Part of this study refers to the redbook upper frequency cut. Also, as I understand, part of this study refers to the ABX methodology.
In my opinion, ABX tests and the statistical methodology that accompanies them are NOT DIRECTLY questioned in this experiment. Nevertheless, ABX tests are used to try to establish a difference or to establish the absence of a difference (similitude) among the way two reproduction machines can reproduce music. So we use sound samples as means of conducting these tests, then we proceed to the conclusion (are they similar or not). We knew _before_ this experiment that : - Frequency samples cannot be used to distinguish two reproduction machines using ABX tests. Explanation: A music message is a sum of primary (for instance: sinusoidal) sounds. This is similar to the way a D/A conversion works. One could think that if we can distinguish a difference using two frequency samples, then we can conclude that we can -logically- distinguish the resulting (as a sum) music. In fact, several tests (I participated myself in one of them) proved that we CANNOT distinguish two frequency-based sound samples reproduced by two different machines, even if we could distinguish (using the same ABX tests) these machines using normal (time-based) music samples. Why ? Simply because a human ear is NOT a linear measurement instrument. Not really a big discovery, some may say. Exactly: Oscilloscopes and other measurement instruments are much better than our ears. Conclusion: Never use frequency-based (primary) sounds to proceed to ABX tests: The results are irrelevant, the tests are void. But we have always thought that: - Duration samples (complex, but of a small duration) could be used to distinguish two reproduction machines using ABX tests. This experiment concludes that duration samples cannot be used to proceed to ABX tests, because the results _may_be_ irrelevant. Well what then ? What does it mean -may be- ? They are, or they are not ? In fact, as ABX tests use mathematical (statistical) methodology, the range rule apply: the measurement means MUST be absolute. No -maybe- is accepted, or the methodology is broken. Statistics need facts to work, not approximations. So, in fact, as this experiment establishes an approximation (or even -the not measurable possibility- of an approximation, if you are optimistic), the samples cannot be used anymore. Simple mathematics. So what ? No problem: It's enough to use longer, complex samples to validate the ABX tests, that's all. No problem, as I stated. On the other hand: any ABX test that doesn't use long, complex samples is void. We can't manipulate maths as we want, pity. :D -- Themis SB3 - North Star dac 192 - Denon 3808 - Sonus Faber Grand Piano Domus ------------------------------------------------------------------------ Themis's Profile: http://forums.slimdevices.com/member.php?userid=14700 View this thread: http://forums.slimdevices.com/showthread.php?t=54077 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
