its definately awesome that he is not making noise with a speaker but lightning. That rocks pretty hard. It would be really cool if it didn't sound like a pissed off bumble be though. Nikola Tesla is absolutely fascinating btw.
Plasma speakers are a different way of using odd 'speakers' (in this case, plasmas with varying intensity instead of paper and plastic cones glued to fuckoff-big magnets) to make sounds, and they seem to be fairly effective and hi-fi.