The use of multiple loudspeakers placed around the listening position with the aim of reproducing a sense of envelopment within a soundstage. Numerous surround formats exist, but the most common currently is the 5.1 configuration in which three loudspeakers are placed in front of the listener (at ±30 degrees and straight ahead), with two behind (at ±120 degrees or thereabouts), supplemented with a separate subwoofer.