Equivalent Size and Acoustic Center of Measuring Hydrophone

The article considers the problem that arises during the amplitude-phase calibration of hydrophones by the reciprocity method and consists in the violation of the consistency of the hydrophone characteristics specified by the manufacturer. Violation of the indicated consistency of characteristics is due to the need to determine the phase-frequency characteristic when calibrating the hydrophone. The manufacturer sets the dimensions of the hydrophone receiving part and the position of the acoustic center according to the drawing of the receiving part and thereby replaces the acoustic parameters with geometric ones. To restore the consistency of the characteristics, it is proposed to determine the position of the acoustic center and the equivalent size of the hydrophone receiving part from the results of acoustic measurements. It is shown that the displacement of the hydrophone acoustic center relative to its geometric center is a typical phenomenon, and the geometric and acoustically measured dimensions of the active element can differ. To ensure the unity of acoustic measurements, it is proposed to introduce the concept of an equivalent radius and to clarify the concept of the hydrophone acoustic center, as well as to standardize the methods of their experimental determining. The results obtained will be useful in monitoring the phase responses of elements of hydroacoustic antennas for various purposes, ensuring the identity of the phase-frequency characteristics of the vector receivers measuring channels, in solving problems related to restoring the acoustic signal shape by the recorded voltage at the receiver output and other various applications, including marine ecology, medical ultrasound studies, etc.