Surround sound is an effective way to enrich the way that sound is delivered, by creating the impression of being 'immersed' in a 3D sound environment, surrounded by whatever you're listening to. It uses a range of techniques to achieve this through the use of additional, discrete speakers and subwoofers.
Home cinema or music?
In most cases, surround sound is used for home cinema or computer games. While some audio formats do support 5.1 or even 7.1 channel surround sound, in most cases the audio was recorded specifically to be played back on stereo speakers. The sound for modern movies, by contrast, is normally engineered to be best appreciated on a surround sound system.
5.1 and 7.1 channel surround sound
The different specifications of surround sound, 5.1 and 7.1, basically refer to the number of speakers/subwoofers in a room. For example, 5.1 surround sound consists of five speakers and one subwoofer (two speakers and one subwoofer at the front, one in the centre and two behind you), 7.2 surround sound consists of seven speakers and two subwoofers, and so forth.
A 5.1 surround system consists of five speakers and a subwoofer - there are three front speakers (one each on the left, right and in the centre) and two rear speakers, which should be either situated behind you or aligned with each of your ears.
A 7.1 channel system is very similar, however instead you have speakers both alongside you and behind you, to give you a more detailed listening experience.
What affects surround sound performance?
The things that affect the way a surround sound system performs are varied, and because surround sound relies on a kind of 'balance' between the different channels, it's not always easy to get it set up just right. Below are some of the things that affect the overall surround experience:
Distance - the distances between where you're sitting and where the speakers are located will affect how they sound. If you're too near or far from your rear speakers, for example, they won't have the desired effect, and the 'scale' of the sound field will be affected.
Positioning - in much the same way that distance makes a difference, positioning your speakers too high or low will affect how things sound.
Direction - if your speakers aren't facing the right way, they're likely to sound muffled and unclear.
