Answer to Question #101733 in Astronomy | Astrophysics for Sara Bourgaize

Question

You are exploring in a cave and call out to one of your friends. You hear your echo. Which interaction of sound caused the echo and how did the sound waves move?

Answer 1

The considered interaction of sound is reflection. The sound wave may reflect from hard surfaces many times and the reflected wave will reach your ears. The waves that you perceive as echo are the waves propagating in the opposite direction with regard to the sound waves that your mouth produce. You produce sounds propagating from your head to the walls of the cave, the echo propagates from the walls to your head.