The voice of beat hull would throw back from seabed ; determine the space between beat hull and take - over echo may measure the deepness of ocean at the location 击拍船体的声音会从海底反射过来，因此测定击拍声和接收回声之间的进间间隔，就能测算出那一位置上的海洋深度。
2.
A few years ago it was found that certain bats emit squeaks and by receiving the echoes they could locate and steer clear of obstacles - - or locate flying insects on which they feed 几年前，人们发现有些蝙蝠会发出尖叫，通过接收回声，它们可以清楚的避开障碍物，并定位她们捕食的昆虫。
