Mysterious notification sound

Hello. Since this afternoon, I'm having the System notify sound of Windows, with no reason. Notification center is empty.
Where can I see what is happening?
It's the sound at 2:55 in this video, called "Windows Notify System Generic"

Settings / System / Notifications & Actions ... under Get notifications form these senders, check to see if one of them has only Sound enable. You can Click on each one to see the Notifications Options available.