I have tried and tried to get the system beep working, but with no success.
I have selected System-->Sound-->System Beep-->Enable Audible Beep (from the Gnome Desktop) I have tried from a Terminal window Edit-->General Tab-->Selecting terminal bell checkbox I have tried entering modprobe pcspkr at the command line.
Trying echo -e '\a' or using the beep application - Nothing works!
I know my hardware speaker works, because if on startup the battery is low it will beep.
Update: It is a laptop computer. It is an IBM Thinkpad, iSeries.
I did look at the modprobe blacklist, and pcspkr was not listed.