Comment 10 for bug 343677

I think that to disable these sounds, you need to have gnome-settings-daemon (or another daemon implementing XSETTINGS) running, with the Net/EnableEventSounds setting set to (integer) 0. I see a Debian ITP for "xsettings-kde" at http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=512562; it looks like it's present in Debian Unstable currently. Alternately, I wrote a small implementation at http://code.google.com/p/xsettingsd/ that may be useful for people who aren't running a desktop environment.