Subject: A Duck's Quack Doesn't Echo? Surely a hoax?

This would probably come somewhere between "acoustics" and "zoology".

Several friends have sent me a list of "fun" trivia which is making 
the rounds on the Internet these days. Most of the items are true, 
some are clearly false, but one particular item is particularly 
annoying, because I've been unable to find anything on the Internet 
which supports or refutes it:

"A duck's quack doesn't echo, and nobody knows why."

This definitely smacks of a fabrication, as sound is sound, and sound 
bounces off any hard surface-- doesn't it?. The "nobody knows why" 
part is particularly egregious, as I think we know quite a bit about 
sound-- don't we? Ducks don't have "stealth quacking technology"-- do 
they? Not that I've seen many ducks standing at the mouths of box 
canyons quacking loudly, but still...

Re: A Duck's Quack Doesn't Echo? Surely a hoax?