Surround Sound

Surround sound is the concept of expanding the spatial imaging of audio playback from 1 dimension (mono/Left-Right) to 2D or 3D. This is often performed for a more realistic audio environment, actively implemented in cinema sound systems, technical theatre, home entertainment, video arcades, computer gaming, and a growing number of other applications. Many popular surround sound formats have evolved over the years. They include ambisonics, quadraphonic, Dolby 5.1 Surround sound, and DTS.

Surround sound can be created using several methods. The simplest to understand uses several speakers around the listener to play audio coming from different directions. Another approach involves processing the audio using psychoacoustic sound localization methods to simulate a 3D sound field using headphones. The third approach, wave field synthesis, uses a very large number of speakers to generate the "audio hologram" of the original audio in the whole room (as of 2004 the only commercial implementation of this is Iosono).

Surround sound is not limited to placement of speakers along a flat (2-dimensional) plane. Vertically-located audio sources can be considered.