Have you ever called out "Hello" only to have your own voice answer you back a moment later with your very same "Hello"?? An echo can seem very mysterious and strange what causes it to happen?
If you've ever touched the top of a stereo speaker and felt it vibrating, then you've already felt the way sound moves and travels. Sound is actually little moving vibrations sent through the air that translate into noises when our ears pick them up.
An echo is what happens when these little moving vibrations bounce off a surface as they travel and play back again a second time. (Or even a third, fourth, and more!) That's why an echo is more likely to happen when the sound has a lot of surfaces to bounce off of. Now you know why caves and alleyways are usually so full of echoes! (...full of echoes...full of echoes...full of echoes!)
by Mya Kagan (Whyzz writer)