Razer's Surround - virtual 7.1 surround software

Science.

It doesn't actually make a stereo headset into a surround one. I've tried it with a 7.1 headset and a cheap stereo one. If you have bad drivers for your surround sound headset you will probably notice an improvement but there are better things out there. With a stereo headset I just noticed that everything sounds "fuller" is the best way I can describe it.

Also Razer uses the software to collect information and sell it to others, so it's really up to the individual to decide whether or not it is worth it.

I love how their demo, in the non-surround one just has all the bass cut from it.

Anyway, it basically knows where the sound should be (because the game is actually rendering a 3D environment) so it applies algorythms to the sound (Dolby and DTS have these as well) that give the impression of surround. This is done by adding delays to sounds that should be played from both headphones as once (e.g. if something happens to your left, there should be a fractional delay when hearing it in your right ear) and other magic-like science.

A good example of this would be this - which is done with two microphones instead (as it's not a game, it's real life).