Machine that electronically generates and modifies sounds, frequently with the use of a digital computer, for use in the composition of electronic music and in live performance. The synthesizer generates wave forms and then subjects them to alteration in intensity, duration, frequency, and timbre. It may use subtractive synthesis (removing unwanted components from a signal containing a fundamental and all related overtones), additive synthesis (building tones from signals for pure sine-wave tones), or other techniques, most importantly whole-sound sampling (digital recording of sounds, usually from acoustic instruments). The first synthesizer was developed c. 1955 by RCA. Compact, commercially viable synthesizers, generally with pianolike keyboards, were produced in the 1960s by Robert Moog (born 1934), Donald Buchla (born 1937), and others. With transistor technology, these soon became portable and cheap enough for practical performance use, and such instruments became fixtures in rock bands, often displacing electric pianos and organs. See also MIDI.