An echo of recognition
An artificial bat device reveals more about how bats use echolocation to navigate.
Bats produce loud calls and listen to the returning echoes to find their way around. This process, known as echolocation, is sometimes described as ‘seeing with sound’. The way bats perceive the world through echolocation, however, is fundamentally different from how we experience it through vision. Echolocation provides much less information about the world than vision does, but despite this, bats are agile navigators and hunters.
It is not clear how bats navigate so well without much information. In particular, researchers would like to know how echolocating bats recognize the places that they regularly visit while foraging and navigating. When we visually recognize places, we identify and localize the various objects making up the scene. But echolocation is unlikely to provide enough information to allow bats to identify and localize the objects in a particular place.
To investigate how bats recognize places, Dieter Vanderelst and co-workers built an artificial bat: a device that contained ultrasonic microphones to act like the bat’s ears and an ultrasonic speaker to act like the bat’s mouth. The artificial bat device was then used to collect echoes from different locations in real bat habitats.
Processing the echoes using machine-learning techniques showed that the echoes that returned from each location were different enough for a computer to recognize the location. By using a simplified version of the echoes, Vanderelst and co-workers also showed that the locations could be recognized even if there was not enough information to identify specific objects or vegetation at the site. This suggests that bats do not simply use echolocation to recreate the three-dimensional layout of a location, as some researchers have proposed.
While much remains to be learned about how bats use echolocation for navigation, future work that teases out bat navigation strategies might help us to build robots that can navigate using similar tactics.
To find out more
Read the eLife research paper on which this eLife digest is based: “Place recognition using batlike sonar” (August 2, 2016).
