Miniature directional microphones are desirable and attractive in many applications including micro air vehicles, hearing aid devices, and anti-sniper systems. To overcome the size constraint, the natural world can serve as a source of inspiration. One striking example is found in the parasitoid fly Ormia Ochracea. Although the interaural distance of the fly ears is only 520μm, it can localize its cricket host with a resolution of as small as 2° [1]. The key to this remarkable directional hearing capability has been linked to a mechanical coupling between the fly’s two eardrums [1–3]. By mimicking the fly-ear design, two-membrane devices have been developed in our previous work [4] which can localize sound in one dimension. This work is intended to develop a three-membrane sound localization sensor, with a coupling beam connected between each of the two adjacent membranes. By utilizing the responses from all three membranes, this device can pinpoint a sound source based on the obtained bearing and elevation angles. A reduced-order model with three degrees of freedom has been developed, and parametric studies have been carried out to study the performance of the system. In experiment, the membrane responses have been detected by using a fiber optic interferometric system. The experimental results have demonstrated an improved directional sensitivity compared with that obtained from a conventional microphone array with uncoupled membranes. This work offers an entirely new approach for sensor design and development practice via the seamless integration of bio-inspired solutions, mechanics modeling, micro-fabrication techniques, and optical detection strategies.

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