Precision method for phase match of microphones

This paper describes a precision method for phase match of microphones. The coupler method consists of an acoustical driver that excites two test microphones simultaneously in a small cavity. The phase response contribution of the associated preamplifiers and amplifiers is eliminated with an interchange procedure, which enables the relative phase of a pair of microphones to be assessed accurately. The uncertainty of the method is dependent upon the uncertainty of the phase meter or phase measuring system. Over a frequency range from 63 Hz to 2 kHz and with a commercial phase meter that has an uncertainty of ±0.02 deg, the uncertainty of this coupler method for phase comparison is approximately ±0.05 deg. The coupler is useful over a frequency range from 10 Hz to 6.3 kHz.