To get rid of the annoying pre login gdm 'music' in Ubuntu 11.04 just open the 'Startup Applications' from the Control Panel
- click on the logout button on the top right - then select 'System Settings' to get to the Control Panel
Then just untick the 'GNOME Login Sound' option - refer image below
and then option the terminal/commandline and execute this command
sudo -u gdm gconftool-2 --type=bool --set /desktop/gnome/sound/event_sounds false
restart and you won't get those annoying drums
-- old posr --
One annoying issue in Ubuntu 11.04 is that there is no GUI to disable the pre-login sound that GDM (the Ubuntu login screen) makes when it opens. This 'music' becomes an issue when you work in a quiet environment
from the command line execute
gksudo gedit /etc/gdm/custom.conf
and add the line
SoundOnLogin=false
and the [daemon] line
save the file and restart - now you won't hear the pre-login 'music' at the login screen