This is a kind of quantised 6 channel theremin instrument I thought you may be interested in:

Info.

This a test rig for an installation I’m planning. It comprises of a Raspberry PI running Raspbian and Pd-Extended. This is connected to an array of 6 proximity sensors via an Arduino with the Firmata firmware.
The Puredata patch allows you to chose or create scales, select tempo, note ranges and transposition. Sound is produced by 6 channels of Karplus Strong string models with delay. The built in RPI sound output is used.
The Raspberry is oveclocked to 1ghz, CPU usage is around 75%

click through to see the vid

http://jnrhacksaw.tumblr.com/post/43488930384/raspberry-pi-with-puredata-arduino-and-sensor