A lot depends on the individual duck. It seems like my loudest ducks are the most friendly individuals. The birds I have bought as adults from larger breeders are generally not as loud it seems. The loudest breed I have had in awhile were Welsh Harlequins. A couple of mine were incredibly loud. I also have a few Mallards that will just about pop your eardrums. My Runners are, overall, not as loud as some of my others (but I do have a couple Runners that are extremely loud). All the rest of my large breeds have been middle of the road as far as noise.
My bantam ducks, for the most part, are relatively quiet. I never hear a peep out of most of them. In actuality, the Calls that I have are also fairly quiet. I think I have just been lucky so far with those because they are known for being really loud.