text: the doppler effect? if i am standing in a train station and a train approaches and then continues on through the station, the frequency of the sound of the train will: a) rise and then fall, b) rise steadily, c) fall steadily, or d) fall and then rise.  i disagreed with my incompetent physics teacher on this question. as a signal is being advance towards you it will rise in frequency.  like wise as it emitting object goes away the frequency will decrease.  think of the sound waves as a slinky as the coils get push closer to you they close-up.  when you grab the other side and pull it away from you the coils open up.