To help them find their prey in the dark, most species of bats have indeed developed a navigation system called echolocation. Bats make sounds the same way that we humans do, by moving air past their vibrating vocal chords. These winged creatures have been known to emit sounds from their mouths which they hold open as they fly, or through their nose.
How Echolocation Works
Echolocation is extremely high pitched and beyond human hearing range. However, the sound behaves the same way as the sound of a human shouting. It travels through air as a sound wave and the energy of that wave then bounces off of whatever objects it comes across. Bats emit these sound waves and then listen very carefully to the echoes that return to them. A bat’s brain processes the returning information and uses it to figure out how far away a certain object is, along with how big the object is, and what direction it is moving in.
Processing Information
Bats are also able to tell if an insect is to the right or left. They do this by comparing when the sound reaches its right ear to when it reaches the left ear. If the sound of the echo reaches the right ear before it reaches the left, then the insect is to the right and vice versa. Bats have very complex ears. They are able to determine an insect’s vertical position and can even tell if an insect is edible or not.
Bats are able to tell the size of an insect based on the intensity of an echo. A smaller object reflects less of a sound wave and therefore produces a less intense echo as well. The bat can sense in which direction the insect is moving based on the pitch of the echo. For instance, if the insect is moving away from the bat, the returning echo will have a lower pitch than the original sound, while the echo from an insect moving toward the bat will have a higher pitch. This difference is due to something known as the Doppler effect.
Last but not least, contrary to what many believe, most bats have pretty good vision. They use echolocation alongside their vision, not instead of it.
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