The Doppler effect is sensitive only to motion along the line of sight.

Question

Quizplus · Accepted Answer

The Doppler effect is based on the change in frequency or wavelength of a wave caused by the motion of the source or observer relative to each other. It is most noticeable when the source is moving directly towards or away from the observer along the line of sight. Other types of motion may affect the wave in different ways, but the Doppler effect is primarily sensitive to motion along the line of sight.

The Doppler Effect Is Sensitive Only to Motion Along the Line