The Doppler Effect

I know this post is really late but here it goes anyway. This is a picture of my car steering wheel. From this wheel comes the power to blast a very loud car horn. This horn involves the Doppler Effect. The Doppler Effect involves the "perceived" change that a listener observes in frequency and wave length. As the object producing the sound (car horn) is moving toward the listener, the waves of sound increase in frequency as the waves are compressed with shorter wavelengths which gives the impression of a higher pitch horn. As the horn moves away from the listener the sound becomes a lower pitch as the waves emitted from behind the source have a lower frequency and longer wavelengths. This is the Doppler Effect.