Tuesday, 28 January 2014

A quackpot myth

On 7 February 2014, a new television comedy panel game show begins (or began, depending on when you are reading this) on Sky1, presented by Lee Mack, one of my favourite comedians. In each of the eight episodes, three celebrities aided by in-house boffins present weird “facts” and attempt to prove whether they are true.

The title of the show is Duck Quacks Don’t Echo. This is a reference to a popular belief that, er, duck quacks don’t echo.

The idea that the quacking of a duck does not reverberate, and that nobody knows why, has been widely repeated by such authoritative sources as Twitter feeds, online blogs, email trivia lists and even fruit drink bottle caps. The concept is, of course, completely quackers. Why on earth would the call of a duck be exempt from the acoustic laws that apply to all other sounds? 

But the myth is not so crackers that it has been ignored by academic researchers. I learnt recently that a few years ago acoustics scientists at the University of Salford investigated this fantasy with the co-operation of a duck called Daisy (species not disclosed, but presumably a farmyard-type Mallard), which they had recruited from a Cheshire farm. (I have no idea who was stupid enough to fund the research.) 

When Daisy was recorded quacking in an anechoic chamber and also in a reverberation chamber, it turned out that there was no echo in the former (which is, of course, why it is called anechoic) but a reverberant echo in the latter. Surprise, surprise!

If you wish, you can listen to samples of Daisy Duck’s various echoic and anechoic quacks at www.acoustics.salford.ac.uk/acoustics_info/duck

Sadly, shortly after the university relieved Daisy of her scientific duties and returned her to her farm, she became dinner for a local fox and has therefore quacked no more. 

But how did the quackpot duck-quacks-don’t-echo myth arise? 

One theory is that although quacks may echo, ducks rarely loiter near suitable reflective surfaces. An echo is only generated if there is a nearby smooth surface, such as a cliff face, positioned at an appropriate angle to bounce the sound back to the listener. 

A second theory is that because quacking ducks — such as female Mallard and Gadwall — tend to quack fairly quietly, their echoes are too quiet to hear. 

No comments:

Post a Comment