Working with the artist Kathy Hinde, I have been developing the software for the bat box element of her project Vocal Migration. The bat-box is a stand-alone vocal sampler run on a raspberry pi, using a ultra-sonic sensor to modulate the sample. If you want to find out more about the project check here.
The box is made up of a raspberry pi, run from a battery with a arduino board giving controls from knobs and buttons, and also modulating the sound output from a ultra-sonic sensor. Sound in is provided by a sound card, and a powered vocal mic and sound out is via a small powers speaker.