Why don quacks echo?
My take is. Based on high research input. If you listen in to the quack of a duck, you will hear a slight intake of air immediately proceeding the quack. This denotes the fact that ducks inhale during quacking. Therefore there are no outer reverberations from the mouth, skull cavity, sinus cavities, and bones to your lungs, throat, stomach, etc. which is covered by layers of insulating muscles and fat and tendons. Thus, a reverse echo effect.
