New development in for example NYC has very strict requirements on how much noise can pass through walls, ceilings and floors. I live in a tower that was just f

New development in for example NYC has very strict requirements on how much noise can pass through walls, ceilings and floors. I live in a tower that was just finished in 2015, the floor-to-ceiling windows are double-pane glass (no air gap, looks very thin), rubber mounted rim all around. It's absolutely, completely, silent. I have never heard a single noise from a neighbor either. Open a window, the traffic noise from the street is intense (and messes up the climate control, so no need to do that). So, it's definitely possible to build densely with great soundproofing, and is now often required by the building code in bigger cities. Of course old stock won't be magically converted, but will also improve with time as they get renovated.