No startup / boot chime; how to bring it back?
Consider trying this out:


Launch Terminal.app and type the following command:

sudo nvram StartupMute=%00
If prompted enter the admin password.
Quit the Terminal app..
Make sure the volume is up before you restart your Mac.
Restart your Mac.


You should hear a F-sharp chord sound when your Mac boots up.

If you wish to disable it, follow the same steps as above and type the following command instead:

sudo nvram StartupMute=%01

Tested on a 16" 2019 MacBook Pro running macOS Catalina 10.15.3