Changes in which property are heard when the Doppler effect occurs? pitch amplitude volume wavelength

The change in observed frequency of a wave when there is relative motion between the wave source and the observer. It was first proposed in 1842 by Austrian mathematician and physicist Christian Johann Doppler. While observing distant stars, Doppler described how the colour of starlight changed with the movement of the star.

Explanation:

To explain why the Doppler effect occurs, we need to start with a few basic features of wave motion. Waves come in a variety of forms: ripples on the surface of a pond, sounds (as with the siren above), light, and earthquake tremors all exhibit periodic wave motion.