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