Disable startup sound
MacMini, Mac OS X (10.6.6)
MacMini, Mac OS X (10.6.6)

To everyone: perhaps this is late, but for what it may be worth, have a look at
http://www.robertcailliau.eu/Alphabetical/S/StartupSound/StartupSound.html
🙂
Robert.
have you tried this? works for me all the time if you are using external speaker or headphone
1st unplug your speaker then go to System Preferences, Sound, Check the "MUTE" box then plug your speaker back. You will notice that the "MUTE" will automatically uncheck itself after that just restart your mac & there you go no more annoying GONG sound."
thanks for posting this that noise was irritating me
Disable startup sound