This is about the noises from the shower that might come into the children's room and could wake the child.
Phew... do you already have children? A baby can’t be woken up by anything at all... and then comes the phase where the baby has to get used to noise so that it can cope with sounds. And if you do everything wrong, the toddler can’t sleep because it hears a pin drop unusually loudly.
Of course, you can follow Sebastian Lexmaul and a) first focus on the thickness of the wall, b) the quality of the door, and c) then the material of the wall. Maybe also leave out the wardrobe, the resonating body... that was a joke.
Personally, I would pay attention to good doors, that’s what you should do anyway... bathrooms are always doubly boarded in timber frame construction, and the other variations are also walls that have their reason for existing.