Dr. Neal A. Hall received a bachelor’s degree in mechanical engineering from the Cockrell School of Engineering at The University of Texas at Austin in 1999, and his M.S. and Ph.D. degrees in mechanical engineering from the Georgia Institute of Technology, in 2002 and 2004, respectively. From 2004 to 2006, he was an Intelligence Community Post-Doctoral Fellow with Sandia National Laboratories, in Albuquerque, New Mexico. He joined the Department of Electrical and Computer Engineering at UT Austin where he performs research in the areas of silicon micromachined acoustic transducers. He was a recipient of the DARPA Young Faculty Award in 2012 and the ONR Young Investigator Award in 2014.
Fly Inspired Hearing
About 40 years ago, scientists working in at a field lab in Austin, Texas discovered that a predatory fly known as the Ormia ochracea is able to locate crickets by listening for the male cricket’s mating song.
How the directional microphone works.
The fact that the fly is able to precisely locate the cricket using its song is so remarkable that it has inspired researchers to develop technologies that imitate the fly’s hearing. Recently, we created the first hearing device that is identical in size and function to this special fly’s hearing organ, which is vastly superior to humans
People can crudely determine the location of a sound source by taking advantage of the small difference in arrival time of sound waves between our left and right ears. The fly’s ears are only 1.5mm apart, and these differences are just 4 millionths of a second. What the fly accomplishes is in some ways equivalent to a person experiencing an earthquake in California, and using their two feet to determine that the epicenter of the quake was in Chile.
A team of researchers discovered that the fly accomplishes this task using a hearing organ that resembles a microscopic teeter-totter, similar to what you’d find in a children’s playground. Sound waves travel through the air and hit one side of the teeter-totter just slightly before the other side, setting it into a rocking motion. The mechanism “hears” only in preferred directions, along the axis of the teeter-totter.
Four decades after the fly’s super hearing power was first discovered, we aim to apply these mimics to develop hearing-aids that can pinpoint a speaker of interest in a noisy restaurant, while filtering out background noise that degrades speech and can be painful to the eardrums. We believe this technology could also be useful on the battlefield where it can be used to find the location of hidden snipers.
Micrograph of the fly-inspired microphone.
The difference of sound waveforms from the fly-inspired microphone vs. conventional microphone.
Actual recordings at anechoic chamber (fly-inspired microphone [i.e. directional microphone]
Actual recordings at anechoic chamber (fly-inspired microphone [i.e. conventional microphone]