wind from certain relative directions can be really loud, even if you're not riding fast. I don't usually have a problem, but I have had a few rides in open country where it's painful. Headgear probably matters for that, too, since it can cause eddy currents around it.
My modern bike with an Alfine IGH is totally silent, until I touch the brakes, which squeal if used lightly. I sometimes get a bit creeped out by that, especially at night. Maybe I'll have to put a baseball card in the spokes.