If the wave source or receiver is moving, the waves will appear to have a different frequency. For example if you are moving towards a sound source you catch up with the next peak in the wave sooner t...If the wave source or receiver is moving, the waves will appear to have a different frequency. For example if you are moving towards a sound source you catch up with the next peak in the wave sooner than you would expect because you are moving towards it. This effect is called the Doppler Shift and occurs for both light and sound.
