A Russian-Chinese international comparison of hydrophone calibration methods

This is the final report of a Russian-Chinese international comparison of h ydrophone calibration methods conducted by exchanging hydrophones between t he Hangzhou Applied Acoustics Research Institute (HAARI) and the All-Russia n Scientific and Research Institute for Physical-technical and Radio-techni cal Measurements (VNIIFTRI). The comparison was organized in 1997/98 in ord er to assess the current state of the art for hydrophone calibration in the Russian Federation and China. Six hydrophones of different types were cali brated using the Russian and Chinese Underwater Pressure National Standards in the frequency range 1 Hz to 630 kHz. The following methods and faciliti es for hydrophone calibration were used during the comparison: piezoelectri c compensation in a closed chamber, vibrating column in an open chamber, an d free-field reciprocity in the laboratory tanks. Some features and nuances of these facilities are considered. The agreement of 140 calibration data was checked for six hydrophones. The mean and maximum differences between t he participants' results were 0.24 dB and 1.6 dB, respectively.