http://www.cymascope.com/soundsfun.html http://www.cymascope.com/soundsfun.html Take a look at the second video. It seems that they're using something like the

http://www.cymascope.com/soundsfun.html http://www.cymascope.com/soundsfun.html Take a look at the second video. It seems that they're using something like the resonance plate here: http://www.youtube.com/watch?v=Qf0t4qIVWF4 http://www.youtube.com/watch?v=Qf0t4qIVWF4 (Wikipedia suggests they're named Chladni plates? I've seen them before in a physics class, but I don't know if that's really their proper name or not. See http://en.wikipedia.org/wiki/Ernst_Chladni http://en.wikipedia.org/wiki/Ernst_Chladni ) Edit: I didn't notice it before, but they actually demonstrate the same sort of device further down on the page, also calling it a 'Chladni plate'