August 14, 2020
Microelectromechanical systems (MEMS) based directional sound sensors have been developed to mimic the unique hearing mechanism of the parasitoid fly Ormia ochracea. The fly appears to analyze the superposition of the two natural oscillation modes (rocking and bending) of the coupled eardrums to identify the incident direction of the cricket chirp. This approach allows it to accurately determine the direction of sound using wavelengths that are much longer than the separation of fly's hearing organs. The sensor developed by NPS consists of two wings that are attached to a substrate using two torsional legs at the middle as detailed in several previous theses. The current detection systems based on the fly’s hearing system requires two sensors to uniquely determine the direction since only one mode is utilized. This study focuses on the use of a single MEMS sensor by analyzing the superposition of the rocking and bending modes in order to produce a sensor that directly mimics the parasitoid fly while reducing the overall size of the device. The measurements show that signals from the two wings can be processed to uniquely determine the direction of sound. In addition, the measurements agreed well with that of simulations utilizing finite element modeling. The findings indicate that MEMS based sensors having dimensions much smaller than the wavelength of sound they detect can be developed to accurately determine the bearing of incident sound.
Lieutenant Brian R. Gureck commissioned into the United States Navy as a Nuclear Submarine Officer in May of 2013 from the United States Naval Academy, earning a Bachelor of Science, with distinction, in Honors Systems Engineering. LT Gureck subsequently completed Naval Nuclear Propulsion training, graduating near the top of his class. South Carolina. He served as the Chemistry Radiological Assistant, Ship’s Diving Officer, and Assistant Engineer Officer onboard USS LOUISVILLE (SSN 724), a LOS ANGELES-class nuclear-powered fast attack submarine home-ported in Pearl Harbor, Hawaii. While onboard USS LOUISVILLE, LT Gureck completed two Western Pacific Deployments, conducting several missions vital to national security. In June of 2020, he graduated with distinction from the Naval Postgraduate School with a Master’s Degree in Combat Systems Sciences and Engineering (Applied Physics). LT Gureck’s thesis was titled Resolving Bearing Ambiguity with a Single Bio-Inspired Direction Finding MEMS Acoustic Sensor.