# When an automobile moves towards a listener, does the sound of its horn seem relatively low pitched, high pitched or normal?

Mar 9, 2018

Higher than normal pitch.

#### Explanation:

The peak of the sound wave that arrives at $t = {t}_{1}$ did not have to travel as far as the previous peak did because the car came closer. That means that the time between the 2 peaks was less than if the car was standing still. Frequency, $f$, is

$f = \frac{\text{number of peaks}}{t i m e}$

Therefore the frequency you heard was higher than if the car was standing still. Higher frequency means higher pitch.

I hope this helps,
Steve