If you want to turn discretely to your Mac at the library, in the transport or during a meeting, then this tutorial is for you.
Why a Mac beeps at startup ?.
A sound emanates from your Mac during startup, even when headphones are connected, because the external speaker is the default output of the chime (chime, in French). This melody indicates that the ignition of your Apple computer has completed successfully.
The trick would then be to lower or mute the volume by pressing the Mute key (F10), before turning off your Mac. Still need to remember to do it..
Permanently remove the sound of a Mac at startup.
If you have a tendency to forget to lower the volume, then we suggest you disable it permanently. To silence the chime for good, you have to go through the Terminal and follow these 3 steps :
Open the Terminal (Finder → Applications → Utilities → Terminal).
In the Terminal window, type the command, respecting the spaces and uppercase letters : sudo nvram SystemAudioVolume=%80.
Enter your password, and then press Enter.
Now, your Mac starts silently until you decide to reactivate it.
If you want to go back and re-enable the chime, open the Terminal, enter the command : sudo nvram -d SystemAudioVolume, press Enter , and lastly type your password.
If, however, you do not want to disable the chime so it is recommended to put your Mac to Sleep rather than turn it off completely (especially if you think the re-use shortly after).