Anything quadraphonic involves four-channel audio — music or other sounds that are transmitted from four separate directions. Quadraphonic sound is obsolete today.
Quadraphonic records and sound systems were briefly popular in the 1970s, and many musicians recorded albums especially for the four-channel system. Similar to some versions of "surround sound" today, quadraphonic sound involved four speakers arranged around the listening area, and music that was split into four different sections, or channels. It eventually failed because it was expensive and had various technical problems. Quadraphonic comes from the Latin quadri-, "four," and the Greek phone, "sound."