Batch Substitution Calibration of a Mems Microphone Array : Impact of Sensor Performance Dispersion on Directivity Estimation

With their small size, embedded analog-to-digital converter, and low cost, MEMS microphones are good candidates when deploying arrays dedicated to 3 dimensional high resolution directivity measurements. Measuring the sensitivity and phase uncertainties across the sensors of such an array can help quantifying their impact on the performance of the array.In this work, a batch substitution calibration procedure is proposed. It is used to calibrate an array compounded of 128 sub-arrays of 8 MEMS microphones. This allows to estimate the dispersion in sensitivity on the frequency range 100– 2000Hz, and higher bounds for the dispersions of the sensitivity and phase on the frequency range 100–5000Hz. An analysis of the obtained sensitivity statistics at 1kHz corroborates the results of a recent study. Eventually, Monte-Carlo simulations are run in order to assess the impact of the measured sensor sensitivity and phase dispersion levels when estimating sound source directivities.