The Ormia ochracea fly's exceptional sense of hearing has inspired researchers to develop technology that could be used to create sophisticated hearing aids.
These flies have a keen ability to hear the chirping of crickets, which they spread their larvae on so the young can eat the insect from the inside-out, the American Institute of Physics (AIP) reported. The fly's ultra-accurate sense of hearing is believed to be thanks to a "sophisticated sound processing system."
A University of Austin Texas team developed a small prototype that mimics the parasitic fly's hearing mechanism. The findings were described in a recent edition of the journal Applied Physics Letters. The device is two millimeters wide and uses piezoelectric materials to turn mechanical strain into electrical materials. This allows the prototype to operate using very little power.
"Synthesizing the special mechanism with piezoelectric readout is a big step forward towards commercialization of the technology," said Neal Hall, an assistant professor in the Cockrell School of Engineering at UT Austin. "Minimizing power consumption is always an important consideration in hearing-aid device technology."
The device could also have applications in the military, such as in dark environments where visual cues are not available.
Humans can pinpoint sound sources because the speed of the noise combined with the separation between our ears. The difference in time it takes for the sound waves to hit our ears allows the brain to process it perceptually. Insects tend to lack this ability because they are so small sounds hit both sides simultaneously; O. ochracea is an exception to this rule. The fly can locate the direction of the cricket's chirp even though its ears are less than two millimeters apart; this is due to a structure that resembles a "teeter-totter" about 1.5 mm long. In the four millionths of a second between when the sound goes in one ear and then the other, the sound phase shifts.
Researchers created a "pressure-sensitive teeter-totter." Using piezoelectric materials allowed the team to simultaneously measure how the beam flexed and rotated; this helped them replicate the fly's unique ability. The technology could lead to hearing aids containing intelligent microphones that adaptively focus on sounds the wearer is most interested in. The product will require further testing and development before it can be applied to the real world.
"The delicate mechanism must be protected from consumer handling with surrounding packaging," Hall said, "something the fly need not worry too much about."
