A self‐reciprocity free‐field response calibration of a resonant electroacoustic transducer may be determined in a small water‐filled tank by only two electrical impedance measurements at each discrete frequency point. The use of a pulse technique permits the measurement of electrical impedance under two conditions: (1) in a free field and (2) under the influence of a totally reflected signal. The vector difference between these two impedances together with the reciprocity parameter (J) establish the free‐field response. No measurement of voltage, current, or power is required; the ratio of the hydrophone voltage to the projector current is measured as an impedance vector. This method is particularly applicable in the ultrasonic frequency range.