1.1 General This International Standard specifies a direct method and a comparis n method for determining the sound power level produced by a source. It specifies conditions concerning the test room, the location of the source and its operating conditions, the equipment and the measurement methods, to obtain an estimate of the root mean square sound pressure, from which the sound pressure is calculated. acoustic power level of the source by octave or third octave band. 1.2 Scope 1.2.1 Types of nois This International Standard is applicable primarily to sources producing stable, broadband nois as defined in is 2204. NOTE — When there are dis rete frequencies or narrow bands of nois in the spectrum of a source, the root mean square pressure tends to depend strongly on the positions of the source and the microphone in the room. The average value over a limited microphone path or for a series of microphones may differ significantly from the value averaged over all points in the room. Methods for determining the sound power radiated by a source when there are dis rete sounds in the spectrum are specified in is 3742. 1.2.2 Dimensions of the source This International Standard is applicable to small nois sources, i.e. that is to say, sources having a volume, preferably less than 1% of the volume of the reverberation room used for the test. 1.3 Uncertainty in measurements The measurements carried out in accordance with this International Standard result in standard deviations less than or equal to those indicated in table 2. The standard deviation takes into account the cumulative effects of all the causes of uncertainty.
NBN S 01-201-1979 history
1979NBN S 01-201-1979 Acoustics - Determination of sound power levels of noise sources -Precision raethods for broad-band sources in reverberation rooms