My bathroom vent will also face the road, and I don't want to carry that noise into the house. What kind of duct will be the quietest? I think the thin, ridged metal tubing would be the loudest. I'm thinking the flexible stuff (like dryer vent hose) will be quieter? I know it has more resistance but its a short run and the fan is plenty powerful for the room its in. But I was definately going to insulate the pipe, is the flexible stuff insulated? It felt pretty thin when I was looking at it in the store.
Also I was planning on getting a plastic vent for the roof, I think that should be quieter than a metal one?
Thanks for any help. -Ryan