Myth: Duck’s quack has no echo
Posted on March 14, 2018
Since I was a little boy, I have heard many times that ducks do not produce any echo when they quack. With the arrival of the internet, this myth has been amplified, so the general public started to think that this was true. I have been teaching my students about the electromagnetic spectrum these days, and we had a lesson about sound and its properties. So let’s start with the basics:
What is sound?
Sound is a vibration that propagates (moves through) a solid medium. For sound to be, particles of gas, liquid or solid have to vibrate. Therefore, sound cannot be produced in the vacuum of the space (hence the famous Alien movie motto “In space, no one can hear you scream“).
As sound is a wave, it present the typical characteristics of a wave: amplitude, wavelenght, frequency and speed. Moreover, as any other wave, it is subjected to be reflected when it hits a hard surface. That is what we call echo (the reflection of sound when it hits a surface). How many of you have ever scream ECHO! in an empty room, to hear your voice been replicated and thrown back at you with a slight delay? Everyone does this, and our impulse to scream ECHO! rises dramatically in places where we have to be silent (museums, libraries…).
So is there anything special in the duck’s quack that make that it works differently to all other electromagnetic waves?
Not really. Professor Trevor Cox from Salford University’s Acoustics Research Centre put this myth to the test. He made his duck friend Daisy quak in an anechoic chamber (which kills all echoes of any sound), and in a reverberation chamber (which amplifies the echo of any sound). The results were as expected: quack produces an echo. However, this echo is often masked by the quack itself, giving the impression that it is not present. However, the data analysis with proper instrumentation shows the clear fingerprint of an echo in the quack sound. As it happens very often with this kind of myths, it is just another case of cognitive bias.
You can read more about this, and also hear some clips of Daisy’s stellar performance here. You can also visit the website of Professor Trevor Cox’s group where they describe the experiments following this link.
- S Prev