The Doppler effect is a change in the ______of a sound.
pitch
Correct! The Doppler effect is a change in the pitch of a sound. To understand how the Doppler effect affects the pitch, we can consider the example of a moving siren.
When a stationary siren emits a sound, the sound waves propagate equally in all directions. However, when the siren is moving towards you, the sound waves get compressed, leading to a higher pitch. This is because the frequency of the sound waves appears to increase as the source of the sound approaches you. On the other hand, when the siren is moving away from you, the sound waves get stretched, resulting in a lower pitch. In this case, the frequency of the sound waves appears to decrease as the source of the sound moves away from you.
So, the change in the frequency of a sound due to the relative motion between the source of the sound and the observer is what causes the change in pitch, known as the Doppler effect.