A design of an acoustic coupler for calibration of hydrophones at low frequencies

The purpose of this article is to present a coupler developed for the calibration of hydrophones at low frequencies in the Central Office of Measures (GUM). Due to the growing demand for marine environment research in the field of underwater noise, implemented in accordance with Directive 2008/56/EC, many models of autonomous underwater noise recorders have been developed. Ensuring the reliability of recorded data begins with the reliable calibration of hydrophones and/or the entire recorder. The choice of the calibration method was made on the basis of a detailed and broad analysis of calibration methods and similar solutions of coupling constructs worldwide. The analysis mainly took into account the documents of the last few years. On the basis of this analysis, the vibrating water column method was chosen and the construction of the coupler was developed. Regular calibration of hydrophones will contribute to reliable underwater noise monitoring in the Baltic region