*NOTE* When you use a headset or external speakers through the headset port or USB, the startup sound cant be muted! You have to remove the headset or speakers before closing down and reconnect after startup.
With SilentStartup its easy to (temporarily) mute the startupsound of your Mac. You can also indicate that you want to keep the sound muted after the startup. This comes in handy when you use the facility to start your mac automaticly and dont want to be disturbed by any sound. Its easy to unmute the sound manually after startup, in the usual way.