I was having a discussion with a friend about ***supersonic flights***. 

[![Concord][1]][1]
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It was then when he proposed an idea on an interesting experiment that can be done during a supersonic flight. 

***The experiment goes like this.***

- You board a supersonic jet along with your friend. The flight is cruising at **Mach 1** above Amazon rainforests, or some other place with comparatively low air currents.
You have somehow got the permission to do the experiment which involves *getting out* of the plane. 

- You both take all the safety measures and stand on both the ends of the airplane with yourself near the nose, your friend near the tail. 

-  Your friend yells out something at you, but you can't hear it, because it's Mach 1.

- You ask the pilot to slow down the plane, and the plane gradually decelerates. 
What happens now?

- Your friend's sound catches up with you, and you hear the message!

- Now, you yell out something at your friend.

- You speed up the plane, and your friend catches up with the message. 

- Now, something remarkable happens when you do this. 
Your friend hears the message in reverse!!

- Now the most interesting part:

If you keep on accelerating and decelerating the plane about the speed of sound, ***you can make your message to be heard multiple times by your friend!!***

Isn't it wonderful? Hearing the *same message* again and again without any effort from your part! 

***It is weird, but is such an observation plausible?*** 

UPDATE: Most of the comments posted here are about the rewinding part. In fact, that is only a part of the question. The real question emphasizes on the idea, of receiving a signal by overtaking it. The energy loss due to the sound propagation can be easily solved by using a hollow straight tube, between the friends.

  [1]: https://i.sstatic.net/qJDt1.jpg