I've not seen it addressed, so I am asking: has anyone tried to fill the gap above the bathroom door? I am trying to think of ways to close it off without harming the walls or ceiling, but can't think...
X2 on the leave it as is. Bathrooms make noise. That's just the way it is when `roughing it'. or stuff foam into the space that will have to be removed when the door is opened. The foam will fill the gap but will not keep out the noise; assuming that is the problem.