Quadraphonic

прилагательное квадрафонический (о звукозаписи и звуковоспроизведении)

Большой англо-русский словарь

Quadraphonic

also quadriphonic adjective Etymology: irregular from quadri- + -phonic (as in stereophonic) of, relating to, or using four channels for the transmission, recording, or reproduction of sound • quadraphonics or quadriphonics noun plural but singular in construction

Merriam-Webster's Collegiate Dictionary