I checked the manual already which is why I was surprised.
In any case, sorry for the double post. Admins can delete this if they want, but I figure I would post what was triggering this.
My problem was that I run a custom program when an alert is triggered. The program uses curl to alert 2 kodi boxes I have to login and display a live view of the camera on 2 of my TV's. This is very convenient for instantly seeing on your TV what is going on when an alert is triggered. No need to pull out your phone. In any case, it turns out the "pop" sound I was hearing was the notifications of the user from the Kodi boxes logging in.