I am using a MacBook Air (Mojave, 10.14.6), and I want to permanently disable the awful Startup Sound ("chime"). I tried any of the following commands:
sudo nvram SystemAudioVolume=%80 sudo nvram SystemAudioVolume=%01 sudo nvram SystemAudioVolume=%00 sudo nvram SystemAudioVolume=” “
After each command, I did a shutdown of the Mac, and started it up again (no reboot). In all 4 cases, the startup sound was still played after I turned on the Mac.
How to permanently disable this sound? I do not want to hear this sound in any circumstances, like
- whether a headset is plugged in or not
- whether the audio volume is zero or non-zero
- whether I am rebooting, or shutting down and turn on again
- whether the Mac is powered or unpowered
- whether the time or day of the week
I hope it is clear.