How to Mute the Mac Startup Sound
Many Mac users are fond of the Mac startup sound that chimes on system boot, but there are definitely times when booting that you’d rather just be quiet, say a library or coffee shop. Thus, we’re going to show you how to mute that boot up sound on any Mac, MacBook model (Pro, Air), iMac, or Mac Pro, we’ll offer a temporary solution, and a few different permanent solutions to mute the sound as well.
Temporarily mute the Mac startup sound
If you want to temporarily stop the Mac startup chime sound, just hold down the Mute button on your Mac keyboard, this will silence the boot sound for that particular system boot/reboot.
Note the mute key is going to be different on various Macs, sometimes it has been F3, F10, and on the newest Mac portables, it’s F9. The key looks like a speaker pointed sideways, if you press it while the Mac is turned on you’ll see the following screen:
Note that you will not see that mute logo when the Mac startup has begun, it will simply just be quiet for the startup whenever the key is held down during boot.
Permanently Mute the Mac Startup Sound with Terminal
With the Terminal app you can completely silence the startup sound and mute it so that it will completely quiet. Open the Terminal app (found in /Applications/Utilities/) and issue the following string:
sudo nvram SystemAudioVolume="%00"
Hit return and follow it up with the admin password to allow the adjustment, that is required by sudo. This quite literally disables the chime, until it has been undone at least.
You can restore the startup sound to its default by using the following command string:
sudo nvram -d SystemAudioVolume
A reboot is necessary for user to notice the change, of course.
Mute the Mac startup sound all the time with an app
If you want a more permanent solution to shut your Mac boot sound up, there’s a preference pane that does just that. WIth StartupSound or StartNinja you can adjust the volume of the startup chime or mute it completely.
Obviously the newer versions of OS X will want to use the StartNinja app if you want to completely stop the boot sound all the time, which will apply to every boot of the Mac, not just a temporary muting like the first solution offered. Enjoy your newly silenced boot, whichever way you go.