Psst: Silence your startup sound
Who has time to turn down the sound down before restarting your Mac? If you answered “not me” to that statement, then Satsumac Software has a piece of software for you.

Psst can silence the startup sound, or if you really want it can max out the volume as well. This software might fall into the “questionably useful” category, especially when reading the warning on the Satsumac Software page: Important: The method Psst uses to change the volume does not work on every model… .
The good news is that it worked on a Macbook Pro without much issue, using virtually no CPU and 6 MB of memory. Perhaps if you simply remember to turn down the volume down before shutting down or restarting this app isn’t necessary. Uninstallation is a little messy, the app installs two preference files, runs a deamon file on startup and needs to be uninstalled with their custom uninstaller (or AppZapper). You can grab your copy of Psst here.

Or you good just mute your sound (F3 key on the keyboard) before restarting. The Mac should make any noise
*shouldn’t make any noise.
Great for absent minded folk like me.
yeah… “shouldn’t” being the operative word. You dont wanna be the one sitting in the library on campus booting up the mac with the suposed f3 action to disable the sound and alert everyone sitting within an earshot of you that you booted your mac.
Like this fellow… http://www.prangstgrup.com/startupsound/
Yes(sssssss).
Downloaded.
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[...] with their StartupSound.prefPane. We have reviewed apps before that silence the startup chime, like Psst, but none of them have been quite like this one. This app, unlike other silencers, comes in the [...]