I have to wonder if the loose bolts are an additional problem not really related to the door falling off. Bolts should have lock wire keeping them in place. Even if they are loose, a door could be rattling or hissing air, but I’m not sure how it comes off. I’m not an ME, or a manufacturer, so I could be wrong, but if so, I’d like to know how that happens.

15% more flour looks like the best version to me.

Why wouldn’t sound travel across water? Why wouldn’t sound travel upwards as well as horizontally?