IEC 60565-1:2020 specifies methods and procedures for free-field calibration of hydrophones, as well as individual electroacoustic transducers that can be used as hydrophones (receivers) and/or projectors (source transducers). Two general types of calibration are covered within this document: absolute calibration using the method of three-transducer spherical-wave reciprocity, and relative calibration by comparison with a reference device which has already been the subject of an absolute calibration.

The maximum frequency range of the methods specified in this document is from 200 Hz to 1 MHz. The lowest acoustic frequency of application will depend on a number of factors, and will typically be in the range 200 Hz to 5 kHz depending mainly on the dimensions of the chosen test facility, The highest frequency of application for the methods described here is 1 MHz.