How are bats able to fly in the dark?
Sound waves of frequency higher than 20,000 hertz are not audible to human ears. Those are known as ultrasonics. Let us explain how bats can avoid obstacles while flying in complete darkness. During the flight in complete darkness, a bat produces ultrasound in a series of impulses. The impulses on reflection from the obstacle under observation are received by the animal. The animal interprets the distance of the obstacle from the time interval between the transmission and reception of the impulses. The phase difference between the echoes received by the ears enables the animal to locate the exact position of the obstacle.