Quacking duck

Question:

One of my students said that a duck's quack does not echo. I cannot think of an explanation for this, is it urban myth or is it true and if it is why?

Answer

Unfortunately I don't believe your pupil to be correct. Like you I can't see any reason why the sound waves from a quacking duck would be any different from those from those from another sound source as far as reflection and echoes go. It would be really nice to think that they were!

They could test it by having a real duck or if one of those is not 'available' they could try quacking themselves. I am sure that they would soon find that they could detect an echo. The school sports hall might be the place to start although the echo would be rather rapid.