You Can Thank This Fly for Advances in Hearing Aid Technology

By David Brown & Chinlin PanJuly 23, 2014 2:57 pm|

Imagine being in a room full of people – a cacophony of conversations and noise. Despite standing right next to someone, you strain to hear her voice.

People who use hearing aids often struggle to focus on one voice – especially in noisy environments. They could crank up the volume on their hearing aids – but that would also crank up the volume of everything else in the background.

Professor Neal Hall and his group of graduate students from the Cockrell School of Engineering at the University of Texas offers a solution: a device that mimics the hearing powers of a fly.

What’s so special about this fly? The Ormia ochracea can accurately locate a chirping cricket with its acute hearing, determining a sound’s direction within two degrees. According to Hall, researchers who discovered this were flabbergasted: no one expected a small insect to have that kind of hearing, due to the close distance between its ears for the sound waves.

The Texas Standard’s David Brown spoke with Hall about the hearing device. “Unlike humans, the fly’s ears are coupled by something that resembles a teeter totter … growing up in east Texas, we call them seesaws,” Hall says.

At two millimeters wide and made out of silicon, people can use this device as a hearing aid to distinguish a voice in a room, because the device’s seesaw-like mechanism is directional to sound.

“If the sound arrives from the top of the seesaw, it hits the left and the right sides at precisely the same instant and there’s no net pressure difference to drive the seesaw into motion,” Hall says. “Whereas if sound was coming from the left or right side, then because of the finite speed of sound travel, it hits one side just a split second before the other and the pressure difference sets that [seesaw] into motion. So basically, if you point the seesaw mechanism at a speaker of interest, it will hear that speaker very effectively, while at the same time, not responding at all to noises originating at the side.”

Although Hall and his team just finished creating a prototype, the device could be ready for mass production in a couple of years. In the meantime, work on the device continues.