Reseachers see cricket ears as model for better hearing aids

New advances in hearing aids and medical imaging may be possible thanks to a tiny insect from the South American jungle, according to a study released Thursday. The South American bush cricket, also called the katydid, has some of the smallest ears of any creature on the planet. But despite a physical structure that is very different from human ears -- and an entirely different evolutionary history -- katydid ears function in a remarkably similar way to human ears. Mammalian ears use a three-part process -- the eardrum collects the sound, the middle ear converts it from air-born noise into liquid-born vibrations, and a structure called the cochlea analyzes the frequency. It had been well-known that the crickets had eardrum-like apparatuses on their two forelegs. But scientists were unclear as to how these tympana connected with each other and with the sensory receptors to allow the cricket to actually hear. In the new study, published in the November 16 issue of the US journal "Science," researchers reveal the discovery of a microscopic organ that acts as a "middle ear" for the crickets. The cricket version "relies on a system of mechanical levers, a sort of microscopic see-saw formed by its eardrum that makes the link to the inner ear," the researchers explained in a statement. "The ears of this bush cricket are teaching us that complex hearing mechanisms can take place in very small ears. As such we are learning how evolution has come up with very small, efficient and sophisticated microphones," said Daniel Robert of University of Bristol in England, one of the study's lead authors. "We now have to learn how to make one like this," he added. James Windmill, from the Centre for Ultrasonic Engineering in the University of Strathclyde, also in England, explained that the insect mechanisms could perhaps be incorporated into a variety of technologies to help humans, "including hearing aids, biomedical imaging systems for hospitals, and ultrasonic non-destructive evaluation to assess the structural integrity of buildings and bridges." He said he looked forward to "the next stage of this important research, bringing together bioscience and engineering to create the bio-inspired sensors of the future."