Stereophonic sound
Stereophonic sound, or more commonly stereo, is a method of sound reproduction that recreates a multi-directional, 3-dimensional audible perspective. This is usually achieved by using two independent audio channels through a configuration of two loudspeakers (or stereo headphones) in such a way as to create the impression of sound heard from various directions, as in natural hearing. Because the multi-dimensional perspective is the crucial aspect, the term stereophonic also applies to systems with more than two channels or speakers such as quadraphonic and surround sound. Binaural sound systems are also stereophonic. Stereo sound has been in common use since the 1970s in entertainment media such as broadcast radio, recorded music, television, video cameras, cinema, computer audio, and internet. Etymology The word stereophonic derives from the Greek (stereós, "firm, solid") + (phōnḗ, "sound, tone, voice") and it was coined in 1927 by Western Electric, by analogy with the word stereoscopic. Description Stereo sound systems can be divided into two forms: the first is true or natural stereo in which a live sound is captured, with any natural reverberation present, by an array of microphones. The signal is then reproduced over multiple loudspeakers to recreate, as closely as possible, the live sound.