A BETTER HEARING AID MODELED ON A FLY'S EAR

More than 31 million Americans are hearing-impaired, and approximately seven million use hearing aids. But, while hearing aids can work wonders, they can’t do one important thing that human ears do at every waking moment: concentrate on what a person wants to hear and filter out the background noise. That’s why, even with the help of a hearing aid, a hearing-impaired person may have difficulty following a conversation in a crowded room.

Now, for people who need a more sophisticated hearing aid, help is on the way and it’s coming from a most unusual place—the lowly fly. Here’s how: The reproductive cycle of the parasitic night-fly, the Ormia ochracea, demands that it lays its eggs on or near live crickets. As for the cricket, it chirps to attract a mate. So the Ormia has evolved with specialized equipment to home in on its cricket host by hearing its chirps and sensing where the sounds are coming from. Unlike other animals, the fly’s tiny eardrums are connected to each other, and they respond to sound waves by moving in different directions, allowing the fly’s brain to determine where the sound is coming from.

The night fly’s tiny but sensitive ears were noticed by two researchers at universities in upstate New York: Ronald Hoy, a professor in the Neurobiology and Behavior department at Cornell University, and Ronald Miles, chairman of the Mechanical Engineering Department at the State University of New York at Binghamton. Working together, they’re designing a hearing aid with small microphone diaphragms that will detect sounds and locate their sources in much the same way that a night-fly’s ear works. Once these hearing aids are available, hearing-impaired people will be better able to distinguish sounds in noisy places.

Their research is being funded by the National Institutes for Health, the National Institute on Deafness and Other Communications Disorders and the Defense Applied Research Projects Agency.

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