Tiny Fly Defies Physics with Ability to Identify Sound Direction

Editor: I'm an engineer by training and career (which explains why I'm such a technogeek ;-) I've had years of math, physics, and engineering classes, including acoustics. One of the principles that was drilled into my head is that physical devices can't determine the directionality of waves whose wavelengths are larger than the device. That law of acoustics is about as fundamental as you can get - and it appears to be wrong, as the following article illustrates.

Now before your eyes glaze over, there's a reason I'm sharing this admittedly technical article with you; it has to do with the development of directional microphones. The limit on the effectiveness of directional microphones is exactly the acoustic law that these little critters seem to ignore. And if this research pans out, it may soon be possible to construct a truly effective directional microphone - one that will pick up sounds coming from a single direction (like the person you want to hear) and suppress all the others. In fact, the first prototypes are being built as you read this!

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From Cornell University
For a picture and a video of the fly in action:
http://www.news.cornell.edu/releases/June04/NIH_fly_ear.hrs.html

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Not lost in translation: NIH picks Cornell 'fly ear' study as prime example of translational research in report to HHS Secretary Tommy Thompson
FOR RELEASE: June 9, 2004
Contact: Roger Segelken
Office: 607-255-9736
E-Mail: hrs2@cornell.edu

BETHESDA, Md. -- Oh, to be a fly on the wall at this meeting: Health and Human Services Secretary Tommy Thompson, in his tour yesterday (June 8, 2004) of National Institutes of Health (NIH) headquarters, heard about the NIH's prime example of taxpayer-funded translational research -- development of a new kind of hearing aid that was inspired by basic biological studies of a tiny fly's ear.

The fly is Ormia ochracea, a parasitic insect that needs exceptionally precise directional hearing in order to locate singing crickets. Cornell Professor of Neurobiology and Behavior Ronald R. Hoy, an internationally recognized expert in bioacoustics, had focused on Ormia because it seemed to be doing the impossible: determining the source of sound waves that are wider than the distance between the fly's ears. Humans and some other animals can hear in stereo because their ears are farther apart than sound waves are wide. Thanks to our big heads, we can tell without looking that a cricket is chirping on the left. Small insects -- with the exception of Ormia -- cannot, and Hoy discovered the unique mechanism that lets the fly defy the laws of physics.

Now, in cooperation with Binghamton University nanotechnologist Ronald Miles, Hoy is working on a directional hearing aid that should be smaller, simpler and cost thousands of dollars less than currently available devices. To Lynn E. Luethke, program director for hearing research at the National Institute on Deafness and Other Communication Disorders (NIDOC), that sounded like the federal government's definition of translational research, taking basic-science discoveries to the applied and clinical levels.

NIDOC Program Director Luethke proposed the Cornell-Binghamton study to NIH administrators as one of six suggested examples of translational research for HSS Secretary Thompson, whose department oversees NIH. She was surprised when the Ormia study was the only example chosen, telling Hoy: "Your fly has become the poster child for basic research here at NIH." Thompson was told, among other things, what a fly running on a Ping-Pong ball treadmill has to do with the next generation of nanofabricated hearing aids. (http://www.news.cornell.edu/releases/March01/fly_ear.hrs.html)

Cornell's Hoy credits his Binghamton engineering colleague with a key role in the translation. "Otherwise, the fly might be just an obscure curiosity (but one with lots of neat science)," he said.