Pun intended, of course. You're welcome.
And as pointed out above by nick_charles, there are plenty of successful DBT trials for certain things: this ranges from slight FR tweaks, artificially created (relatively very high in magnitude) jitter, noise levels, harmonic distortion levels, etc. Note that some studies like Meyer and Moran also include some supplemental results of conditions where differences were heard and so on. There may be some meaningful context for a null result, even if it's not one that you are expecting or that you don't want to see.
Anyhow, the better studies are ones where a threshold is established. e.g. how many cheap op amp buffers in series can be strung together before there's audible degradation (which was done)? A null result in a vacuum could just be an insensitive testing procedure, but they're not all like that. Yes, it could be that a listener or whatever else isn't sensitive enough, and a threshold that's too high gets established by a study. That's why some audibility thresholds tend to be based on multiple studies if possible and generally quoted pessimistically to give some margin for error. w.r.t. jitter, nick_charles has covered it very well
Edited by mikeaj - 8/4/13 at 11:39am