Disabling the PC speaker in Ubuntu

Temporarily :

sudo modprobe -r pcspkr

Permanently (for the life of the OS)

append this

# disable pc speaker beeps
blacklist pcspkr

to

/etc/modprobe.d/blacklist

perhaps via

sudo vim /etc/modprobe.d/blacklist

or

gksudo gedit /etc/modprobe.d/blacklist