Last weekend I did an installation as part of Cleveland's Ingenuity Festival, which took place (mostly) under the Detroit-Superior Bridge. My piece (Wave Space) used a PD patch consisting of 32 oscillators, independently tunable in ratios related to a common base frequency and a common denominator.

I was given an enclosed space about the size of a small public restroom--the space probably was a restroom for Cleveland's subway, which used to run under the bridge until it was shut down in the 1950s. I brought in a couple of small powered speakers and did frequency sweeps to find the resonant frequencies in the room. It was interesting: with most of them, once the room started vibrating, it was difficult to trace the origin of the tones, even listening closely to the speakers.

In practice, I used 16 resonant frequencies, and paired them with other oscillators with very close values, so they'd modulate--generally for tremolo or slow fades in and out. Over the course of an hour, I faded these oscillator pairs into and out of the system, and also adjusted modulator values. Then I left the system in place to play the recording for the duration of the festival. You can hear it (free streaming, free download) here: http://snwv.bandcamp.com/

-Maurice