The closed-coupler reciprocity calibration of probe microphones

Although the closed-coupler reciprocity method of pressure calibration of probe microphones offers, in principle, considerable practical advantages over the current method of using a Rayleigh disk in a resonant tube it is shown that only by careful choice of size of coupler can accurate calibrations by the reciprocity method be achieved, and even these calibrations are restricted to the frequency range below about 1 kc/s.