1) Biaural 2) Binaural 3) Stereo 4) Two-channel 1) Biaural 2) Binaural 3) Stereo 
A type of audio system that uses two or more speakers or channels to reproduce spatial information, giving the listener the illusion of lateral placement of sounds between two speakers and their relative distance from the listener. (WW)
[adj] - (electronics) designating sound transmission from two sources through two channels
stereophonic Giving the impression of a spatial distribution in reproduced sound; specifically, employing two or more channels of transmission and reproduction so that the sound may seem to reach the listener from any of a range of directions.
stereo adjective designating sound transmission from two sources through two channels
pertaining to a system of sound recording or reproduction using two or more separate channels to produce a more realistic effect by capturing the spatial dimensions of a performance (the location of performers as well as their acoustic surroundings), used esp. with high-fidelity recordings and reproduction systems (opposed to monophonic). Cf.
designating sound transmission from two sources through two channels