SDB:Disabling the system bell
A loud noise is produced by your computer when doing certain things, such as holding Backspace for too long when you're clearing all text at a terminal prompt. Even if you mute all sounds, it is still played. The sound is not coming from the sound card, but from inside the PC.
You can only disable the system bell for a given user account. Open .inputrc in your home folder. Uncomment the following line:
set bell-style none
Then add this to your desktop environment's autostart scripts:
xset b off