QUOTE (Arnold B. Krueger @ Nov 20 2013, 15:22) <{POST_SNAPBACK}>
QUOTE (knutinh @ Nov 19 2013, 07:09) <{POST_SNAPBACK}>
I want a testing method that allows me to "scan" through a continuously variable sound-altering mechanism to (economically) search for thresholds of Just Noticable Difference or Unbearable Level of Difference.
There is the rub - setting up a mechanism for continuously varying a sound-altering mechanism.
This is doable for simple things like hearing thresholds - the widely used up/down test depends on having such a mechanism.
Dolby made such a mechanism for jitter, and IME that's not too hard to do. Did anybody say "Deep pockets"? ;-)
But the arbitrary case taxes the mind.
It is far easier to set up a list of target percentages of sound alteration and making files that fit the list.
In my mind, a sensibly chosen range of 100 is practically the same as continous. I.e. if you can create the degradation in MATLAB or something else offline into a sorted set of 100 files, then any testing methology that lets me have good estimates on JND etc on those is interesting. Disk space is cheap. CPU cycles are cheap. My life-span (and attention-span) is finite...
I am more concerned with How do you "train" properly (start out with the most degraded sample?), how do you avoid listening fatigue (minimize the listening time?), and how do you cope with inherent variability of listeners ("backtrack" to some degree?)