How to disable Windows system sounds - permanently - but not application sound

Solution 1:

In Windows Vista and later, you can control per-application sounds, including system sounds. Click the volume icon in the taskbar, then click on "mixer".

Click the mute button under "System sounds". Applications' sounds will still play, but system sounds will not.

Solution 2:

OK, I went to the folder where all system sounds were stored, and moved the entire folder elsewhere, so if it does change system sound schemes, it won't have a source to play the sounds...

On Windows 7 and Windows 10, the folder is: C:\Windows\Media

The other option is Sound Sentry...In the accessibility control panel, you can choose to have all sound disabled and, optionally enable visual cues instead.

From TenForums:

https://www.tenforums.com/tutorials/71209-turn-off-sound-sentry-visual-notifications-windows-10-a.html