How does the “surround-sound” technique work?
Surround Sound which was introduced by Dolby Laboratories Inc to position sound around the audience so that the effects within movies would make them feel as though they were really there. The use of directional sound from different points in the room according to their depth, sharpness and clarity was the main goal. Starting off from a standard called Dolby Stereo, two separate channels were introduced, both left and right, so that other speakers could in turn double-up to provide a multitude of left and right channels all around the audience. The input of a effects channel (later called Surround channel) was implemented so that a sense of ambience and spatiality could be experienced from the audience. This surround channel was positioned behind and to the left and right of the audience provided the sound depth that the audio engineers were looking for.
This then gave way to a standard, which was known as Dolby Surround, soon followed by Dolby Surround – Pro Logic. This standard incorporated the original two channels for sound, but had an in-built decoder so that the surround channel, and also a center channel (positioned to the direct front of the audience) could be played back to enhance this surround feeling. A many number of speakers could be connected up to enhance the feeling associated with the different types of audio sources, and in turn provide more depth and realism to the audio source.
Dolby Digital was incorporated into the home cinema as well as movie theatres to provide the ultimate audio reproductive source. The use of individual speaker components positioned around the audience comprising of a front left, front right, surround left, surround right, center, and subwoofer speaker were given their own audio input. This was called Dolby Digital 5.