowerorder
slope may be employed, providing improved time-domain response; this is further
described below. Generally, high sampling frequencies can promote improved filter and
signal processing performance in the traditional audio (0 to 20 kHz) band. Ultimately,
because the limit of human hearing acuity is not yet known, the point of transparency of a
recording system cannot be known. In some cases, such as the conversion of monaural
speech recordings, a lower sampling frequency of 48 kHz may be used. However, for
highest audio fidelity, higher sampling frequencies of 96 or 192 kHz are recommended.

The Emperor's New Sample Rate

Reply #11
Quote
Human subjects are sensitive to interaural time delays of between 2 and 10 μS.
I hope they're sensitive to longer ones too!!!

Seriously 2us, where does he get that from?

And the 0.2us later on - are there any references?

10us is the usually quoted figure. I know where that came from (though don't have the reference to hand).

Of course any sampling rate is sufficient to preservse such inter-channel differences within the Nyquist bandwidth. Quantisation can impose a limit, but not anything relevant at 16-bits 44.1kHz! We've had this discussion several times before.

Cheers,
David.

The Emperor's New Sample Rate

Reply #12
First off, I am not an expert, however, it seems to me that there may be a 'flaw' in one of the conclusions of this study, if they only look at averages. One conclusion was that no one could tell between the two sample rates, but they don't mention how many particular individuals scored much higher than chance. If there were such individuals, then they, and they alone, would benefit from higher sampling rates. This makes sense if you consider that for there to be those who can't hear a difference, they must be conterbalanced by those who can hear a difference. To me all this study demonstrates is, yes, the majority of people can't tell and therefore don't need higher sampling rates. Personally, I think to satisfy my concerns, I'd like a study that tests many people looking for any who could discern a difference, and then further testing to see how good human hearing really is. Of course, if there's a flaw in my reasoning, please, don't hesitate in letting me know. 

As well, I'd just like to point out that as much as some people seem to need to justify spending money on audio, others seem to need to justify not spending money on audio. Personally, I don't care about justifications or, even other peoples' preferences; I'm only looking for what quenches my thirsty ears. 
Quis custodiet ipsos custodes?  ;~)

The Emperor's New Sample Rate

Reply #13
First off, I am not an expert, however, it seems to me that there may be a 'flaw' in one of the conclusions of this study, if they only look at averages. One conclusion was that no one could tell between the two sample rates, but they don't mention how many particular individuals scored much higher than chance. If there were such individuals, then they, and they alone, would benefit from higher sampling rates.



If I recall Meyer and Moran's paper correctly, they did retest initial 'high-scorers', who ended up doing no better than chance in multiple tests.  btw it's always better to read the actual primary research rather than dismissing it based on someone else's summary. You can buy the paper for $20 from JAES.  There's also
a website supplement to the paper 

http://www.bostonaudiosociety.org/explanation.htm

and Moran himself has posted here on HA in defense of the work.


Quote
Human subjects are sensitive to interaural time delays of between 2 and 10 ?S.
I hope they're sensitive to longer ones too!!!

Seriously 2us, where does he get that from?

And the 0.2us later on - are there any references?


I suspect he got them mostly from Woszczyk 2003, which itself turns out to be a review, rather than original research. 

Quote
10us is the usually quoted figure. I know where that came from (though don't have the reference to hand).

Of course any sampling rate is sufficient to preservse such inter-channel differences within the Nyquist bandwidth. Quantisation can impose a limit, but not anything relevant at 16-bits 44.1kHz! We've had this discussion several times before.


Which is why I find it curious that Ken Pohlmann, of all people, would be retailing these arguments.  EVen more curious is the schizophrenic nature of the paper, which offers these dubious arguments up front, but devotes a later section to emphasizing why double blind listening tests are necessary to confirm
differences.

The Emperor's New Sample Rate

Reply #14
btw it's always better to read the actual primary research rather than dismissing it based on someone else's summary. You can buy the paper for $20 from JAES.

Sure, it's better, but hardly required. As for dismissing the study, I did no such thing. I'm afraid it appears that you've completely overstated my position; perhaps you didn't read my 'comment' carefully?. Oh, and as for physically purchasing the paper, are you suggesting that unless one has purchased the study from "JAES", one has no right to comment on it in this thread? 

If I recall Meyer and Moran's paper correctly, they did retest initial 'high-scorers', who ended up doing no better than chance in multiple tests....and Moran himself has posted here on HA in defense of the work.

Speaking of proof, please, can you provide a link?
Quis custodiet ipsos custodes?  ;~)

The Emperor's New Sample Rate

Reply #15
Of course any sampling rate is sufficient to preservse such inter-channel differences within the Nyquist bandwidth. Quantisation can impose a limit, but not anything relevant at 16-bits 44.1kHz! We've had this discussion several times before.
Yes, we have. It's pretty well established theory, and well recognised and used in many fields (such as radar signal processing).

From http://www.bostonaudiosociety.org/explanation.htm:
Quote
One of the authors, using a short repeated section of room tone on the Hartke disc mentioned above, obtained a positive result (15/15) at a gain of only 10 dB above our standard level. This setting produced sound levels clearly higher than those at the site, as the peak levels for this small vocal/percussion ensemble would have been 111 dB SPL on the loudest part of the disc.

This is an interesting result. In fact, that whole page is well worth a read.

The Emperor's New Sample Rate

Reply #16
This makes sense if you consider that for there to be those who can't hear a difference, they must be conterbalanced by those who can hear a difference.

This is an amazing use of logic and could have important application in other areas as well.

For instance, for there to be people who have never met aliens, they must be counterbalanced by those who have met aliens?

The Emperor's New Sample Rate

Reply #17

This makes sense if you consider that for there to be those who can't hear a difference, they must be conterbalanced by those who can hear a difference.

This is an amazing use of logic and could have important application in other areas as well.

For instance, for there to be people who have never met aliens, they must be counterbalanced by those who have met aliens?

Hehe.

The main flaw in 2tecs thinking is that because he isn't that experienced, he doesn't know and understand yet, that it is impossible to prove the non-existence of something anywhere in the world. But it is possible to prove the existence of something at specific locations in the world. This does NOT mean, that therefore something must exist somewhere in the world - it just means that you cannot test it. This is because we cannot look everywhere simultaneusly - we cannot test everything everywhere at the same time. Therefore, nonexistence of something regardless of location, is impossible to prove.... but it can be estimated: Probabilities. When in theory something doesn't exist, and besides of various tests and widespead awareness about the topic, no one succeeds in proving one single existence of the effect.... then it is reasonable to "asume", that it doesn't exist until proven otherwise. We have no proof that higher samplerates are unperceivable - but we also have zero evidence that it is perceivable - therefore we can ignore the issue until it starts to matter. We have no proof that the FSM doesn't exist - but we also have zero evidence that it exists - therefore we can ignore the issue until there is evidence. Thus, the burden of proof is always on the person who makes a claim about the existence of something.

And there is more to it: If apparently it is very difficult to prove the existence of something - thus, if its proposed effects seem very difficult to notice - then it is reasonable to asume, that even if it exists, its significance is very low. But if the significance of higher samplerates for listening are very low IF they exist..... then whats the point in spending all the resources for recording, storing, reproducing them? This makes higher samplerates look even more uninteresting, because it means: Higher samplerates do not seem to be perceivable - and even if they were perceivable by someone, then it is probable that in the majority of cases they are insignificant. Bummer!
I am arrogant and I can afford it because I deliver.

The Emperor's New Sample Rate

Reply #18
btw it's always better to read the actual primary research rather than dismissing it based on someone else's summary. You can buy the paper for $20 from JAES.

Sure, it's better, but hardly required. As for dismissing the study, I did no such thing. I'm afraid it appears that you've completely overstated my position; perhaps you didn't read my 'comment' carefully?. Oh, and as for physically purchasing the paper, are you suggesting that unless one has purchased the study from "JES", one has no right to comment on it in this thread? 



If I recall Meyer and Moran's paper correctly, they did retest initial 'high-scorers', who ended up doing no better than chance in multiple tests....and Moran himself has posted here on HA in defense of the work.

Speaking of proof, please, can you provide a link?





First..if you're going to attempt sarcasm, it's best not to display ignorance instead -- it's 'JAES', as I wrote,  which stands for the Journal of the Audio Engineering Society. 

Second, Moran posted to this HA thread about the paper which I guess you were unable to call up by searching for 'moran' , like I just did.

Third, I misremembered.  In fact, there was no retesting...because no subject achieved a score where p< 0.05, unless levels were jacked up to abnormal levels.  Quoted from the paper (emphasis mine):

Quote
The test results for the detectability of the 16/44.1 loop
on SACD/DVD-A playback were the same as chance:
49.82%. There were 554 trials and 276 correct answers.
The sole exceptions were for the condition of no signal
and high system gain, when the difference in noise floors
of the two technologies, old and new, was readily audible.

As the tests progressed, we repeatedly sorted the data
for correlations with age, sex, upper frequency hearing
limit, or experience. No such correlations have emerged.
Specifically, on music at normal levels as defined here,
audiophiles and/or working recording-studio engineers got
246 correct answers in 467 trials, for 52.7% correct. Females
got 18 in 48, for 37.5% correct. Those subjects able
to hear tones above 15 kHz got 116 in 256 trials, for 45.3%
correct; listeners aged 14–25 years old (who were, as it
turned out, the same group), also got 116 correct in 256
trials, 45.3%. The “best” listener score, achieved one
single time, was 8 for 10, still short of the desired 95%
confidence level. There were two 7/10 results. All other
trial totals were worse than 70% correct.


Furthermore, none of the more elaborate and expensive
playback systems (for which the subjects were all dedicated
amateur audiophiles, active students in a professional
recording program, and/or experienced working
professionals
) revealed detectable differences on music,
again at levels as defined previously.

The Emperor's New Sample Rate

Reply #19
There is something else to take into account: To a limited degree, HA-Members have already tested ultra-high frequency perceivability en masse, simply by ABXing lossy encoders. Lossy encoders use a lowpass exactly because it is asumed that people cannot hear it - at least on normal equipment. If trained ABXers cannot hear 19-22khz, then why should they be capable of hearing stuff above 22khz? In other words, we have already tested this issue en masse, simply by ABXing between lossless and lossy. Test it yourself: just lowpass a lossless file at about 18khz... then try to ABX it on your best equipment.
I am arrogant and I can afford it because I deliver.

The Emperor's New Sample Rate

Reply #20
There is something else to take into account: To a limited degree, HA-Members have already tested ultra-high frequency perceivability en masse, simply by ABXing lossy encoders. Lossy encoders use a lowpass exactly because it is asumed that people cannot hear it - at least on normal equipment. If trained ABXers cannot hear 19-22khz, then why should they be capable of hearing stuff above 22khz? In other words, we have already tested this issue en masse, simply by ABXing between lossless and lossy. Test it yourself: just lowpass a lossless file at about 18khz... then try to ABX it on your best equipment.
So you're saying that if you can't ABX lossy from lossless, you won't be able to ABX 'standard' digital audio from 'high-res' digital audio, either? (Or is this just one aspect of 'high-res' digital audio?)

The Emperor's New Sample Rate

Reply #21
So you're saying that if you can't ABX lossy from lossless, you won't be able to ABX 'standard' digital audio from 'high-res' digital audio, either? (Or is this just one aspect of 'high-res' digital audio?)

I am saying that if we cant ABX something which implements a lowpass, then why should we be able to ABX freqs which are even higher than that lowpass?

To simplify it:

IF for example we cannot ABX the removal of 18-22khz, then why should we be able to ABX the removal of 22-48khz? AFAIK, the human hearing curve doesnt go up the higher the freqs, but instead down.
I am arrogant and I can afford it because I deliver.

The Emperor's New Sample Rate

Reply #22
There is something else to take into account: To a limited degree, HA-Members have already tested ultra-high frequency perceivability en masse, simply by ABXing lossy encoders. Lossy encoders use a lowpass exactly because it is asumed that people cannot hear it - at least on normal equipment. If trained ABXers cannot hear 19-22khz, then why should they be capable of hearing stuff above 22khz? In other words, we have already tested this issue en masse, simply by ABXing between lossless and lossy. Test it yourself: just lowpass a lossless file at about 18khz... then try to ABX it on your best equipment.



While the mass cannot generally ABX high-quality mp3s from source -- myself included in the mass -- a very few trusted HA posters (ones tending to be involved in LAME development)  have reported the ability to ABX of the highest-quality lossy encodes on a regular basis.  Don't know whether that's because of HF cut, or some other artifact.

The Emperor's New Sample Rate

Reply #23
While the mass cannot generally ABX high-quality mp3s from source -- myself included in the mass -- a very few trusted HA posters (ones tending to be involved in LAME development)  have reported the ability to ABX of the highest-quality lossy encodes on a regular basis.  Don't know whether that's because of HF cut, or some other artifact.

That might be a little exaggerated. I think the few posters you are referring to can regularly ABX select tracks, but I suspect that most tracks even they are not able to ABX a high-quality encode. And the ones that they are able to ABX they usually report such things as pre-echo, warbling, sandpaper sounds, things like that. I don't recall any case where they report it as being "less bright" or something similar that would indicate loss of high requencies.

The Emperor's New Sample Rate

Reply #24
IF for example we cannot ABX the removal of 18-22khz, then why should we be able to ABX the removal of 22-48khz?
I don't think you can make that leap. Lots of CD content rolls off above 20kHz, while some encoders keep everything up to about 19kHz, so the loss is tiny. The loss of 22-48kHz is huge in comparison. I'm not saying it's audible - I'm saying your argument is not safe.

IIRC there was one individual who could ABX a 19kHz low pass filter. This was back in the r3mix forum days, so you won't find the post on HA.

Cheers,
David.