Naphtali:
As to testing, as far as I know, there has been one at least semi-scientific test of quieting bow noise. Is wasn't where arrows were shot in the presence of deer or elk, but a test with sound monitors in frequencies for both human and animal ranges. The latter is important as what we think may be quiet, what deer think may be two different things. All other tests that I have read or heard about, are just a one or a couple of guys standing around comparing bows.
BTW, even Asbell in the newest Traditional Bowhunter shows using a high tech sound meter in an attached pic.
Denny Sturgis has an article about quieting bows in the mag as well.
I have a couple sets of Bowhush on order right now, as I don't know if what I'm using right now is the final answer. I have used beaver fur, mink fur, several types of wool, bow jacks, cat whiskers, etc. In a recurve it is important to cushion the string grooves as well.
waterone