This work presents a measurement uncertainty evaluation of the free-field sensitivity of a MEMS microphone using a substitution comparison method. The measurement setup is based on principles used in secondary microphone calibration, with sensitivity determined relative to a calibrated reference microphone. The uncertainty analysis follows the Guide to the Expression of Uncertainty in Measurement (GUM), where Type A and Type B uncertainty evaluations are propagated through a defined measurement model to obtain the final measurement result.
The MEMS microphone sensitivity is estimated together with an expanded uncertainty, where the uncertainties associated with the reference microphone are identified as the dominant contributors. Broadband results show that the measured sensitivity is close to the typical manufacturer sensitivity over a wide frequency range and follows a similar frequency trend. The proposed approach enables reproducible estimation of the free-field sensitivity of MEMS microphones and provides a clear framework for uncertainty evaluation.
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