In Zurich right now and just want to say: quietest big city i ever been to. Only clocks are ticking!
Agreed, as most of the buildings have great insulation or double-pane windows. Though during the summer, just don't have an open window facing a major inclined street like Universitätstrasse with constant tram and vehicle noise, and high revs up the hills (this is a major problem in SF, except many buildings are thinner and less updated).
In Switzerland, one issue is the older churches ringing their bells every 15 minutes 24/7. The Swiss Noise Council is trying to limit the bell-tolling to day-time hours.
http://www.swissinfo.ch/eng/for-whom-toll-the-bells-_church-...
Here's the example for daytime traffic noise: https://s.geo.admin.ch/722d116dec