There are two different types of surround sound; digital & analogue.
Analogue surround sound creates audio from rear channels by artificially extracting the common sounds between the left and right channels and the centre channel finds the differences between them all to give its own output.
Digital surround sound gives more directions from which you can send sound to the listener; each direction requires a separate channel. The common multichannel configurations available in consumer products today are 5.1, 6.1, and 7.1 systems.
There are a few ways to set up surround sound, the simplest uses several speakers around a listener to play audio simultaneously. Another method is to set up the speakers where the wave fronts come together in a central point “sweet spot” in the room and the wave front is subtracted as you move away from the point.
Another way uses WFS (Wave Field Synthesis) which distributes sound waves evenly over a whole area so there is no particular ‘sweet spot’ this used particularly within arenas and music clubs. This is at a far greater cost of using multiple loudspeakers and a computer system that can control them.
For sound engineering purposes lets say an engineer wants to create a 5.1 Mix and distribute it on an audio CD the software will need to split the tracks into 6 output destinations that have been processed by the engineer. Left rear, right rear for example. So you could have the song playing in all the speakers and say have added sound effects in the rear speakers. Much like movies where a car coming from the right of the screen will come from the right speakers and move to the left as the car travels off screen.
A sound card that has either 6 channel analogue out connected to the speakers OR a digital-out soundcard (S/PDIF) these digital soundcards are indicated by their logo below.
A lot of computers nowadays have these types of soundcards for the commercial use of home theatre systems. They are easily obtainable and more and more people go for this advanced way of hearing sound.
Setting it up is quite easy too now on Windows XP, simply by going into the advanced sound properties and selecting 5.1 or whatever. On some P.C’s there is small program where the speakers can be altered so that some may be louder than the other (good for awkward shaped rooms). After this they are all set up and ready for use!
