Sorry this discussion has drifed off-topic from DSP a bit ... please let
me know if this is irritating anyone and I will drop/move this thread.

>> you might have better luck with headphones than speakers.

Agreed. I'll pick up a set of high-end headphones tomorrow to continue my
experiments.

> One is that you may want to try masking with something broadband, but with
a
> little more structure than pure white noise. Something like filtered
> waterfall or engine noise as long as its tolerable.

I'll try that by digitizing some other sounds, then filtering. I bought a
"sound spa" environmental sound machine yesterday as well, but none of the
sample sounds seem to mask well either. "Babbling brook" comes closest.

> You might be fighting a losing battle by trying to increase the
> sound level. The course adjustment might just offset the increased sound
so
> that it is the same relative to the ringing no matter what level of sound

That seems to be the case so far. I had the masking playing loud as heck
through my little headphones, but the tones ride right on top of them. I am
traveling to Portland next week to meet with a bunch of audiology experts on
this thing and will see what they suggest as well. I'll report back here if
I find any kool digital audio gadgets they make for this sort of thing.

Thanks John! Jim