In Greek myth, Echo was a beautiful young maiden. But she angered one of the gods by talking too much, and was ordered never to speak again, except to repeat the last words that she had heard.
Then Echo fell in love with a youth named Narcissus. When he failed to return her love, she grew sad and eventually pined away, until only her voice was left.
According to the Greek tale, it’s the voice of Echo that you hear, repeating your words, whenever you hear an echo!