constant background noise

i get a constant background noise from my speakers, its difficult to explain, its like a rapid rasping sound even when i do nothing, its worse when i move the pointer or scroll up or down. its not loud but annoying, its not affected by the volume controll.

Welcome
Do you get the noise in Safe Mode. If yes its your computer
If no
Can be many things
sound card/drivers etc

Lets try to figure it out
Try in safe mode. If still there report back, if gone try a clean boot
How to troubleshoot a problem by performing a clean boot in Windows Vista or in Windows 7