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?
Fortunately, we now have more than my personal experience to offer in debunking this myth. Here are some:
1. Karl S. Kruszelnicki
The world is full of unproven "facts". You'll hear them in a pub after a few drinks with some mates. You will probably read them in an email from a well-meaning friend within the first month of your getting onto the Net. Or sometimes, you'll hear them debated on talk-back radio.
In 2003, one of them was scientifically debunked at Salford University in northwest England, at the annual meeting of the British Association for the Advancement of Science. It was that old favourite, "A duck's quack doesn't echo, and nobody knows why."
This question came up a few years ago on my Science Talk Back show on the ABC's Triple J radio. My honest answer was that I really didn't know, because I hadn't read any research on the topic, but on the face of it, it sounded like a ridiculous claim for three reasons.
First, each of the many species of duck has its own different quack. In fact, to make it more complicated, there are gender differences in quacks. For example, the female mallard duck makes a loud honking quack, while the male mallard duck makes a softer, rasping quack.
Second, most species of duck like to hang around on the water - usually out in the open. There are not many hard reflective surfaces near most lakes, so you don't get many echoes, anyway.
Third, why should the quack of a duck (alone, of all sounds ever made on our planet) have some magical property that makes it echo-free?
Then a Triple J listener rang in with what the Intelligence Community calls "Ground Truth". His family owned a duck farm, and he assured me that the quack of their ducks most certainly did echo off the walls of the sheds.
And that's where our understanding with regard to Ducks' Quacks rested, until Professor Trevor Cox from the Acoustics Research Centre at the University of Salford reported his research with Daisy the Duck one September. There was nothing special about Daisy - he just rang the local farm until he found one (Stockley Farm) that would lend him a willing duck.
2. Trevor Cox
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
Professor Cox is hoping to use this knowledge in improving echo-ridden environments, such as railway stations and restaurants. And I guess that the original myth about the sound of the duck's quack being echo-free is just quackers...