Introduction of bats Wave and Ultrasound Ultrasound used by bats
Bats are the only mammal that can fly. The structure of bat’s body is different from bird structure of body. Bats are divided into two groups; micro bats and mega bats. Bats are nocturnal animal; they are active at night. Most bats cannot see at night. Therefore, they use echolocation producing ultrasound, which allows bats to be active at night. Bats hunt small insects such as flies and they avoid obstacles by using ultrasound. Bats are distributed all around the world except for north pole and south pole.
Wave is a disturbance that travels through material and accompanied by a transfer of energy. The movement of ultrasound travels through a medium such as air. Ultrasound is a cyclic sound pressure wave with a frequency, which is greater than human hearing. Bats can make 50~90 KHz (a unit of frequency) and hear the sound reflected that they made. Frequency of bat’s ultrasound is directive; It is not absorbed even into the water. This enables bats to be active at night and catch insects in darkness.
It is used for fish finder, echo-sounder and for the medical. An oscillator using piezoelectric effect of crystal flake produces ultrasound.
Bats use echolocation, biological frequency, in order to make ultrasound. When bats emit ultrasound from their mouth, they can hear high frequency that they make while flying; they listen to the vibration that return from various objects near them.
Bats use ultrasound for navigation. They catch flying insects in darkness while flying in full speed. Their sophisticated echolocation permits them to distinguish between a moth and a falling leaf.