When I think of "rattlesnake sound", I think of those little plastic boxes of TicTac breath mints, half full, shaken as short and fast as you can.

Another "synonym" for that rattlesnake sound that I conjure up is one of those old party favor noisemaker toys. I don't know what they're called, but it's like a pencil-stick you hold upright in your hand and you swing the top around with centrifugal force, sort of like a hula-hoop motion, but with your hand. It makes a buzzing-type sound.

Funny how many of us associate the rattlesnake's sound with some other more common everyday sound. And the sounds we choose to describe with are all so different. Probably each snake has its own semi-distinctive variation of the sound, and we're all remembering the one that made the biggest impression on us!