This dispute goes on in audio circles, too. Does the sound of a speaker change over time? Undoubtedly it does, because it is made from very soft materials driven by electrical current to move back and forth from 40 times per second up to 20,000 times per second (in theory). Wear and tear takes its toll.
How long does it take repeated strikes to change the molecular structure of a cymbal? Nobody knows. One thing that is known, though, is that human "auditory memory" is only a few seconds long. (Not to be confused with the auditory memory that allows us to recognize - not remember - voices, etc.) Our ears, however, adjust themselves to audio input to allow us to hear more of what we want to hear over repeated exposure. IE, we learn to "tune out" audio qualities that we find objectionable. Just don't tell your wife!
(I thought that I had this study bookmarked, but I can't find it. It was on one of the stereo forums.)
GeeDeeEmm