Why does my female duck make so much noise?

  I have two call ducks .. one male and one female .. recently my female duck has been quacking really load every 20 minutes ... this can be a problem as i have neighbors, which are woken up when my ducks make noise .. . i wanted to know .. why she is making the noise and if possible i could stop her making it ..
maybe the duck is stressed or it will quack a lot when it is breeding to protect itself and the eggs or ducklings ....