Sound Source Localization in 2D Using a Pair of Bio–Inspired MEMS Directional Microphones

Abstract

The majority of fly Ormia ochracea inspired sound source localization (SSL) works are limited to 1D, and therefore SSL in 2D can include a new vision for ambiguous acoustic applications. This article reports on an analytical and experimental work on SSL in 2D using a pair of fly O. ochracea inspired MEMS directional microphones. The reported directional microphones were designed identically in circular shape and operated using piezoelectric sensing in 3-3 transducer mode. In X-Y plane, they were canted in a 90° phase difference, i.e., one microphone was in X-axis and another one was in Y-axis. As a result, their directionality results from the X-axis (cosine) and Y-axis (sine) formulated the tangent dependent 2D SSL in the X-Y plane. The highest accuracy of the SSL in 2D was found to be ±2.92° at bending frequency (11.9 kHz) followed by a ±3.25° accuracy at rocking frequency (6.4 kHz), a ±4.68° accuracy at 1 kHz frequency, and a ±6.91° accuracy at 18 kHz frequency. The subjected frequencies were selected based on the measured inter-aural sensitivity difference (mISD) which showed a proportional impact on the cue of 2D SSL, i.e., the directionality. Besides, the basic acoustic functionalities, such as sensitivity, SNR, and self-noise were found to be 20.86 mV/Pa, 66.4 dB, and 27.6 dB SPL, respectively at 1 kHz frequency and 1 Pa sound pressure. Considering this trend of microphones, the outstanding contribution of this work is the SSL in 2D with higher accuracy using a pair of high performing bio-inspired directional microphones.