Possible Duplicate:
How do I change the start up sound?
Note: This is not a duplicate. The above question refers to the sound played at login and not the sound at the login screen.
Is there some way to change the sound that is played when the login screen is displayed? Currently it's a short drum beat.
Note that I am not referring to the login sound, which in Ubuntu 12.04 is no longer enabled by default, but the much shorter sound at the login screen.
