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If you were a cricket, this little fly would make you very nervous. (Courtesy of Louisiana State Arthropod Museum)

How a Tiny Fly's Ears Could Help You Hear Better

by Kara Manke
Jul 22, 2014

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This microphone prototype designed by Neal Hall at the University of Texas is about the size of a fingernail.

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Ormia ochracea is not a very likeable creature, even by fly standards.

This parasitic fly likes to leave its larvae on the backs of crickets. The larvae burrow inside the cricket and then proceed to eat the cricket alive.

But humans who have struggled with hearing loss might soon be thankful for one at least small part of this fly - its ears.

Ormia ochracea has developed very specialized ears that let it locate crickets by following the sound of their chirp. Scientists are using these ears as inspiration in developing microphones for the next generation of directional hearing aids.

"The thing that makes it very special is that the fly ear is so small," says Neal Hall, an assistant professor of electrical and computer engineering at the University of Texas. Hall and his team have developed a prototype of a microphone inspired by the Ormia ochracea ear, which was published Tuesday in Applied Physics Letters.

Humans have large noggins, says Hall, and these big heads of ours to help us figure out which direction a sound is coming from.

"We have a significant separation between our ears," he explains, "so sound arrives at one ear just a split second before the other. Our brain ... looks at those very minute differences in time of arrival to locate the object."

But the fly head is tiny - its ears are separated by only a millimeter, which is about the thickness of the average fingernail - so sound arrives at both ears at almost the exact same time.

To overcome the limits of its itsy-bitsy head, the fly has evolved a special way of hearing: Its two eardrums are connected by a small rigid structure that behaves like a teeter-totter, and this teeter-totter amplifies very small differences in the arrival time of sound.

"It's like having two microphones in one that are linked together by this teeter-totter," says Hall.

The teeter-totter mechanism in the fly ear was first explained by mechanical engineer Ronald Miles and neurobiologist Ronald Hoy in 1995 - NPR's Morning Edition even featured a segment on the discovery way back in 1999.

Since then, a number of scientists have strived to create tiny, man-made microphones that mimic the teeter-totter mechanism in the fly ear. Within the past year, teams lead by Ronald Miles at Binghampton University and Miao Yu at the University of Maryland have also published directional microphone prototypes inspired by the Ormia ochracea.

Hall says that in his microphone, the motion of the teeter-totter is detected using a special type of material that emits an electrical signal when it changes shape. This approach is not as sensitive to direction as some of the other approaches, but it may be simpler and more energy efficient.

"We've made a big leap forward in terms of reducing power consumption and the readiness of the technology to make an impact," he says.

Of course, most people aren't interested in chasing down crickets to feed to their kids for dinner. But these fly-inspired microphones could be applied to a number of more human endeavors - smartphones, defense tracking - or directional hearing aids.

"The number one complaint of hearing aid users is that they cannot hear in noise," says Ruth Bentler, who studies the effectiveness of directional hearing aids at the University of Iowa. "As soon as you have any degree of hearing loss and you walk into a crowded restaurant, it becomes difficult to hear speech."

Bentler says the solution for many is directional hearing aids, which use one or more microphones to cancel out noise coming from the side or from the back of the head. These hearing aids are "designed to be more sensitive to noises coming from the 'look' direction," she says.

"The teetering mechanism has some significant design advantages over how one would normally try to implement a directional hearing system," says Hall. Using a single teeter-totter mechanism could reduce power consumption - which is always an issue in battery-powered hearing aids - and help them maintain calibration over time.

But even though scientists are getting close to replicating the capabilities of Ormia ochracea's ears, Hall says he's still impressed at the capability of this little fly.

"It is the equivalent of if you were just standing on the ground and all of a sudden the ground starts shaking because there was an earthquake, and I told you I can tell just by my feet that the epicenter of the earthquake was in Costa Rica," Hall says. "The fly does something equally remarkable in locating sound given the proximity of its ears."

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If you were a cricket, this little fly would make you very nervous. (Courtesy of Louisiana State Arthropod Museum)

Despite Disability, One Mountain Climber Reflects On His Advantages

Jul 22, 2014 (Tell Me More) — Spencer West was born with a genetic disorder that led to both his legs being amputated. West tells host Michel Martin about how he climbed Mount Kilimanjaro using just his hands and arms.

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A set of three images showing the larger of Mars' two moons, Phobos, passed directly in front of the sun as seen by NASA's Mars rover Curiosity. (NASA/JPL-Caltech)

What's Better Than A Total Eclipse Of The Sun? Check This

Jul 22, 2014

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Solar eclipse or cross-eyed space alien?

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Any eclipse is worth seeing. A total eclipse — where the moon completely blots out the sun, where day turns to night, where solar flares ring the moon's shadow like a crown of flame — that's the eclipse everybody wants to see, the alpha eclipse that eclipses all the other eclipses. Everybody knows this (me included), until I saw this ...

Yes, it looks like a cross-eyed space alien staring out of the darkness, so to make things clearer, let me add one more "eye," like this ...

What are we looking at? On August 20, 2013, NASA's robot Curiosity was sitting on a Martian plain and one of its cameras looked up at the sky and saw the little moon Phobos passing across the face of the sun. Curiosity's camera snapped a picture every three seconds. So what you see here is a sequence. The moon appears on the right side of the sun, moves center, exits left, a passage that took about 37 seconds. Had you been on Mars that day, this (NASA animated its photos) is what you would have seen ...

Obviously, this is not a total eclipse. Phobos, it turns out, is too small to cover the sun. It is, amazingly, only 14 miles wide. Our moon, by comparison, is 2,160 miles across.

So how does this itty bitty moon manage to loom so large against the sun, and how come it's so rock-like, so bumpy around the edges — so utterly gorgeous to watch?

The answer is, Phobos orbits very close to Mars' surface. It's only 3,700 miles up. Our moon, by contrast, is (on average) 239,000 miles away. So, Phobos is sailing very, very near, which is why Curiosity can see it in such detail and why it blots out so much of the sun.

Which Would I Rather See?

If you asked me to choose between a total solar eclipse of our moon, and a chance to catch Phobos voguing in sharp outline while I watch from a Martian plain, I'm going for the Martian option: the Little Guy in Partial Eclipse. Not only is it thrillingly beautiful, it is also, I should mention, a tragedy in motion.

Our moon, the Earth's moon, has been gradually drifting away from us. When the earth was younger, our moon was 10 times closer than it is now. Phobos, on the other hand, isn't moving out, it's moving in — closer and closer and closer to Mars. What's more, it's slowing down.

These days it circles Mars every 8 hours. But in the next 10 to 15 million years or so, Mark Lemmon, of Texas A&M University, told Space.com, Phobos will slow its speed so significantly that, at some point, it will "get so close that tidal forces from Mars will very likely break it up before it does start grazing the atmosphere and come down."

Oh, No ...

What happens then? When a moon disintegrates, it breaks into hundreds of millions of pieces; those pieces splay, then gather, and (at least for a while) they become a ring — like the rings we see around Saturn. When Phobos goes, "Mars may briefly have a ring system," says Lemmon.

'Goodbye,' The Little Moon Is Saying

Which is why, when you see Phobos in partial eclipse on Mars, you are watching a diva making what will one day be its final appearance in our solar system.

So consider what we've got here: a death spiral, a light show, a dying beauty backlit by the sun, What's more fantastic than that? Yes, total eclipses are still nice, still worth traveling to see, but now that I know what Mars gets to see — I'm switching sides. When it comes to eclipses, Partial is the new Total.

At least when I'm on Mars.


Thanks to Marc Kaufman, whose new book, Mars Up Close: Inside the Curiosity Mission, introduced me to some of the images featured here.

Copyright 2014 NPR. To see more, visit http://www.npr.org/.

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'I’m Not Stupid, Just Dyslexic'

Jul 22, 2014 (Here & Now / WBUR-FM)

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Josh Thibeau, 12, is struggling to attain his personal goal: to complete a single Harry Potter book. The sixth grader has been grappling with reading for as long as he can remember. It is not due to lack of smarts or motivation — Josh is dyslexic.

"There was a student that said, 'Are you stupid?' Because my brain was working in a different way," Josh said. "And I'm just like, 'No, I am not stupid...I'm just dyslexic.' "

In every U.S.classroom, on average, one or two students has dyslexia. The brain-based learning disability often runs in families and can make reading painfully difficult.

This week, Here & Nowhas a series of reports called "Brain Matters: Reporting from the Front Lines of Neuroscience" from contributor station WBUR.

Rachel Zimmerman hasthe story of new research that shows it's possible to pick up some of the signs of dyslexia in the brain even before kids learn to read.

The findings may substantially influence how educators, parents, and professionals address the disorder.

Reporter

Copyright 2014 WBUR-FM. To see more, visit http://www.wbur.org.

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Federal Court Throws Out Health Care Subsidies In 36 States

Jul 22, 2014 (Morning Edition / WBUR-FM) — Julie Rovner of Kaiser Health News explains a federal appeals court ruling Tuesday that overturns subsidies provided to low- and middle-income people in states that use the federal health exchanges.

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