A simple way to turn off the pc-speaker bell is to edit the file /etc/inputrc

And just add the lines (just verify that there is no other line about bell-style)

# do not bell on tab-completion
set bell-style none
set bell-style visible

The first line says no beep, the second line makes the console flash instead … if that is left out the console doesn’t flash 😉

Reload the file (I just rebooted) and all should be well.