24/96 digitalization - can it be audible
Reply #28 – 2011-06-21 19:26:34
Just to be clear, this is all about an average score? All the individual scores failed to reach the statistical significance threshold? Yes - but keep in mind that due to low number of trials and due to correction for multiple participants, the threshold for individual analysis was very high - 12/13 =92.3%. Unfortunately we could not run more trials, with 50 trials and 10 participants just 74% (37/50) would suffice.82/130. Assuming you didn't cherry pick the data, I reckon it's fair to take that as one block. I did not cherrypick. All data from all participants are used, exactly as reported in the asnwer cards. Actually, one of the top-scorer's errors was a correction from initially correct response, had he not corrected, he would pass the individual statistical threshold. But we take his (wrong) correction as final. I refrained from taking the data as one block as you suggested, because they were 13 submeasurents (trials) in 10 measurements (participants), and assuming individual differences in perceptual abilities, the 13 submeasurements within each of 10 participants were not independent. Anyway, the 95% confidence interval of the 82/130 proportion is 0.5452 to 0.7089 (or 0.5413 to 0.7125, using another method), it does not include 0.5, so would I consider the proportion to be significantly different from 0.5.I'd be very worried about a 0.2dB level difference, and quite worried about clipping (depending on the content). Yeah, clipping is not good, and we should have avoided it. As i said though, there was very little of it, just a few cut of peaks over tens of seconds of recording. As of the level difference, are there any published data showing sensitivity to level differences <0.2 dB in complex/musical signals? Anyway, if this is significant, we would need a different A/D/A device, one that it is closer to ideal unity gainBut the multiple listeners issue is bothersome. Is there any possibility that the listeners influenced each other? This cannot be excluded, but there was no way to get access to the room and equipment for 10 individual sessions. We have no reports of such influence from the participants, but subconscious influence is theoretically possibleAlso, as far as applicability, we don't tend to listen to our hi-fi that way, with all that acoustic interference. What kind of acoustic interference are you referring to?- Level matching within 0.2dB is insufficient and could be well audible [...] It should be repeated with levels matched within 0.1dB and lowered input level to give really significant results. Again, I'd appreciate references that established jnd for intensity in complex signals to be <0.2 dBI'm no statistics expert but it seems like too little data. Have you tried flipping a coin 130 times instead and processing the results the same way? What kind of conclusion would you jump to if it gave you the same result? I believe this part has been taken care of properly without physically flipping a coing. That's what we have math for.