Surround Sound Basics

In a 5.1 surround sound system there are six speakers:

1. 3 in front of you: front left, centre, and front right,
2. 2 behind you: rear left and rear right,
3. plus a sub woofer that can be placed anywhere (humans can’t detect direction of low frequencies).

Each of the 5 speakers is precisely placed around you to create a 3D sound field that makes you feel like you are immersed in a situation. In a properly setup sound room you should be able to accurately determine the direction that any sound originated from, but you need to be in the sweet spot – that small location in the room where all the 5 speakers are the same distance from you and perfectly tuned.

How We Detect Sound Direction

Psychoacoustic research has established that to detect the direction of a given sound we need to have 3 pieces of information of that sound,

1. the timing difference between each ear
2. the volume difference between each ear
3. the frequency modifications from it reflecting off each ear (pinna effect)