QUADRAPHONIC or QUADRAPHONY
A form of STEREOPHONIC or multi-channel reproduction in which the sound source is spread around the listener by the use of four tracks or CHANNELs in recording or transmission and the use of four (or more) LOUDSPEAKERs. Conventional music or speech may be recorded in this way, in which case the speakers behind the listener add REVERBERATION to the original sound or are simply out of PHASE with respect to the front ones; or new works may be composed in which all tracks carry original material.
Commercially, quadraphonic sound became available about 1970. However, it has been in use in Europe for ELECTRONIC MUSIC since the 1950s. Today, eight-channel or octophonic systems have superseded quadraphonic ones.
Compare: MONOPHONIC, STEREOPHONIC. See also: ACOUSTIC SPACE, DIFFUSION, KUNSTKOPF. Also spelled quadriphonic.