Nanoscale ’tsunami’ helps locusts tune in

The remarkable mechanism by which the tiny ears of locusts can hear and distinguish between different tones has been discovered by researchers from the University of Bristol. Understanding how the nanoscale features of the insect eardrum mechanically process sound could open up practical possibilities for the fabrication of embedded signal processing in extremely small microphones. Unlike a microphone membrane, the eardrum of the locust is a complicated structure which is used to process the information contained in an incoming sound. In order to survive, the locust needs to be able to distinguish between the friendly sounds of fellow locusts in its swarm and the sounds of a hunting bat approaching. These sounds differ in their tonal composition: locust sounds are raspy and noisy while bat echolocation calls have distinctly higher frequencies. Using a set of laser beams shining on the locust, Dr Rob Malkin of Bristol's School of Biological Sciences and colleagues were able to observe the effects of incoming sound waves on the eardrum. They found that the locust eardrum behaved in a most unusual way, quite unlike a microphone membrane or the eardrums of other animals.