cliveb;372009 Wrote: > I appreciate that your comment was aimed at Pat, but might I make a > comment? > > Everyone seems to be getting at Pat without appreciating what he's > actually trying to say. As I read it, he's merely speculating that > perhaps in the real world, except in gross situations, the effects of > jitter are not audible. Others have stated it is, and all he's asking > for is references to some proper research to back up those claims. > > You have kindly provided a link to an article which presumably you > believe supports the position that jitter is audible. I read the > article and it strikes me that (among other things): > > - It explains what jitter is. (Many people, Pat included, already know > what it is). > > - It has some interesting technical measurements with some alarming > looking scope shots. Whether these measurements are actually relevant > to the question in hand is not at all clear. > > - It discusses jitter's effect on the reproduced sound. This is done > with listening tests - which of course is the only way to detect any > audible effect. At no point in the article do they claim the listening > tests were done blind. Call me an old cynic, but don't you think it's > likely that if the test *was* blind, they would have mentioned it? My > speculative conclusion: the tests were not blind. So, given the > well-documented flaws of sighted comparison, shouldn't we treat them > with some degree of skepticism? Especially in the light of the article > having been published by a vendor of rather expensive audio DACs and > such like (ie. perhaps they have some kind of vested interest)? > > Meanwhile, Benjamin and Gannon demonstrated back in 1998, *using blind > listening tests*, that jitter less than 20nS was inaudible on music > material. > > And in 2004, Ashihara et al demonstrated, *using blind listening > tests*, that not one single listener in their panel of 23 people could > discriminate jitter of less than 250nS. Granted their test used random > (ie. uncorrelated) jitter, and this can be expected to be less audible > than correlated. But some people here seem to be claiming that jitter > around the 200pS region is audible. That's 3 orders of magnitude > smaller. It frankly stretches the bounds of credulity.
Good points. If I understand your first point, you and Pat are asking for someone to either perform a blind test showing that very low jitter rates are audible, or to be able to point to an acceptable research document that shows a blind test (or other suitable scientific method) was done that proved or disproved that claim. That said, few who post on this forum (or I would wager, any hobby forum) will be equipped (or motivated) to do the research first-hand, so we're really left with locating publications to back up competing claims for or against. Dueling reference works - woohoo! Your second point is that the article I offered does not meet 'the criteria' for serious scientific research and might be discarded as self-serving marketing hype (which is also Pat's take on similar info). I hope I understand this correctly? By implication one could also conclude that since no scientific proof of jitter audibility has been presented to Pat his position is supported/proven? Hmmm...questionable, that one. (As a side note - did anyone bother to pay the $20 and read the AES article mentioned earlier in the thread which might provide scientific research that supports the audibility of low level jitter? No? Okay then, just checking) In my view, what we're really arguing is competing belief systems. If I understand correctly, you and Pat believe that only 'acceptable scientific research' yields valid answers in the real world. All else is snake oil or self-delusion. Science is the ultimate test of anything. That's fine as long as you realize your reliance on 'scientific proof' is a personal belief system. You believe in the scientific method (or maybe it's infallibility?). Unfortunately, science is remarkably fallible in the real world and even careful research can lead to all sorts of interesting outcomes. Take caffeine for example. Caffeine is bad for you. No wait, new study - caffeine is good for you. Oops, we did another study and it's only good in moderation. Well...which is it? (And was the pro-caffeine study paid for by Folger's Coffee?). Science is just as susceptible to commercial influence as any other human endeavor. To hold scientific research up as the only acceptable standard for right or wrong is...debatable. With the above in mind, I provided an example of an article providing a series of experiments and listening sessions that meet my criteria (belief system) for acceptable methodology. So you are more skeptical than I am and you reject the method and the conclusion. Fine. But that's your choice and you own it. If you choose to reject someone's example because it doesn't match your beliefs that's fine, but don't make it the other person's responsibility to support your beliefs. That's my bone with Pat. He's demanding other people toe the line and conform to his belief in science as the ultimate arbiter of what is valid and what is snake oil. Um...no thank you. It's okay to "believe" that for any test to be valid it must be blind. It may be wrapped in science but it's still a 'belief'. An opinion. Completely valid, but only to the holder of the belief. I think several posters on this thread were trying to make a similar point in their own ways. Everything is relative. There is no right or wrong, just better or worse. No time to argue with someone who's mind is already closed. They simply don't share Pat's belief system and didn't want to be pulled into defending their own. I don't blame them. Perhaps this is why Pat always gets so much pushback when he demands scientific proof? What he's really demanding is that everyone buys into his belief system. Not going to happen. Best regards, Pete -- Pete Fowler ------------------------------------------------------------------------ Pete Fowler's Profile: http://forums.slimdevices.com/member.php?userid=20270 View this thread: http://forums.slimdevices.com/showthread.php?t=56425 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
