This International Standard IEC 60500 specifies the relevant characteristics and properties of hydrophones in the frequency range 1 Hz to 500 kHz, and specifies how to report these characteristics. The scope does not cover performance requirements for specific hydrophone types, or for specific hydrophone applications. However, guidance on the choice of a hydrophone with appropriate performance for a specific application is given in an informative annex (Annex A). This standard is applicable to: hydrophones employing piezoelectric sensor elements, designed to respond to sound pressure in water and measure underwater acoustical signals; hydrophones used for measurements of sound pressure in sinusoidal, pulsed (including gated tone burst), or broadband underwater sound fields; hydrophones designed for use in for use in calibration of other hydrophones; hydrophones with or without an integral pre-amplifier.