EVS-EN ISO 3747:2009

This International Standard specifies a method for determining the sound power levels of sound sources insitu, especially if non-movable. A comparison method is used and all measurements are carried out in octavebands. The measurement uncertainty depends on the test environment. The measurement uncertainty is evaluatedby comparing with an indicator describing the spatial sound distribution. The accuracy will either be that of anengineering method or a survey method.The sound power level of the source under test is calculated from the measured values of the sound pressurelevels produced at specified measurement points by the source and by a reference sound source, respectively. Thesound power level is calculated using the calibrated values of the reference sound source and the differencesbetween the values obtained with the source under test and those of the reference sound source. All calculationsare carried out in octave bands, from which the A-weighted sound power level is determined.