| Experimental methods have been developed for measurement and characterization of miniature, micro-fabricated microphone diaphragms. These include omni-directional pressure and pressure differential diaphragms that are not electrically active. An acoustic setup consisting of a laser vibrometer and a calibrated reference microphone is used to estimate the acoustic response of the microphone diaphragms. Equivalent dynamic parameters are estimated by a least squares curve fit of the theoretical governing equation, where the statistical information used in the procedure is estimated from measured spectral density functions. Limitations of this setup are addressed.; Improvements to these procedures have been made. A different laser vibrometer configuration has been developed that facilitates the testing of micro-fabricated diaphragms with capacitive sensing plates, which could not be measured with the previous experimental setup. Another benefit of this setup is the laser vibrometer is removed from the sound field. A modification to the parameter estimation procedure was done that involves the estimation of a time delay associated with the sound field measurement error, giving improved estimations of the dynamic parameters.; In addition to measurement and characterization of the micro-fabricated diaphragms, a feasibility study was done to verify the ability of a microphone array consisting of two orthogonal pressure differential microphones and one omni-directional microphone, co-located and co-planar, to localize in three dimensions. Since the micro-fabricated microphones were not available at the time of this research, an array was fabricated from commercially available hearing aid microphones. The array's direction locating ability was demonstrated by implementing a servo controlled video camera with a real time algorithm that pointed the camera in the direction of incident sound sources. |
