This guy also posted ABX results on Head-fi thread _*jitter_&_audibility (\"http://www.head-fi.org/t/668878/jitter-correlation-to-audibility/105#post_9824683\";)*_ again giving his detailed description of his listening technique
As per the Gearslutz thread, it shows that the first step is identifying & isolating a specific aspect or artifact in the music that can be focussed on during blind testing. Without this step there is absolutely no point in going any further as I advised JH901 It also shows that this is likely to change based on the track being used for testing. Detailed descriptions of the listening technique & experiences of those who complete a successful ABX test are educational & should be more widespread as it should help anybody who wants to seriously engage in an ABX test Here are his comments after each ABX test done on a new file produced to him: > Not much to listen for here, especially in such a busy and trebly mix. > Too sizzling for my taste, I'd want a do-over if a recording studio > handed this to me as a client.If you want to give it a shot, here's how > I got to it: find the shortest, sharpest, loudest transient you can. No > cymbals, the 'short' is important. I used the second-to-last snare hit > in the clip. Use the 'A' version to burn that sound into your mental > ear, then compare directly to X and to Y, either one first. To my ears, > the jittered version was just slightly blurred. > > Nick, if y'all want to pursue this, I'd be thinking about something that > might expose graininess and breakup due to jitter on sustained notes, > instead of hunting down transients. Classical piano, slow, with a held > chord somewhere? I don't have any software to deliberately jitter with, > so I'd need to pick that up somewhere. > Well, I will insist on the caveat that *all* ABX testing is of a sort > pretty much wholly removed from how one would normally listen to music. > The protocol can't be completed otherwise. The *only* time I ever > listened like that in real life was when I was trying to hear John > Lennon say "I bury Paul" at the end of "Strawberry Fields". [image: > http://files.head-fi.org/images/smilies/biggrin.gif] That said, > Yes, my first research question is usually "Is differentiation possible > at all???", and so I use the tools available to hunt for the > differences. > It was particularly difficult in this case, as I don't have a good sense > of what problematic jitter *ought* to sound like, and it matters what > testers are listening for. > > Since I can pick out a difference on one snare hit, a further refinement > would be to listen more 'casually', and see if the drum set sounds > different throughout. > > I'm guessing that the added jitter track would have been > indistinguishable for this particular music, but it's faintly > conceivable that interested listeners could learn to hear the difference > without the procedures I described. > Of course, this time I had the enormous benefit of knowing what to > listen for (snare), that I could apply across the track. No hunting > around for artifacts. > I hear the jittered drum set as *slightly* less precise. The jittered > version thuds instead of snapping tightly. It's a *tiny* difference, but > you can find it anyplace that the cymbal-crazy drummer isn't covering it > up. If I had to reverse-engineer from the treatment, I would hypothesize > that the applied jittering is smearing/obscuring the attacks slightly. > This is two tests of the same two files, pathn versus pathj, so there's > replication of the result. > I did previous tests listening for any kind of noise or breakup effect > on the sustained chords. Those are all null, failure to positively ABX. > So if there's some sort of calculable noise contribution of the jitter > to the signal, it was inaudible to me. > > Short sharp snare hits are not available in this track, so I had to > re-learn how to detect a difference. > > Since the Range sample cued successfully on the snare hits, I switched > to listening to the piano note attacks, and that provided the successful > cues. The non-jittered piano was just a little more delicate and > focused, while the jittered version had just a little more thump and > spread in it. Soft chords, listened to at soft levels, worked best to > detect this difference. > Are we highly confident that there is no other possible source of > differences in these tracks? > The tests below are for path30n versus path30jl. > I have learned what these clips sound like, and I am learning (maybe) > what jitter sounds like. > But even discounting for some sort of learning factor, path30jl was > ABXed with precisely the same characteristics as path30j (soft piano > attack), and with less difficulty. > Cue again was focus and delicacy (better focus in n). > As you can see, both tests took close to three minutes, and were > conducted minutes apart. > ............ > If the level of distortion is scaling linearly to the severity of jitter > applied, it is not apparent. I expected less difference, but that was > not my experience. > > Replications, anyone, please? Pick any soft chord attack, pick the more > delicate, more focused one. I might also describe the 'n' as more > 'realistic'; the jittered version seems slightly off-balance EQ wise, > like a virtual piano instead of a real one. > Like all the tests, this ABX requires replication, including multiple > testers, before there's any point drawing conclusions about it. Getting > into a pretty subtle area here. The earlier files seemed to be close > together in terms of the audible effect of jitter, but path30jr is more > challenging. Still using the same cue, quality of the piano attack in > soft passages, but there's less of it here. > Yes, these are normal listening levels, it interferes with > identification if I crank levels. The cue is the moment of attack, as > the hammers strike the strings on quiet chord. The loud chord at the > beginning is too complex, at least with what I'm able to do so far. I'm > still cuing on "focus", which is a poorly defined descriptor. The > jittered chord also sounds different in a way I might call frequency > balance--it becomes *slightly* less realistic than the 'n' version, out > of balance in its frequency spectra as I'm listening for the full round > piano tone. > Earlier I was listening for quiet chords near the end. These last two > reports, I used quiet chords before the big sound at ~21 secs. > Hate to muddy the waters, and I appreciate all the responses above, but > this report here was generated on the "'cheap' > (http://www.amazon.com/dp/B003EM8008/)" earphones with motherboard > chipset DAC. > > I have to think it's not about fidelity of the equipment, it's figuring > out what to listen for. Listening for jitter is *unlike* other ABX > comparisons I've done before. If it helps, I try to imagine the sharpest > focus of sound in terms of how "narrow" I can hear the piano attack, as > though it were a spatial measure. The narrower attack is 'n'. It is > difficult because I'm continually tempted to chase mirages of > differences in other details. If I stick to "focus" and "narrow" I get a > result. > Replication. This is just path30jr versus path30n again, to establish > the reliability and consistency over more rounds.Back to the > Beyerdynamic 770 Pros for these. I'm listening in the mids, if that > helps any. The notes are "shaped" differently not in the bass extension > or treble extension, but in the core of the piano attack, where it seems > that the 'n' is focused, while the jr has a slightly 'flattened out' > aspect. This was listening for the quiet chords right near the end > again. > > Since the "noise" component was mentioned above, I'll mention that I'm > not listening for noise, since that gives a null result--no discernible > difference I can detect on that basis. ------------------------------------------------------------------------ jkeny's Profile: http://forums.slimdevices.com/member.php?userid=35192 View this thread: http://forums.slimdevices.com/showthread.php?t=96407 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
