Optical directional binaural acoustic sensor via an asymmetric mechanical model

Abstract

High-resolution sound source localization (SSL) with a short baseline could be accomplished using a coupled diaphragm. However, the symmetric coupled diaphragm is limited by the resonance characteristic and is not conducive to locating targets that are not of natural frequency. To achieve miniaturization of directional acoustic sensors for broadband applications, we propose an optical directional acoustic sensor with an asymmetric coupled diaphragm. An improved mechanical model of the asymmetric coupled diaphragm is established, and the directional response pattern around the natural frequency of the rocking mode is simulated. According to the frequency response experiment, we ensure rocking and bending modes at 2820 Hz and 2890 Hz, respectively. The directional performance from 2800 Hz to 2900 Hz is estimated for all azimuth angles. We experimentally verify that the interaural differences are amplified by a maximum factor of 3.4 over a wide bandwidth of 102 Hz. The results indicate that a broader interaural differences amplification is achieved by the binaural acoustic sensor via an asymmetric mechanical model compared to the previous symmetric model.