Question: Do we hear sound because it echos?

Sarah-Jane Walsh answered on 25 Jun 2013:

Not so much because it echos, but because its is made from vibrations which vibrate our ear drum. Inside our ear we have lots of tiny hairs that detect these vibrations and transmit them to our brain which works out the sound and pitch depending on the frequency and wavelength.

Echos are produced because we hear the sound from the original source but then the sound waves hit an object such as a wall, changes direction and bounces back to us kind of like a reflection, because of a delay in the speed of sound we hear it slightly after the original and as an echo