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TAS at it again: bit-identical sources sound different. They just do.
post Dec 31 2011, 21:13
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Seen today on the Hoffman forum:

"In the latest Absolute Sound magazine there is an article on computer audio which claims (get this):

2 bit identical files on a hard drive, played back with JPlay (which reads hard drive to memory, then plays from memory), sound different. One file was ripped at half the speed of the other, both with JRiver, both confirmed with AccurateRip"

I haven't read the TAS article, but I followed up online and found one of its authors responding to queries about it, on another forum. Here's what he says:

As one of the authors of this article, let me make a few comments. First we have taken some pains to describe our methods in detail in order to encourage readers to repeat our tests for themselves. Only then can they be in a position to dispute or confirm our findings. Opinions don't really count for much. Experimental results are more compelling.

In the quote cited by bramankp, we agree that one can make copies that are truly "identicle" but one cannot conclude that they therefore must sound the same. There are many factors that can change the sound between the information storage source and the DAC. For example, compare identical music files played back from an optical drive, a defragmented hard drive, and a memory stick: they will all sound different. Bits are bits all right, but time- and amplitude-based jitter mechanisms can account for many of the sonic differences we report.

To rossop: See Part 3 of our article in TAS #220 on FLAC. There are many sources and reasons why FLAC and WAV sound different, sometimes to a disturbingly large degree.


His other replies further down that thread are no more convincing,e.g

Lets make sure we are talking about the same experiment first. Using JRMC, under ripping options, there is a sub-menu for read speed: 1x, 2x, 4x, 8x, 16x (version 15 of the software). This is what we were testing. As an aside, it is an Interesting question to ask why the manufacturer includes this option in their software. Second, our hearing sensitivity and acuity was highly conditioned after listening to the same test tracks over and over again for 8 months. Third, I have over 30 years of professional industry listening training. Fourth, our auditioning system was optimized with respect to power cabling, digital cabling, AC grounding, vibration control, and speaker resolution. If your situation is not the same, then you have not replicated our experimental conditions exactly. I contend that if the differences are hearable on any system, they are not meaningless, but rather indicate a real effect regardless of whether they can be heard in all systems or just select systems. And the history of science and engineering includes many examples of disputed concepts being eventually proven correct. If you think the results in Part 2 are outrageously wrong, wait until you read what we have to say about FLAC files in Part 3.

On the other hand, there are criticisms that can be made of our procedures. For example, testing was usually conducted under single, not double blind conditions. Our results lack proper statistical rigor; generally speaking, we looked to replicate our results on two different systems and duplicate our tests at least once. It is also the reason why these results were submitted for publication to TAS and not the JAES. For the record, we did employ listening panels and numerous replications (at least 4) for what we felt were going to be the most controversial findings. In the case of the particular experiment we are speaking about, similar results were obtained some time ago with an independent computer and software and at an independent time. Had we tried to repeat everything we did in triplicate with at least 2 weeks intervals between listening tests, we probably would not have lived long enough to complete this study, or at least would no longer be married.

As we enter 2012, I want to say Thank you, HA, for being an antidote to audiophile diseases like TAS.

This post has been edited by krabapple: Dec 31 2011, 21:15
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post Jan 9 2012, 10:38
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Actually, to be serious, there might be a tiny bit of interest in the article. Let us assume the auditory differences are real. Now...

Say, for instance (I didn't read the article because of the premise) that these listening tests were through speakers. Ok, what if the humidity changed (as it does often enough to be detected), did this account for the change in sound? Possibly. Did the uncompressed and compressed files get flip-flopped enough to take this in account? Was the tests followed up by headphone listening tests? Did they measure the temperature of the amplifier to take into account heat variances (since audiopholes seem to favor tube amps) to make sure the final stage did not introduce these differences? Oh wait, it was already stated up-front that the tests were not even double-blind, let alone all the other factors they may exist after the audio leaves the DAC.

I guess it seemed obvious to some people, but I had to put it writing.

Happy New Ear![sp]

"Something bothering you, Mister Spock?"
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Posts in this topic
- krabapple   TAS at it again: bit-identical sources sound different. They just do.   Dec 31 2011, 21:13
- - benski   Not that there's an ounce of sense in these pe...   Dec 31 2011, 22:09
- - Carledwards   It may be useful to remember that these magazines ...   Dec 31 2011, 22:26
- - Speedskater   Another audio forum has a thread on the magazine a...   Jan 1 2012, 00:39
|- - krabapple   QUOTE (Speedskater @ Dec 31 2011, 18:39) ...   Jan 1 2012, 20:05
- - Wombat   They just are starting a new market indeed and bre...   Jan 1 2012, 02:39
- - Goratrix   And another one of those threads over at the SH fo...   Jan 1 2012, 11:19
- - db1989   Wow, this is absolutely terrible. QUOTE As one of...   Jan 1 2012, 16:49
- - kraut   QUOTE for so many reasons. One of them to keep yo...   Jan 1 2012, 18:58
- - JimH   While you guys get a lot of things right, maybe ev...   Jan 2 2012, 01:46
|- - krabapple   QUOTE (JimH @ Jan 1 2012, 19:46) While yo...   Jan 2 2012, 03:24
|- - Stereoeditor   QUOTE (JimH @ Jan 1 2012, 20:46) I don...   Jan 2 2012, 15:02
||- - Arnold B. Krueger   QUOTE (Stereoeditor @ Jan 2 2012, 09:02) ...   Jan 11 2012, 15:30
|- - Arnold B. Krueger   QUOTE (JimH @ Jan 1 2012, 19:46) While yo...   Jan 11 2012, 15:47
- - kraut   QUOTE (JimH @ Jan 1 2012, 17:46) While yo...   Jan 2 2012, 02:25
|- - Nessuno   QUOTE (kraut @ Jan 2 2012, 02:25) QUOTE F...   Jan 2 2012, 09:44
- - db1989   QUOTE (JimH @ Jan 2 2012, 00:46) While yo...   Jan 2 2012, 02:36
- - Destroid   May I interrupt the logical arguments and ask if t...   Jan 2 2012, 10:05
- - smok3   QUOTE Do bits have memory like homoeopathic water?...   Jan 2 2012, 11:10
|- - Kujibo   QUOTE (smok3 @ Jan 2 2012, 02:10) serious...   Jan 2 2012, 22:55
|- - JimH   QUOTE (Kujibo @ Jan 2 2012, 15:55) I have...   Jan 3 2012, 01:58
- - john33   It just beggars belief that anyone with even a bas...   Jan 2 2012, 13:45
|- - Porcus   QUOTE (john33 @ Jan 2 2012, 13:45) bit-id...   Jan 3 2012, 15:11
|- - pdq   QUOTE (Porcus @ Jan 3 2012, 10:11) Well, ...   Jan 3 2012, 15:16
|- - john33   QUOTE (pdq @ Jan 3 2012, 14:16) QUOTE (Po...   Jan 3 2012, 15:38
|- - Porcus   QUOTE (john33 @ Jan 3 2012, 15:38) QUOTE ...   Jan 3 2012, 19:09
- - JimH   Hi John, I can understand why it took a long time ...   Jan 2 2012, 17:39
|- - db1989   QUOTE (JimH @ Jan 2 2012, 16:39) In the e...   Jan 2 2012, 17:57
|- - JimH   QUOTE (db1989 @ Jan 2 2012, 10:57) Audiop...   Jan 2 2012, 20:15
- - Deep_Elem   So when I copy audio files from one part of my sys...   Jan 2 2012, 18:47
|- - Juha   QUOTE (Deep_Elem @ Jan 2 2012, 21:47) So ...   Jan 2 2012, 19:03
- - Speedskater   The same two authors did publish a 7 page article ...   Jan 2 2012, 19:10
- - Wombat   Me doesn´t know much but there are many that know ...   Jan 2 2012, 19:43
- - john33   While I am all in favour of freedom of speech, exp...   Jan 2 2012, 20:26
- - ramicio   These people who keep pushing this ultra expensive...   Jan 2 2012, 20:37
- - .halverhahn   Come on, please be serious. Audiodata is a magic t...   Jan 2 2012, 22:58
- - andy o   QUANTUM! I win.   Jan 3 2012, 01:23
- - greynol   ...if we could only dismiss this thing as an accid...   Jan 3 2012, 02:58
- - SoAnIs   I should mention that the same file played back at...   Jan 9 2012, 02:32
- - Destroid   Actually, to be serious, there might be a tiny bit...   Jan 9 2012, 10:38
- - Brother John   Destroid, you’re falling in the exact trap they ar...   Jan 9 2012, 19:37
- - Destroid   Yes, I think my above post was intended for those ...   Jan 9 2012, 20:20

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