The terminal bell seems to be disabled in Ubuntu 12.04, and to enable it the "pactl" (pulseaudio control) command needs to be used. For instance, in order to activate the "drip" sound as a terminal bell use the following command either on the command line or in .profile or .bash_profile:
/usr/bin/pactl upload-sample /usr/share/sounds/gnome/default/alerts/drip.ogg bell.ogg
In order to control the terminal bell volume use the following command either on the command line or in .bashrc:
/usr/bin/xset b 30
Reference: http://www.thinkwiki.org/wiki/Installing_Ubuntu_12.04_%28Precise_Pangolin%29_on_a_ThinkPad_X220
