WinMute

from https://github.com/lx-s/WinMute :

WinMute is a small and simple tool, that automatically mutes (and unmutes) your workstation based on triggers, e.g. the screensaver starts, or your bluetooth headphone disconnects.

Features

WinMute can automatically mute all sound devices on your workstation when:
you lock your workstation.
the display turns off.
you log off or switch user.
your workstation shuts down, goes into hibernate or goes to sleep.
your bluetooth headset/headphones disconnect.
your workstation is connected to a particular wireless network.
alternatively: your Workstation is not connected to particular wireless network
WinMute is small and only needs a few kilobytes of disk space
WinMute is ad-free, telemetry-free and generally does not send any data whatsoever