My Khaki's are almost silent until I get home from work and they are still locked up in the pen, then they let me know it's time for them to be let out. after they are in the yard I have to go look for them every so often just because I can't hear them... the females make some noise while foraging but other than that they are quiet. Oh and I've not had other breads before these Khaki's but mine do fly, so just keep that in mind (they are true Khaki's), my male can fly from one end of my 2 acres to the other without losing any altitude. Females are a little heavy at the moment though because they still have eggs in them. Very friendly though. But they will make noise if they see you or get spooked.
My chickens are very quiet compared to my ducks. I live in the suburbs and I'm on good terms with my neighbors and they say that my ducks don't bother them. I have 2 runners, welsh harlequin, white later and a cayuga. I find that it depends on the actual duck not breed as to how load they are. I did notice that they got really loud when they were "teenagers" and quieted back down once they hit 20ish weeks. Some KC can fly since they are lightweight. None of mine can. Also runners are lightweight but cannot fly at all and are good layers.
