Dynamics of biosonar systems in Horseshoe bats

摘要

Horseshoe bats have an active ultrasonic sonar system that allows the animals to navigate and hunt prey in structure-rich natural environments. The physical components of this biosonar system contain an unusual dynamics that could play a key role in achieving the animals' superior sensory performance. Horseshoe bat biosonar employs elaborate baffle shapes to diffract the outgoing and incoming ultrasonic wave packets; ultrasound is radiated from nostrils that are surrounded by noseleaves and received by large outer ears. Noseleaves and pinnae can be actuated while ultrasonic diffraction takes place. On the emission side, two noseleaf parts, the anterior leaf and the sella, have been shown to be in motion in synchrony with sound emission. On the reception side, the pinnae have been shown to change their shapes by up to 20% of their total length within similar to 100 milliseconds. Due to these shape changes, diffraction of the incoming and outgoing waves is turned into a dynamic physical process. The dynamics of the diffraction process results in likewise dynamic device characteristics. If this additional dynamic dimension was found to enhance the encoding of sensory information substantially, horseshoe bat biosonar could be a model for the use of dynamic physical processes in sensing technology.