Theremin by Masami Takeuchi

(Theremin on Wikipedia)

The theremin or thereminvox (originally pronounced [teremiːn] but often anglicized as [ˈθɛɹəmɪn] [1]) is one of the earliest fully electronic musical instruments. It was invented by Russian Léon Theremin in 1919, and it is unique in that it was the first musical instrument designed to be played without being touched. It consists of two radio frequency oscillators and two metal loop antennas. The electric signals from the theremin are amplified and sent to a loudspeaker.

To play the theremin, the theremin player moves his or her hands around the two metal antennae, which control the instrument's frequency (pitch) and amplitude (volume). The theremin is widely associated with "alien", surreal, and eerie-sounding portamento, glissando, tremolo, and vibrato sounds, due to its use in film soundtracks such as Spellbound, The Lost Weekend, and The Day the Earth Stood Still. The theremin is also used in art music (especially avant-garde and 20th-century "new music") and in popular music genres such as rock and pop.

Similar electronic instruments, such as the Ondes-Martenot also use the principle of two heterodyning oscillators, but the Ondes-Martenot is touched while it is played.