Comment 3 for bug 34745

Upstream has the same opinion:

 Comment #5 from Behdad Esfahbod (developer, points: 21)
2006-03-27 00:38 UTC [reply]

Adding this to ~/.inputrc or /etc/inputrc works for example:

     # use a visible bell if one is available
     set bell-style visible

Something not quite irrelevant: I had a quite embarrasing moment when I booted
the GNOME 2.14 when I was in the office and its LONG login sound went as loud
as my speakers could. Well, I believe a default install should not make any
sound, and that should be set up through GNOME sound settings. Seeking a
solution in gnome-terminal's defaults doesn't look like optimal to me.