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Definition: surround sound

A recording and playback system that provides a realistic audio environment for a home or movie theater. Action movies as well as concerts are greatly enhanced with surround sound techniques.

Channel Based
The first audio reproduction used one microphone and one speaker. Subsequently, more microphones were used but were all mixed into the same monophonic channel. In the late 1950s, stereo players and phonograph records emerged, creating a more pleasing sound experience. Four-channel sound appeared in the 1970s but never became popular (see quadraphonic sound).

Today, the most common surround system is the 5.1 layout, which creates a 2D horizontal plane of speakers around the listener. It comprises left, right and center front channels along with left and right channels toward the rear, plus subwoofer (see home theater speakers).

Object Based
Object-based audio still relies on channels but includes meta-data. For example, the meta-data can add x-y-z coordinates that describe where the sound should be located. The playback system takes into account the speaker layout and "renders" the sound accordingly. However, very often, the required speaker layout is not what the scene creators intended. Other applications of object-based technology are multiple language support and dialogue volume.

Scene Based
Higher Order Ambisonics (HOA) treats the audio environment as a sphere all aimed at the center where the microphone is located. Ambisonics has not yet been endorsed by major studios. See Ambisonics.

A hybrid format combines different technologies. Dolby Atmos and DTS:X are widely known as object formats; however, they use mainly channel-based sound and are thus "hybrid" formats along with MPEG-H and Auro-3D. See Immersive Sound, Dolby Atmos, DTS, MPEG-H, Auro-3D and wave field synthesis.

Outputs to Stereo, 5.1 and 7.1 Systems
This Oppo Blu-ray player has outputs to three surround systems and a maximum of eight amplifier inputs: front left/right (FL/FR), center (C), surround left/right (SL/SR), surround back left/right (SBL/SBR) and subwoofer (SW).