Rural areas are obviously overall quieter, but that's not very relevant because we can't have 100% of the human population living in rural areas. That's impossible.

My overall point is that cities/suburbs that have fewer cars have less noise, and that reduction of the usage of individual vehicles is a major contributor to city noise. Just compare decibel levels standing in a residential block of the Upper East Side or inside Central Park versus the exit of the Lincoln Tunnel.

The loudest noise ain't coming from the HVAC and elevators, nor the underground subway.