Surround is an acoustic reproduction technique used to simulate surround sound. It is a multichannel or multi- channel reproduction in which the area to the side and behind and - in certain processes also above - the listeners is also reproduced by loudspeakers. The lateral and rear signals, in conjunction with additional loudspeakers, convey an enhanced surround sound.
Surround configurations can consist of the front speakers, the left and right center speakers, the center speaker, the side and rear speakers, and the woofers. The configuration is specified in the nomenclature: speaker boxes.Bass reflex speakers. Thus, a 5.1 configuration says that the surround system has five speaker boxes and an LFE channel for a subwoofer, arranged as follows: Center, center left and right, rear left and right, and a bass reflex box.
Surround technology is used in cinemas and home theaters. The available methods are Dolby Digital, Dolby Surround, Digital Theatre Sound( DTS), Sony Dynamic Digital Sound( SDDS), Tomlinson Holman Experiment( THX) and MPEG Surround.