I live in an apartment complex where children are not allowed to reside. Anyway, last month, a couple moved in downstairs from us. They are fairly young and the female stays at home most of the day.
Well, they have some hillbilly CD that they play
EVERY NIGHT around 11pm, for at least an hour!

It is the same song, on repeat. It's not unreasonably loud, but I can hear it pretty clearly.
Anyway, we had our surround sound on one day and were listening to some music. Well, these fools start banging on the ceiling. We just ignore them because we have been listening to the same song every night for about 2 weeks. So, we have no plans of cutting our music down on this occasion. So, the idiot comes to our door and says that our music is too loud and the baby just went to sleep...

what baby? Remember, there's a no children rule here.
So, I promptly tell the manager that there are children in the building. Well, the young lady says that she is just babysitting for a friend who went out of town...whatever...that baby has been there since move-in. They continue to knock on the ceiling sometimes, but I do not feel compelled to turn down the music for an illegal resident while I still have to listen to the same some all night, every night.