Fly-ear Inspired Miniature Directional Microphones: Modeling and Experimental Study

To address the challenges in developing miniature directional microphones, a novel micro-fabricated directional microphone inspired by the superacute ears of the parasitoid fly Ormia ocharacea is presented in this paper. It consists of two clamped circular silicon diaphragms structurally coupled by an oxide/nitride composite bridge. The separation between the diaphragm centers is 1.25 mm, about the same size as the fly ear. A finite element model is developed to achieve a better understanding of the microphone device and guide the optimal design of the miniature microphones. Using a low coherence fiber optic interferometer detection system, the experiment shows that the directional sensitivity of this device is equivalent to a conventional microphone pair that is 9 times larger. Validating the feasibility to replicate the fly ear in a man-made structure, this work is expected to significantly impact many different fronts that require miniature sensors for sound source localization.