Corrected version 2026-01


1.1        General


This document specifies methods for determining the sound power level of a noise source from sound pressure levels measured on a surface enveloping the noise source (machinery or equipment) in an environment that approximates to an acoustic free field near one or more reflecting planes. The sound power level produced by the noise source, in frequency bands or with A-weighting applied, is calculated using those measurements.


NOTE   Differently shaped measurement surfaces can yield differing estimates of the sound power level of a given noise source which are accounted for in the uncertainty associated with this test method. An appropriately drafted noise test code (see ISO 12001) gives detailed information on the selection of the surface.


1.2        Types of noise and noise sources


The methods specified in this document are suitable for all types of noise (steady, non-steady, and fluctuating) as defined in ISO 12001, except for short duration, impulsive events.


This document is applicable to all types and sizes of noise source (e.g. stationary or slowly moving component or sub-assembly), provided that the conditions for the measurements can be met.


NOTE   It is possible that the conditions for measurements given in this document are impracticable for very tall or very long sources such as chimneys, ducts, conveyors and multi-source industrial plants. A noise test code for the determination of noise emission of specific sources can provide alternative methods in such cases.


1.3        Test environment


The test environments that are applic...