The Factory Whistle

QUESTION:

Does the wind affect the pitch of the factory whistle you hear on a windy day? If so, why? If not, why not?

cartoon of a whistle blowing

ANSWER: NO

The wind does not affect the pitch. The wind does affect the speed of sound because the medium that carries the sound moves. But the wavelength of the sound changes accordingly, which results in no change of frequency or pitch. This can be seen by analogy:

Suppose a friend is placing packages on a conveyor belt, say at a frequency of one each second. Then you, at the other end of the belt, take off one package each second. Suppose the speed of the belt increases while your friend still places one package per second on the belt. Can you see that the packages (farther apart now) will still arrive to you at the rate of one per second?

drawing of a slow belt and a fast belt

Back to question