This, at least in America, is the real heart of the problem. Our building practices have leaned so cheap for so long on thin margins, that walls, even exterior,

This, at least in America, is the real heart of the problem. Our building practices have leaned so cheap for so long on thin margins, that walls, even exterior, are paper thin to the point of being ridiculous. This becomes much more obvious if you have travelled around to other countries, and it's not all about wealth. Yes, rich ones such as Switzerland are a great example because of the heat containment requirements they have, there are poorer countries that still know how to build a house without sound going through it as if it was nothing. This doesn't mean noise pollution shouldn't be tackled itself, but cities are noisey, and people at least deserve to have domiciles that give them a refuge. This means you need to start participating in your city and county governments if you really want change (like many things!)