http://www.break.com/index/tesla-electric-current-plays-music.html

 

is this really some part of the tesla coil doing it, or is it more likely just set in time to some music?

it gets turned on and off at the frequency of the note they want it to produce. there is usually a chip on the coil that does it. and some people have even hooked instruments up to it so you can use if as a geeky amp

I prefer this one:

 

meh... it sounds better, but i think the first one looks cooler.

i've read about a solid state tesla coil, the guy who built it linked the driver circuit to an audio amp. the arc behaved like a rudimentary plasma tweeter.