IEC 60565-2:2019 specifies the methods for low frequency pressure calibration of hydrophones at frequencies from 0,01 Hz to several kilohertz depending on calibration method. IEC 60565-2:2019, together with IEC 60565-1, replaces the second edition of IEC 60565 published in 2006. This edition constitutes a technical revision. IEC 60565-2:2019 includes the following significant technical changes with respect to the previous edition. 1) IEC 60565 has been divided into two parts: • Part 1: Procedures for free-field calibration; • Part 2: Procedures for low frequency pressure calibration (this document). 2) A relative calibration method has been added to Clause 8: Calibration by piezoelectric compensation. 3) A relative calibration method has been added to Clause 11: Calibration by vibrating column. 4) Clause 12: Calibration by static pressure transducer, has been added. 5) Annex A: Equivalent circuit of the excitation system for calibration with a vibrating column, has been deleted. 6) Subclauses 9.6, 9.7 and 9.8 have been moved to form a new Annex A: Advanced acoustic coupler calibration methods.