At the moment there seems a larger issue no VPS Updates yet today, so the sound isn't going to be
The streaming updates are working away, but still waiting for VPS. Whilst typing this up I got a pop-up that promoting the avast! Mobile Security informative pop-up. No avast voiceover.
These informative/promotional toaster pop-ups appear to be piggybacked to the VPS Update Notification, so you don't see the VPS update notification, I suspect it is this that is screwing up the avast sounds on update notifications.