theremin

theremin thĕrˈəmən [key], one of the earliest electronic musical instruments, invented (1920) in the Soviet Union and named for its creator, Leon Theremin. A forerunner of the synthesizer, it consists of a wooden box fitted with two radio-frequency oscillators and two metal antennas, a vertical rod on the instrument's right and a horizontal ring on its left. The player moves the hands in the air around the antennas without touching them, creating changes the antennas' electromagnetic fields. The right hand controls the pitch, the left hand, the volume. The sine-wave tones that are produced are then amplified and fed into a loudspeaker.

The theremin's sound has been described as like that of a violin but more spooky and otherworldly. While some classical composers have written for the instrument, e.g., Henry Cowell and Edgard Varèse, it has been used more frequently in film soundtracks—where its eerie, swooping tones can create an atmosphere of unease or strangeness—and by such rock groups as The Beach Boys, Led Zeppelin, and Radiohead.