Explanation
Echoes are produced by the reflection of sound waves. When a sound wave encounters a reflecting surface such as a wall, cliff, or mountain, it bounces back towards the source. If the reflected sound wave reaches the listener's ear after a time delay of more than 0.1 second, it is perceived as a distinct sound called an echo.
The quality of the echo depends on the distance between the source and the reflecting surface, as well as the nature of the reflecting surface. Smooth, hard surfaces such as walls, rocks, and buildings reflect sound waves better than soft and irregular surfaces such as grass, trees, and hills.
Echoes are used in a variety of applications, including sonar, radar, and medical imaging. By measuring the time delay between the transmitted signal and the received echo, information about the location, distance, and shape of objects can be obtained.
