Question

Write the conditions necessary for an echo to occur.

Answer 1

1. The repetition of sound which is reflected from a distant obstacle like walls of a room, mountain, etc is called an echo.
2. The conditions necessary for an echo to be heard are:

2.1. The minimum distance between the source of sound and the reflecting surface should be 17.2 m.

2.2. The time interval between the original sound and the reflected sound to reach the listener should be greater than 0.1 s.