You can also turn off the "beep" sound system wide by editing:
using your favorite text editor (vi, pico, mcedit..) and add:
set bell-style none
Additionally create a file:
and add the following:
setterm -blength 0
Add this line to the file /etc/modprobe.d/50-blacklist.conf
Sometimes alsa creates a "beep" device. use alsamixer and hit F6 to see all devices. Mute the beep and then use "alsactl store" to save this config.