The synthesizer has become hugely influential since the 1960s, but it had many antecedents in twentieth-century electronic instruments. The theremin, invented in 1920 by the Russian Lev Theremin, consists of a box containing thermionic valves producing ethereal oscillations which were modified by moving a hand around an attached antenna.

The ondes martenot was first demonstrated in 1928 by the French inventor Maurice Martenot. It produced oscillating frequencies in a similar way to the theremin. Messiaen used its disembodied sounds in his Trois petites liturgies de la présence divine (‘Three Small Liturgies of the Divine Presence’, 1944).

The trautonium was introduced by the German Friedrich Trautwein in 1930, assisted by Oskar Sala who became the instrument’s virtuoso. Tones were produced by touching a fingerboard, altering the pitch of the oscillation, which was then amplified through a loudspeaker. Hindemith was inspired to write a Concertino for Trautonium and Strings (1931).

The electric organ emerged in the early twentieth century, originally designed as a compact substitute for the larger pipe organ. The best-known of its type is the Hammond organ, patented by its American inventor Laurens Hammond in 1934. It can be heard in Stockhausen’s Momente (1965) and Tavener’s The Whale (1966).