theremin

Early electronic musical instrument invented by Leon Theremin in 1922. It is played by the player's hand moving in a magnetic field around a metal loop and rod. It uses beat frequency generation between two high frequency oscillators, one signal of which is fixed, while the other depends on the position of the player's hand in the vicinity of an aerial. Its monophonic sound is voicelike in the soprano register, and trombonelike at a lower pitch. Since the player makes no contact with the instrument, it is difficult to obtain a steady pitch, hence the instrument's wavering quality. Because any position of the hand generates a pitch, the theremin is incapable of detaching notes, so that all intervals are linked together by a wailing portamento, like that of a siren.

Theremin subsequently invented another instrument shaped like a cello on which notes could be produced detached from each other by means of a cello fingerboard.

Edgard Varèse incorporated two theremins in Ecuatorial (1932–33); it has also featured in film scores such as Bernard Herrmann's music for the science fiction film The Day the Earth Stood Still (1951). A transistorized theremin is heard in the Beach Boys' hit ‘Good Vibrations’ (1966).