Question

Define echo.

Answer 1

1. The sound heard after reflection from a rigid surface such as a cliff or a wall is called echo.
2. An echo can be heard if the distance between the source of sound and the reflecting surface is greater than or equal to 17m and the time difference between direct and reflected sound is greater than 0.1s.
3. The echo is used by bats and dolphins to detect obstacles in their way, navigation, etc.