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

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.