How does an echo work?
Sounds waves can bounce off solid objects, just as light waves can bounce off off mirrors. But because sound travels much more slowly than light, it can take several seconds to reach our ears. When it arrives, we hear it as an echo. Bats and dolphins use high-pitched echoes to find their food. Echoes are also used in sonar, a way of detecting submarines and mapping the seabed.

Calling back
If you shout at a wall, the sound will bounce back as an echo. To produce a good echo, the wall needs to be big and at least 25 m (80 ft) away.

Tag :echo