How to disable the Startup Chime on my Mac

[MacGuy]

At for me, the Startup Chime is really annoying in both public and quiet place. How do I turn it OFF?

[Digger]

It’s simple. You must Launch the Terminal (found in /Applications/Utilities/) first. Then use the following command lines to either disable or enable the Startup Chime.

Disable:

sudo nvram SystemAudioVolume=%80

After Hitting Return/Enter key, you have to provide your admin password when requested

Enable it again:

sudo nvram -d SystemAudioVolume