Boot up or restart your Mac and it’ll make the traditional “startup chime” sound”. This lets you know the Mac is starting up properly, but it isn’t appropriate if you’re booting up your Mac in a quiet location like a library, or if someone is sleeping nearby.
You can easily silence the sound on your next boot, if you know what to do. But silencing the sound permanently will require a terminal command that changes a hidden setting.
How to Temporarily Disable the Startup Sound
Your Mac’s startup sound depends on the volume level your Mac was set to when it was shut down. If your Mac was set to maximum volume level, the boot chime will be played at maximum volume. If your Mac was muted, the startup chime will be silenced.
To disable the startup sound, just press the “Mute” button on your keyboard (that’s the F10 key on a MacBook) before shutting down or restarting your Mac. If you ever have to restart your Mac for some reason but you don’t want it making any noise, just do this.
If you don’t have a Mute key on your keyboard, you can always just set the volume slider to the lowest level it will go. That accomplishes the same thing.
How to Permanently Disable the Startup Sound
To permanently disable the startup sound so it isn’t played at startup, even if you have your volume level set to maximum volume when you shut down, you need to use a terminal command.
To do this, open a Terminal window. Press Command + Space to open Spotlight search, type Terminal, and press Enter. Or, you can open a Finder window and head to Applications > Utilities > Terminal.
Run the following command in the terminal window:
sudo nvram SystemAudioVolume=%80
Enter your password when prompted and press Enter. Restart your Mac and you won’t hear the sound.
If you’d like to undo your change later and have the startup chime play normally when you boot your Mac, run the following command:
sudo nvram -d SystemAudioVolume
Help, the Command Didn’t Work!
Some people report that the above command doesn’t work on their Macs. If it didn’t silence the startup chime on your system, you may want to try running one of these other commands instead. These reportedly work for some people. This may be hardware-dependent, and certain commands may only work on certain hardware.
sudo nvram SystemAudioVolume=%01
sudo nvram SystemAudioVolume=%00
sudo nvram SystemAudioVolume=" "
(In the above command, that’s a single space character between the quotation marks.)
Many websites say you can silence your Mac at boot by pressing the “Mute” button on your keyboard and holding it down right after you boot the Mac up. However, this didn’t work for us. Perhaps it only works on older versions of Mac OS X, or with older Mac hardware.
Bear in mind that you won’t hear the startup chime when resuming from sleep or standby mode. That’s another good reason to just put your Mac to sleep rather than completely shutting it down, although everyone needs to perform a full shutdown occasionally–if only for a system update.