An echo is a sound which reflects because of the sound waves and comes back to the ears of listener also say it reflects. because the distance is very short nd the voice reflects so fast hat we cant be aware of it.

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Since sound travels at a fixed speed (about 340 meters per second), it takes a wall and it bounce back to you. when you make a sound , you'll here the sound waves the first time( when the sound travels from your vocal chords to you