This International Standard specifies two laboratory methods for determining the sound power level of a source. It gives requirements for the test room, as well as the source location, operating conditions and instrumentation. Techniques are specified for obtaining an estimate of the sorface sound pressure level from which the weighted sound power level of the source as well as the sound power level in octave or one-third octave bands may be calculated. It is intended to prescribe techniques for acoustical measurements that may be used in test codes for particular types of equipment.