Pressure Coupling Chamber for Comparison Calibration of Hydrophones at Frequencies from a Few Hz Up to 1-2 kHz

This paper presents a novel pressure coupling chamber for calibrating hydrophones in the frequency range from a few Hz to 1-2 kHz. The design uses an array of loudspeakers and a microphone as projectors and a reference sensor, respectively, acoustically coupled through a medium inside the chamber. The projectors are mounted on the chamber walls around the hydrophone's sensitive element to create a homogeneous acoustic field. The chamber's acoustic length is nearly half that of existing designs, significantly extending the high-frequency calibration range. The paper outlines the calibration setup and procedure, validating the new design through comparisons of B&K 8104 and B&K 8106 hydrophone calibrations. The results are consistent with data from the international project "Underwater Acoustic Calibration Standards for Frequencies Below 1 kHz" (15RPT02 UNAC-LOW), supported by EURAMET.