Researchers at Brown University have released findings in Science that explain how, amid a flurry of trees, bushes, debris and other bats, a single bat can hone in on a target and remain locked during chase. Bats hunt at night and thus rely on sonar to sound their way through the dark; their eyes are not believed to be of much use.
As scientists learn more, the developments will inform how we can install better navigation systems in vehicles that are sonar-led.
Bats are able to navigate through the clutter due to an ability to discern extremely small differences in a sea of noise. As you may have noticed in any creepy movie, when a bat hunts, it’s constantly chirping—or more exactly, sending out sound waves. Those sound waves return to the bat altered in some way due to the manner in which it reflected off surrounding objects.
A change in amplitude (sound intensity) of less than 1.5 decibels, a difference no human could dream of perceiving, informs the flying hunter what is background and what is target. The researchers make the analogy that it is as if that bat were utilizing two screens: one that simply watches the target, the second that watches the surroundings and avoids them.
Strangely, but perhaps obviously, this is much how our eyes work when we watch a moving object. We know how to focus based on the color patterns our eyes receive, while filtering out the peripherals—yet being aware of them. Bats just appear to do it with sound, instead of light.