This International Standard is applicable to sounders, which are treated as entirely passive electroacoustic transducer elements. Piezoelectric diaphragms, which are the principal components of piezoelectric sounders, are also included. Buzzers which are sound sources with built-in electric circuits are excluded. The object of this standard is to standardize the definitions relating to these electroacoustic transducers, and to list characteristics to be specified and the relevant methods of measurement.