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What is an echo?
When you say something, air from your lungs vibrates your vocal cords, and what comes out of your mouth are just moving air vibrations. If you are speaking to someone, these vibrations keep moving forward until they get to a personís ear and are "heard".
If the vibrations (which are often called "sound waves") hit some object like a wall, then they will tend to bounce off the wall just like a ball would. Now if this wall is a long way away, the sound wave will take a little while to get to the wall and a little while to get back. When we hear it again, it can sometimes be a few seconds later because of the distance that the sound traveled. Thatís where an echo comes from. Itís just the sound of something nearby that we heard once but part of it went a long way and got bounced back so we hear it again.
(republished on 07/29/06)
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