The Guinea Fowl in my neighbourhood are relatively quiet. In my experience, a female seems to only call when she becomes separated from her mate and can not see him; and then he is usually just around street corner or on the other side of a solid garden wall. The males only call when they are in mating mode and then only because he has lost sight of any other Guinea. Otherwise they do "talk" all the time, in gentle whirls and whistles, but it is so soft that you have to be just a few metres to them to hear it, and then you have to listen carefully. It could be that it is a survival thing? ...because it serves them to be quiet during hunting season here? I am just speculating.