Just around the corner: Acoustic mirroring enables echolocating bats to detect occluded objects

Abstract

The ability to detect salient targets and segregate them from background clutter is a key function of sensory systems. The echolocating bat Eptesicus fuscus is an ideal model for investigating the influence of clutter on target detection, as they must navigate dense foliage at high speed, while tracking moving prey. This difficult task requires bats to reliably detect and track objects in the environment despite changes in distance, angle of view, and interference from background echoes, which obscure targets from sonar “view” and creates barriers bats must navigate around. Counterintuitively, recent studies reveal that environmental clutter echoes may improve performance under some conditions. Neurophysiological recordings in the bat inferior colliculus indicate that acoustic scattering caused by foliage can improve target discrimination when the separation between target and clutter is ∼20 cm. These findings suggest that acoustic reflections from clutter may provide additional “glimpses” of targets and improve target discrimination. Here, we test the ability of echolocating bats to make use of acoustic mirrors from clutter objects for target detection using a yes/no behavioral assay inspired by Non-Line of Sight Imaging experiments. Much like technology employed by machine imaging, robotics, and self-driving automobiles, we test the potential for bats to “see around corners” using only echoes reflected from objects in the environment to locate a target hidden behind an occluder.