Anyone who has used the Internet more than a week has probably received at least one of those annoying lists of “facts”: dozens and dozens of items of no real significance that somebody thought would be cool for you to know. It is indeed fortunate that the lists are usually composed of items of no real significance, because many of the entries are of dubious veracity. The purpose of these lists apparently is not to educate the masses (however trivially), but to induce readers into the information age equivalent of a scavenger hunt, sending them scurrying all over the Internet in an attempt to verify the truthfulness of the entries. Ours is one of the virtual doors that gets knocked on quite frequently by these scavengers, and while we’re glad to help, our job is never done because anyone can make up lists like these: just invent four or five of the most far-fetched statements you can imagine, and follow them with the phrase “and no one knows why.”

To wit:

Ostrich eggs have no yolks, and no one knows why.

Julius Caesar was left-handed, and no one knows why.

Banging your head against a solid wall really hurts, and no one knows why.

The winner (so far) of the Most Ludicrous Entry contest is the claim that a duck’s quack doesn’t echo. Unfortunately, it’s also the item we’re most frequently asked about. The premise is just silly: a duck’s quack (and presumably, of all the sounds known to man, only a duck’s quack) has some special sonic property that causes it not to echo. We’re not talking about a situation where a landform creates an acoustic shadow (a phenomenon under which even loud sounds can be inaudible to nearby listeners), but the claim that a duck’s quack doesn’t echo under any conditions.

One of the main problems with such a claim is that the term “a duck’s quack” is non-specific. Different species of duck make different sounds, and there are a lot of breeds of duck in the world. And anyone who has spent time around ducks knows that even within the same species of duck, a male’s quack can sound nothing like a female’s. (Female mallards, for example, make loud honking sounds, but male mallards produce a much softer, rasping sound.) Do all these varied sounds, without exception, fail to produce echoes?

I could dismiss this one merely from personal experience. Although I grew up in suburbia, much of my youth was spent raising various kinds of domesticated animals, particularly ducks and geese. When our ducks got to quacking in unison, I could most assuredly hear the cacophony of sound as it echoed off the stone walls that surrounded our yard and entered my bedroom window. So could neighbors who lived a few hundred feet down the street and frequently called us to complain about the noise. The surprise was not that our ducks’ quacks didn’t echo, but that they echoed so remarkably well.

Fortunately, we now have more than my personal experience to offer in debunking this myth, as an acoustic research experiment carried out in 2003 by Trevor Cox of the acoustics research center at the University of Salford in Greater Manchester set this legend to rest:

Acoustic expert Trevor Cox tested the popular myth — often the subject of television quiz shows and Internet chat rooms — by first recording Daisy’s quack in a special chamber with jagged surfaces that produces no sound reflections.She was then moved to a reverberation chamber with cathedral-like acoustics before the data was used to create simulations of Daisy performing at the Royal Albert Hall and quacking as she flew past a cliff face. The tests revealed that a duck’s quack definitely echoes, just like any other sound, but perhaps not as noticeably. “A duck quacks rather quietly, so the sound coming back is at a low level and might not be heard,” Cox [said]. “Also, a quack is a fading sound. It has a gradual decay, so it’s hard to tell the difference between the actual quack and the echo. That’s especially true if you haven’t previously heard what it sounds like with no reflections.” He said ducks were normally found in open-water areas and didn’t usually congregate around echoey cliffs, which may have fueled the theory that their quacks don’t produce an echo. “You get a bit of reverberation — it’s distinctly echoey,” Cox said.

Trevor Cox expounds on this bit of research in his forthcoming work, The Sound Book: The Science of the Sonic Wonders of the World: