I created this project in conjunction with The Gizmo Dojo (the Broomfield, CO maker space). The idea is pretty simple – using ultrasonic sensors as input and translating distance measurements into MIDI notes that are then played via a software synthesizer on the Raspberry Pi. I have written up a detailed instructable on how to build this.
Here’s a video showing an early prototype playing a single instrument (piano).
This video shows a modified version where each sensor causes a different musical instrument to be played.
Finally, here is a full demonstration of the finished product, demonstrating the gesture controls.