A low-noise bio-inspired piezoelectric MEMS directional microphone for noise monitoring

Monitoring and identifying the unwanted sound sources can be an option to control the unwanted noise. According to WHO, about 5% people of this world are having hearing disabilities, and one of the biggest reasons is the inter-layer unwanted noise from apartments and houses. To monitor, the literature is abundant with various approaches, however, the majority of them are reported using microphone array, and most importantly, their internal noise is higher than human-hearing threshold, i.e., 32 dBA/25 dBSPL. As a result, the literature leaves a constraint of monitoring low-noise. Here, we present an optimized fly Ormia ochracea's ears-inspired piezoelectric MEMS directional microphone with bare minimum self-noise. The optimization was carried out in terms of sensor dimensions, sensing and processing circuitry. Accordingly, the developed device showed 25.52 dBSPL self-noise at 1 kHz frequency. The A-weighted noise was measured relative to the angular rotation of sound under audio frequency, and found 19.91 dBA, and 21.61 dBA, respectively for 0°, and 45° of incidence of sound. The produced results are the lowest ever reported by a similar device in the literature. With this lowest noise-in addition to its directionality, the developed device can be extended for simultaneous noise monitoring and source localization.