As part of my Creative Music Technology degree at Bath Spa, I’ve created an instrument for our 13-strong ensemble – “Behaviour”.

The core of my instrument is a photocell, connected to an audio mixer’s microphone input. When light strikes the photocell, it generates a small current, which is amplified by the mixer and output to my laptop. In the same way that a microphone translates sound – vibrating air, into a varying current, flashing lights are translated by the photocell into a varying current, which can then be amplified and played through loudspeakers, enabling us to listen to the sound of lights. My instrument uses two flashing cycling lights, a single battery-powered LED, and a large variable-colour stage lamp to excite the photocell. I have modified the stage lamp, replacing its microphone with an input for a magnetic coil pickup, allowing me to trigger the lamp’s sound-activated mode by moving the pickup through magnetic fields, such as around transformers. I process and refine the audio on my laptop, with an equaliser, two pitch-shifters and reverb, all controlled using a simple USB controller.

 

The performance strategy I employ with this instrument is to confine myself to one of five sonic palettes which I have discovered and explored in the development of my instrument. Within one of these palettes I modulate a handful of parameters, which allow me to vary my sonic output, whilst keeping control of the instrument and staying within my chosen sound area. I find this strategy to be very effective for contributing an appropriate palette and creating a diverse spectrum of sound on demand.

 

Though photocells have been widely used in music production since the advent of the Teletronix LA-2A optical compressor in 1965, their use has always been functional. The idea of using a photocell as a “light microphone” comes from the same school of thought as using a loudspeaker as a microphone, as Geoff Emerick, the studio engineer for The Beatles’ album Revolver chose to do for the bass track of Paperback Writer. This creative misuse and abuse of technology is behind many effects we can recognise today, such as the vocoder, originally invented at Bell Labs for wartime communications in 1943 has since been used for the “robot voice” effect that can be heard in many pieces of music. Auto-tune, now widely used and recognised, was originally created for interpreting seismic data in drilling for oil. The inspiration for my instrument came from a video by Eric Archer, in which he uses a photocell to listen to various lights on a drive through Brooklyn. The diversity of the hidden sound-world fascinates me, and I try to emulate it in my work.

We are performing at Spike Island in Bristol, on May 31st, details available here.

Light To Sound from ilumos on Vimeo.

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Filed under: Audio, ableton live, behaviour, instrument