I should heave prefaced my post with what I meant by bantam ducks, LOL. I meant the Aussie Spots, the Mini Appleyards, etc... I did not necessarily mean Calls, but it is interesting the lady told you that Annarie. I am probably not the best person to talk to about Calls because I have not raised a lot of them in the past. I do have a couple dozen Calls now though and I am really shocked at how quiet they are. I have always heard that Call hens are so loud. I never hear a peep out of any of mine (I have probably just been lucky so far though, LOL).
As far as the other bantam ducks previously mentioned that I have kept for a number of years, very few of my hens quack (certainly nothing like some of the larger breeds I have kept like Welsh Harlequins, Swedish, Campbells, etc...). I certainly couldn't sex them as youngsters based solely on sound. I still think that tameness has a big impact on how loud a domestic duck is. I know I have mentioned that before and a couple people here told me I didn't know what I was talking about, LOL. I have seen time and time again though that my loudest birds are the ones that were usually raised in smaller groups and are tamer individuals (hence someone that only keeps a small flock of pet ducks may notice a lot more loud quacking). The reasons for this should be obvious to most people that have studied animal behavior. Most of the birds that I have bought as adults (usually from larger farms) literally hardly make a sound.