Sound and Music - Mission SM4 Detailed Help

The Doppler shift involves a shift in the ____. List all that apply ... .

Definition of the Doppler Shift:
The Doppler shift is the alteration of the frequency observed of waves that occurs whenever the wave source is moving towards or away from the observer (or the observer is moving towards or away from the wave source).

When a wave source moves towards an observer, the frequency that is observed is different than the frequency at that waves is produced. This is known as the Doppler shift. But this shifting of the pitch is not the only thing that is heard. There is also a very noticeable change in the intensity of the sound. As the wave source approaches, the sound intensity increases (it sounds louder) and as the wave source departs, the sound intensity decreases (it sounds softer). But don't be fooled! This noticeable alteration in the intensity (perceived as loudness) is not the Doppler shift. The intensity of a sound is inversely proportional to the square of the distance an observer is from the source. So as the distance decreases, the intensity increases.