So I was watching this video:
And in addition to being mind-blown. I was inspired to make something similar.
Theres 2 vids, and it shows some different sounds in the 2nd one (high frequency resonance).
From what I can understand in the description and wikipedia page (http://en.wikipedia.org/wiki/Feed-Drum) for it, it looks like some kind of sensor/actuator is doing all the work.
It says the head is "electronically conditions" and that the signal is feed back to it via "acoustic pressure". It looks like maybe some kind of pressure sensor? But I've not seen any so thin/intricate/durable (he's whacking the hell out of that drum!). As far as the feedback part, I'm confused there too. There is no bottom head on the drum, and the drum is massive, so that kind of rules out a big speaker inside of it, or something simple like that.
Does anyone have any idea what's going on there?