Yes, the demo has an audio track for the door knocks not sure why its gone XD

Yes tried mute then unmute and then manually turning volume down on each setting and it still did not work. Oh also to clarify, I am playing on PC and, similar to the previous to mine reply, the demo version's audio seemed completely normal. ( and just to clarify, I tried the full game first but tried the demo after to see if it worked and it did so there is not some sort of overlap bug or something messing it up lol)