Scientists recently released a new hearing device with mechanics and design inspired by Ormia ochracea, a parasitic fly that uses extremely quiet sounds to locate crickets. The fly's hearing mechanism is remarkably small for being able to hear that noise, 50 times smaller than the wavelength of sound emitted by the cricket, according to the report published in Applied Physics Letters.
Neal Hall, an assistant professor of electrical and computer engineering at the University of Texas, said, "The thing that makes it very special is that the fly ear is so small." The abstract of the paper said that, "The hearing mechanism is, for all practical purposes, a point in space with no significant interaural time or level differences to draw from."
The fly's ear has a hearing mechanism that uses multiple vibration modes to amplify interaural time and level differences. The team has designed a prototype of a microphone inspired by the fly's ear. The microphone replicates the sound localization ability of the fly. The prototype is made of silicon microchips and uses multiple piezoelectric sensing ports to simultaneously convert the vibration into a physical quantity, which allows simultaneous measurement of sound pressure and pressure gradient.
The fly ormia ochracea is a parasite which uses its super-refined hearing to locate crickets, and lay eggs on their backs. These larvae burrow into the cricket when they hatch and then eat the cricket alive.
Although ormia ochracea is a fly in the ointment to crickets, lessons that scientists have learned from studying its ears could be a boon to people suffering from hearing loss.
Humans have a time lag between when we hear something in one ear, and when it reaches the other ear. The remarkable thing about these flies is that sound reaches both of their ears at the same exact time. "We have a significant separation between our ears," Hall 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."
The fly's ears are linked by a structure which helps locate the direction of sound. Hall says, "It's like having two microphones in one that are linked together by this teeter-totter."
Since this mechanism was first explained by neurobiologist Ronald Hoy and engineer Ronald Miles in 1995, many people have tried to create a man-made microphone with the same effect.
Hall says that his team's microphone is unique in that it is simpler than others and more energy efficient.