The Cave of Sounds, interactive sound installation

The Cave of Sounds is eight newly-conceived digital musical instruments arranged in a circle. You walk up to one, intuit what to do (there are clues!) and make some noise.

A central program receives performance data from each instrument (tempo, pitch etc) and sends partial control data back to help the instruments converge musically. It also tries to detect when people are playing together and project some graphics on the floor in the centre of the circle to show the connections being made (actually the graphics haven’t been working so far but they will be present in the next show, see below!).

There are eight of us (all visitors of the London Music Hackspace) working on this project, making one instrument each, and everyone’s gone about it differently so there’s a whole bunch of frameworks, software and hardware in effect - my particular instrument is built with openFrameworks though. It’s a flat surface with a lamp shining down on it, you put your hands in between and cast shadows in the shape of animals for the computer to respond with accordingly animal-esque sounds.

Here’s a shot of the GUI (not visible to the player):

There’s a (ordinary 2D) webcam under the thin surface watching the shadows from the other side, and then OpenCV helps to find the edges, determine where the fingers are pointing, whether a dog’s ‘mouth’ is opening or a bird’s wings are flapping and so on, and then those parameters go to the sound engine which plays cut-up dog and wolf samples or does some amplitude/frequency modulation to approximate birdsong.

Thanks especially to Kyle McDonald for his ofxCv. Although I didn’t use it directly in the end, looking at his code got me on the right track.

We’ve been fortunate to show the installation at the Barbican and the V&A in the past couple of months and there’s one more show coming up in London on 1st-3rd November at the Watermans arts centre, so if you’re in town come take a looksee :). Details at our website: