I am frequently asked what my fascination is with ducks. A simple answer is that I grew up close to an artificial lake with a sizable duck population and that I visited frequently into my late teens so there is a great deal of nostalgia at work. As an aside, I will note that going to visit a duck pond, particularly with appropriate food, is great date material. I always imagined when I retire I would have a house by a lake with a sizable duck population.
A more thorough answer is that I find ducks to be a) always cute, b) seem unlikely, c) curious and silly, and d) they are capable of bonding very well so they make great friends.
Here is a page of many different duck species, with audio. Here is an Wikianswers on the oft-repeated myth that quacks don’t echo. Here is some of the math behind acoustic theory.
Ducks and Economics 