The sympathetic resonance/frequency issue isn't only with snare buzz- I was once in a recording studio where my 12" tom would sustain nearly incessantly, as if it was synthesized somehow. When I played single notes down the toms- that all had the same batter & reso heads of the same age and wear- it would go "dooooom, dooooooooooooooooooooooooooooooooooooooooooooooooo (checks watch) ooooooooooooooooooooooooo (finally I stopped it manualy), doooooom. It was weird. That room just loved that specific frequency- the volume was VERY slowly decreasing, so no telling how much longer it would go or if changing the kit's position in the room would change it. I wanted to test it but studio time & dollars were a-tickin'. I slapped a moongel on it to make it match the 10" and 14". Without changing the tuning at all, at the next gig it didn't occur, and never did again for the life of those heads, nor since.