A self-reciprocity calibration of spherical transducers using boundary reflection in a spherical shell.

A self-reciprocity method is described for calibrating a spherical transducer in a spherical shell. The reciprocity constant is calculated using Green's function and the electroacoustic reciprocal principle in the spherical shell. A sensitivity correction is developed by calculating the transducer's receiving force in different fields. An experimental measurement setup is described to calibrate transducers with diameters of 20 and 30 mm in the frequency range from 25 to 63 kHz, calibrated in a 500 mm diameter spherical shell with a thickness of 2 mm. The largest discrepancy in calibration results between the self-reciprocity and three-transducer spherical-wave reciprocity method is around -1.4 dB. The self-reciprocity calibration method, with a smaller volume required than the three-transducer spherical-wave reciprocity method, has a potential advantage in calibrating the transducer at high hydrostatic pressure and varying water temperatures.