Actually, the cabin is not noisy per se but it is certainly true that as the plane is significantly more silent than all the other, you can hear all cabin noises much louder! A crying baby on a 380 is therefore far more audible than on any other aircraft as is crew service.

It is very much like noise-cancelling headsets. While they decrease background noise, they make the snoring neighbour or talking one far more audible than when you take them out!