Léon Theremin built his eponymous instrument in 1920 under Soviet sponsorship to study proximity sensors. He later applied the idea of generating sounds using the human body’s capacitance to other physical forms like the theremin cello and the theremin keyboard. One of these was the terpsitone, which is kind of like a full-body theremin. It was built about twelve years after the theremin and named after Terpsichore, one of the nine muses of dance and chorus from Greek mythology.
Instead of waving one’s hands near loops or rods, the terpsitone was played by dancing atop a large steel plate. As the dancer bends down toward the plate, capacitance increases and the resulting pitch decreases. Raising up away from the plate has the opposite effect; capacitance plummets and the pitch increases. As with a theremin, the oscillator being controlled by the dancer beats against a fixed oscillator. The output is amplified and sent to a loudspeaker.
A built-in light show set the terpsitone apart from the other theremin-esque instruments. For each pitch sounded by the dancer’s movements, a corresponding colored glass lamp would illuminate. Each light was driven by a reed that vibrated sympathetically with a certain pitch, closing the switch and lighting the lamp.
The terpsitone was even more difficult to control than the theremin. In the short video after the break, the player makes do by crouching on the plate and controlling the pitch with his arm and fingers. Unfortunately, only three terpsitones were ever built. The last one was built in 1978-79 for acclaimed theremin player Lydia Kavina, who happens to be Léon Theremin’s grandniece. This is the only surviving instrument, although the spirit of gesture-controlled musical composition lives on in wearable instruments and console games like Wii Music.
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