Surround sound
Surround sound formats vary in reproduction and recording methods, along with the number and positioning of additional channels. The most common surround sound specification, the ITU's 5.1 standard, calls for 6 speakers: Center (C), in front of the listener; Left (L) and Right (R), at angles of 60°; Left Surround (LS) and Right Surround (RS) at angles of 100–120°; and a subwoofer, whose position is not critical.