http://www.youtube.com/watch?v=tWta5o7hdmg

The ResoDrum is an electronic instrument played like a hand drum. It is both sensor and speaker.

The sounds you are hearing are coming from the ResoDrum itself, via a transducer bolted to the underside. Tap on it lightly and you get small percussion sounds; hit it hard and it goes berserk.

(Note that the audio and video are slightly out of sync. The ResoDrum reacts without noticeable latency.)

via AlloyElectric