The theremin is an electronic musical instrument. It was invented in 1919 by a Russian physicist Leon Theremin. Besides its unusual appearance, the theremin is also unique in that it is played without being touched.
How does the theremin work?
The theremin typically consists of a box with two metal antennas which create an electromagnetic field. The musician stands in front of the instrument and moves his hands in the proximity of the two antennas, which forms a capacitor between his hands and the antennas. The capacitance of the electromagnetic field varies by the distance between the player and the instrument. The upright antenna controls the pitch. When the right hand approaches the antenna, the pitch gets higher. When the hand moves away from it, the pitch gets lower again. Small, rapid movements of the right hand can create vibrato. The loop antenna controls the volume. Approaching the antenna makes the volume softer. So, the left hand is responsible for dynamics and articulation. The electric signals from the theremin are amplified and sent to a speaker system.
Besides being used in movies to create eerie sound effects, the theremin found it's home in concert music, especially avant-garde and 20th- and 21st-century new music. Several composers created dedicated works specifically designed for the theremin. Among them are Bohuslav Martinu, Joseph Schillinger, Moritz Eggert, Percy Grainger, Anis Fuleihan, Fazil Say, Andrew Norman, Christopher Tarnow, Kalevi Aho and Régis Campo.