Surround basics

Surround sound is a common name for various techniques for positioning audio in reference to the listener. Whereas regular stereo is limited to left/right positioning, within a relatively narrow field, surround sound opens possibilities of positioning an audio source anywhere around the listener. Surround sound comes in many formats. The differences between the formats are in three areas:

The number of speakers. This varies from 3.2 all the way to 8.1.

The angles of the speakers.

The intended final coding format. This depends on the media the audio will be "stored" on: film, broadcast video or DVD, for example.

The most common format is 5.1, which consists of five full-range channels and a low-frequency effects (LFE) channel (the “.1” in 5.1 is the LFE or sub channel). The five full-range channels are reproduced by left, right, and center speakers positioned in front of the listener (L, R, and C for short), and left and right surround speakers positioned behind the listener (Ls and Rs for short). The LFE channel can be routed to the main speakers or to a subwoofer that can be positioned almost anywhere.

The center channel is typically used to lock dialog box or sounds to a video screen. The LFE channel is generally routed to a subwoofer to enhance low audio frequencies for effects such as explosions or crashes. Audio in this channel is limited to a range of approximately 25 Hz to 120 Hz.

 

See:

Configuring SONAR for surround mixing