Unequal segment areas and corner positions with the enveloping surface method for sound power determination

The standardised methods for the determination of the sound power level according to the enveloping surface methods require a measurement of the sound pressure or sound intensity level on the enveloping surface. While the subdivision of the enveloping surface into unequal segment areas is correctly standardised for the intensity method (ISO 9614, all parts), the sound pressure methods (e.g. ISO 3744) reveal some fuzziness. The reason is the necessary allocation of partial surfaces to measurement points which are normatively located at corners or edges of the parallelepiped measurement surfaces. This effect is especially important with the proposed local increase of the measurement point density in regions of increased sound radiation. The contribution shows which effects unequal areas have and how a correct surface averaging can be implemented in these cases.