This International Standard defines a reference sound source and specifies procedures for characterizing and calibrating such sources. It requires that the reference sound source be calibrated while operating on a reflecting plane and radiating sound into z free field above that plane. In addition, this International Standard specifies procedures for further characteriza-tion of reference sound sources in a fully anechoic environment and in a reverberant environment. It describes installation and operating conditions for the reference sound source under test and specifies the type of microphone calibration as well as the microphone positions to be utilized in calibrating and characterizing the reference sound source in conformity with the general requirements of ISO 3741 and ISO 3745. Calibration data are to be obtained at both octave and one-third octave band levels as well as A-weighted levels.