![]() ![]() The cosine-dependent directionality can be used to localize the incoming sound since it provides maximum and minimum lobes relative to the sound source position 9, 19, 25. The absence of the backplate brings two additional advantages: as almost zero SFD and cosine-dependent directionality 29, 30. To overcome this problem, in recent studies 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, the presence of the backplate was less explored. Nevertheless, the presence of a backplate was a design constraint that limited mechanical vibrations. reported an innovative way to control the SFD and achieve critical damping without further tuning and optimizations 16, 17, 18. ![]() However, controlling squeezed film damping (SFD) was the main challenge in the SMD model. 13 by utilizing the SMD model reported by Miles et al. ochracea ear-inspired MEMS directional microphone, operating in optical sensing, was reported by Gibbons et al. These fundamental advantages of fly-mimicking directional microphones have received significant attention in realizing various acoustic applications. In addition to the improved directional sensitivity, this fly-mimicking directional microphone (DM) minimizes internal noise to 17.9 dBA at a reduced size 12. ochracea, the directional sensitivity can be reduced to a factor of 20log 10(UC d/1.5) (see Fig. For instance, if the conventional directional coupler interdistance is reduced to the ear coupling distance of the fly O. Additionally, the variation of the interdistance results in a negative impact of the directionality. In the stereo configuration, two omnidirectional microphones (OM1 and OM2) need to be placed in an interdistance (UC d) match with the applied sound wavelength, as shown in Fig. The applicability of their SMD model was extended by the same group, where they reported a comparative study between their SMD model and a conventional directional coupler in a stereo configuration 10. At critical damping, they reported that the tympanum close to the incoming sound source produces a phase difference with respect to the farthest tympanum as a result, the acting force, the area of each tympanum multiplied by the applied sound pressure, remains the same for both tympana, but the phase difference affects both IID and ITD 5. reported a spring mass damper (SMD) model of this fly where each individual ear was quantified with mass and supported by a flexible beam 5. Looking at the scope within this area combined with the presented results, this work provides a clear understanding of sound source localization in three dimensions. The resolution at the azimuth plane is found to be ☑.28°, and the same array shows a ± 4.28° resolution when sound is varied from the elevation plane. Both results are found to be compliant, and the angular resolution of sound source localization in three dimensions is found to be ☒° at the normal axis. The whole array is first analytically simulated and then experimentally measured in an anechoic chamber. ![]() In addition, the cosine-dependent horizontal component of the applied sound gives cues for Z-axis directional sensing. In the array, biomimetic MEMS directional microphones are positioned in a 120° angular rotation as a result, six diaphragms out of three directional microphones keep a normal-axis relative to the sound source at six different angles in the azimuth plane starting from 0° to 360° in intervals of ☓0°. This paper focuses on a mm-sized array of three Ormia ochracea ear-inspired piezoelectric MEMS directional microphones, where their in-plane directionality is considered a cue to demonstrate sound source localization in three dimensions. Fly Ormia ochracea ears have been well-studied and mimicked to achieve subwavelength directional sensing, but their efficacy in sound source localization in three dimensions, utilizing sound from the X-, Y-, and Z-axes, has been less explored. ![]()
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