Synthesizers were first used in pop music in the 1960s.
In the late 1970s, synths were used in progressive rock, pop and disco.
Most of these early instruments used heterodyne circuits to produce audio frequencies, and were limited in their synthesis capabilities.
The ondes martenot and trautonium were continuously developed for several decades, finally developing qualities similar to later synthesizers.
Gray also built a simple loudspeaker device into later models, consisting of a vibrating diaphragm in a magnetic field, to make the oscillator audible.
This instrument was a remote electromechanical musical instrument that used telegraphy and electric buzzers that generated fixed timbre sound.
Thaddeus Cahill's 1897 patent for his electromechanical instrument, the Telharmonium, uses the verb synthesize 25 times, for example in the phrase "synthesizing composite electrical vibrations out of the ground-tone vibrations and the overtone vibrations" (a description of additive synthesis).
Prominent composers including Vladimir Ussachevsky, Otto Luening, Milton Babbitt, Halim El-Dabh, Bülent Arel, Charles Wuorinen, and Mario Davidovsky used the RCA Synthesizer extensively in various compositions.
He accidentally discovered the sound generation from a self-vibrating electromechanical circuit, and invented a basic single-note oscillator.
This instrument used steel reeds with oscillations created by electromagnets transmitted over a telegraph line.