Hello Sussmith,
The tutorial below can help show you how to turn off notification sounds in Windows 11.
https://www.elevenforum.com/t/turn-on-or-off-notification-sounds-in-windows-11.3534/
However, you can use mute below to not hear anything until you unmute.
https://www.elevenforum.com/t/mute-and-unmute-sound-output-volume-in-windows-11.2357/