Insect Research May Produce Better Hearing Aids

A diverse group of insects known as katydids possess extremely complicated ear structures -- located on their two front knees -- and can detect sound frequencies that other animals, including humans, cannot. Professor Glenn Morris of zoology, who has been studying katydids for 30 years, believes their auditory systems could serve as a model for smaller, improved human hearing aids and other acoustic devices.

Morris studies the different notes and frequencies produced by the insect. He then tries to relate these to the shape of the katydids' ear. "Although katydids are an extremely diverse insect group, their ears have evolved to listen to sounds made by their own particular species," he says. Male katydids have a diverse range of frequencies while females are usually mute. "Some frequencies are so amazingly high that not only are people unable to hear them but the insects themselves can't either, unless they're practically sitting side by side." These high frequencies may enable the insects to avoid predators such as bats who might eavesdrop on a male as he sings for a mate, he notes.

Morris, who has studied the katydids of Ecuador, Columbia, Costa Rica, Venezuela and Panama, is currently making working models of the insects' ears to see how they function. The Natural Sciences and Engineering Research Council is funding his research.