scope:

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 surface 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. This International Standard applies to sources which produce sound that is uniformly distributed in frequency over the frequency range of interest and is relatively steady for at least 30 s. The spectrum of the sound may also include prominent discrete-frequency components or narrow bands of noise. The procedures specified in this International Standard may also be applied to sources that emit non-steady noise as defined in ISO 2204, with the exception of an isolated burst of sound energy, or a burst train with a repetition rate less than 10 per second. (See annex I for guidelines on the detection of impulsive noise.) This International Standard applies primarily to small sound sources, i.e. sources whose volumes are preferably less than 0,5 % of the volume of the test room used for the measurements. This restriction is necessary to ensure that the hypothetical sphere or hemisphere surrounding the sources lies in the far radiation field of the source