The Theremin, an electronic musical instrument that you play by not touching it, celebrates the 100th anniversary of its invention next year. Smithsonian looks at the history of the first successful electronic musical instrument that New York Times critic Harold C. Schonberg described as sounding like "(a) cello lost in a dense fog, crying because it does not know how to get home." From Smithsonian:
Theremin was a radio engineer with the Soviet military in 1918 when, while building a powerful transmitter-receiver, he noticed odd feedback sounds coming from it. He said in a 1995 interview, "it turned out that when the capacity changes at a distance of the moving hand, the pitch of the sound also changes."
He had happened on heterodyning, a process that combines two frequencies to shift one frequency range into another, new frequency. It makes for a change in pitch and volume.
Other radio engineers in Europe at the close of World War I had noticed the same effect but Theremin was the first to play with that feedback or heterodyning effect in a musical way. The new sound pleased the inventor. Fully committed to Soviet nationalism, (Metropolitan Museum of Art musical instrument curator Jayson) Dobney says, Theremin "tried to find a musical sound that was modern, forward looking."