Surround sound simply means having one or more speakers with discrete audio signals (channels) placed behind the listener in addition to the typical stereo pair.
There are multiple types of surround formats in use (from three-channel LCR to 7.1, which has eight channels).
The most common surround format is 5.1, which refers to having 5 speakers and a sub-woofer (the “.1”). 5.1 is used in movie theaters and home entertainment systems. Additionally, most DVDs are mixed to 5.1. The standard speaker placement for 5.1 for surround monitoring is stereo left and right speakers, and an additional center speaker in front, two more stereo left and right speakers in the rear, and the sub-woofer on the side.
Pro Tools HD and Pro Tools with Complete Production Toolkit support mixing in surround formats. In Pro Tools, each surround format is considered to be a
greater-than-stereo multichannel format.