None of our Muscovies "honk". I need to record some of the different noises they make and post them here! Well, guess I know what I'll be doing today...
Anyhow, here's what we've heard - females make a soft twill or coo sound. @Miss Lydia really does explain much better than I ever will. Drakes on the other hand hiss. I have heard our females kind of honk when running away from something stressing them or when fighting with each other. I have a very hard time calling it a honk but that might be the closest to the way to describe although a cough might also describe it.
Now, to find that mic and voice activated recorder...