I have a tendency to get “yelled” at by my partner when I wake her up by restarting my computer in the wee hours in the morning. I recently discovered a way to disable the boot chime using some Terminal commands.
You’ll need to be an administrator of the computer for the command to work. Go to your Applications folder, then to the Utilities folder and launch Terminal. Type the following in, then press enter, then enter your administrator password:
sudo nvram SystemAudioVolume=%80
To reset it back to normal, enter the following:
sudo nvram -d SystemAudioVolume
As always, with these Terminal tricks, use at your own risk.