Pasapas

In 1981, composer Rolf Gehlhaar presented Step by Step – Music for Ears in Motion in the Espace de Projection at IRCAM in Paris. The installation consisted of sixteen loudspeakers suspended in a twelve-meter diameter circle. A software program written by Philippe Prevot generated a sine wave signal and distributed it among the sixteen speakers by projecting one cycle to each speaker in turn. After one speaker played a cycle of the sine wave, the next speaker would play the next cycle. A listener located at the exact center of the circle would hear the sine wave reconstructed at its original frequency. A listener at any other location would experience a changed timbre because of the different amounts of time the sounds took to reach the listener, and because of the resultant breakup of the original sine wave.

Gehlhaar had been thinking about location dependent sound since his experience directing daily performances of the Stockhausen Ensemble in the German Pavilion at EXPO ‘70 in Osaka. He wrote, “for some years I asked myself whether it would be possible to find a method of creating a sound which would actually change in pitch according to the position and movement of the listener in the acoustical space.” The consequence of the constructive and destructive interference in Step by Step is that certain components of the spectrum of each pulse are either reinforced or suppressed depending on the specific position in the acoustic space. Each listener has a unique spatial-temporal perspective. By virtue of their position or direction of movement, the listener creates their own unique sequence of sounds.

I recreated Step by Step using eight speakers arranged in a circle. Experimenting with different frequencies, I found that frequencies in the 200 Hz range produced the most interesting results. Standing in the center, the original 200 Hz tone was clearly heard. Moving to any other location, a distinctive sound emerged that changed when I was in motion and became static when I was still. The sound was dependent on the act of moving my ears. I also experimented with adding multiple sine wave pulses at different frequencies and discovered that more complex textures could be produced with harmonically or inharmonically related partials.

Pasapas extended this work to sixty-four speakers arranged in a hanging octagon, divided into eight groups of eight.

Exhibitions

AiR Residency Program, 8th Street Marketplace, Boise, Idaho, February 2010