Could you come and explain to our neighbours that by all accounts we shouldn't be kept awake by their baby crying at night given they live on the other side of a big, thick, loadbearing wall between two Victorian houses?
I know this wall business is totally unimportant in the grander scheme of things, but I've lived in a number of flats converted out of 19thC properties and the extent to which sound travels is extremely variable, even when you're dealing with the original loadbearing walls - even in the same property it can vary a lot. Sometimes there seem to be 'leaky' spots - we used to have a problem that our neighbour was getting disturbed by my radio in the morning to the extent it was waking him up. We moved the radio three inches to the right, and now he doesn't hear it at all.
All I'm saying is that although we're not talking about paper thin walls where you'd hear a spider walking across the room next door, sound might still travel more than you'd expect.
Sorry I'm going on about it again....I know it's irrelevant really!