In case you tire of photocell for sound (ahh but who could?), here’s a demonstration using an entirely different type of sensor -

Short demonstration of the device used for my “Nunk on Droise” (Noise Under the Influence) performances.
The device is constituted of three alcohol sensors connected through an Arduino board to a computer running a Pure Data patch. The bars on the computer’s screen correspond to the content of alcohol detected by each sensor.
Sorry for the sound that is really bad.

They seem quite sensitive – performing at a club/bar with these may prove a bit unruly, possibly quite fun.