[bombcar]

It varies by area; I remember staying in Brooklyn with a friend and being a few floors up the traffic noise was minimal (constant), few horns, but it seemed an emergency vehicle went by every few minutes.

Most of what I remember of European cities, too, when anywhere near the denser parts.

Part of "city noise" is dependent where you're living, and how new it is. Close, cramped, older building with people arguing above and below and beside you? Not fun. Newer building with excellent soundproofing? Nowhere near as bad.