Question

Q.4) What is an echo?​

Answer 1

Answer:

a sound or sounds caused by the reflection of sound waves from a surface back to the listener.

"the walls threw back the echoes of his footsteps"

Answer 2

Echo means the reflection of sounds it happens because of the sound waves the sound waves bounce back

We can here echos in mountains , caves and canyons

The sound waves bounce back mainly in hard surfaces

The minimum distance to here an echo is 17 meter