1969, irregular hybrid formation from Latin-derived quadri- "four" + phonic, from Greek phonē "sound, voice" (from PIE root *bha- (2) "to speak, tell, say"). The goal was to reproduce front-to-back sound distribution in addition to side-to-side stereo. The later term for the same idea, surround sound, is preferable to this. Quadrasonic (1970) was at least not a hybrid. Related: Quadraphonics; quadraphony.