Evaluation of Precision and Accuracy in the Calibration of Hydrophones

The Underwater Sound Reference Division has made a preliminary study of the accuracy or bias measurement of hydrophone sensitivity by the comparison method and of the precision or repeatability of the measurements. To evaluate the various calibration systems, two standard hydrophones were calibrated a number of times by reciprocity with a minimum of electronic equipment. The averages from the repetitions were taken as 'true' values of hydrophone sensitivity. Three sets of calibration data then were obtained for both hydrophones with each calibration system, and the results were compared with the 'true' values to obtain estimates of the bias and confidence interval associated with each system.