Why is it that when a duck quacks it doesn't echo and it never does it is proven?

Answer 1

A duck's quack does echo. This urban myth flies round the internet and gullible people pass it on without thinking or checking. All sounds will echo including quacks. It has been tested various times, Mythbusters have done it, I have done it. A quack echoes very nicely.

Answer 2

Sorry, all sounds echo under the right conditions and a duck's quack is no exception. I'd be interested to know where you found this "proof"