Why is it that the closer you go to a sound, the higher the pitch? I don't understand why the answer is that the sound waves reach you faster. I thought pitch was how close the peaks of the waves are, not how close you are?
Answers
The pitch of the siren of a Fire truck appears to change as the truck passes us due to the Doppler effect. Of course, to an observer on the truck, the pitch does not change at all. Since the speed of sound in air is essentially fixed, the perceived pitch of a tone is related to the wavelength of the sound. A high pitch sound corresponds to a high frequency sound wave and a low pitch sound corresponds to a low frequency sound wave. So either it is a high pitched sound or a low pitched sound it would travel at the same speed.they all travel at the speed of sound. The speed of sound varies with pressure and density, but you can approximate to 330 m/s in air.
If you appear to hear high pitch sounds faster than low pitch ones, this is probably because of doppler shift. For example, a car approaching you has the sound waves compressed together because the motion of the car is towards you: this creates an apparent rise in pitch, whereas once the car has passed you, the sound wave coming from it is effectively stretched out as the source of the noise (the car) is retreating at the same time as the noise is coming towards you. This makes the pitch appear lower.