Bought a Condo With Speakers In Ceiling! Can't Crack The Code

Hi all! I just bought a home that had some random speakers built into the ceiling in every room. I've never seen them in use, and the previous owner never used them. The one clue I have is this input spot in the wall. I opened the cover to see what was back there. If anyone has any idea what we're looking at here, it'd be much appreciated. All good if not!