DIN EN ISO 3746:2011

Acoustics - Determination of sound power levels and sound energy levels of noise sources using sound pressure - Survey method using an enveloping measurement surface over a reflecting plane (ISO 3746:2010); German version EN ISO 3746:2010

This Standard specifies methods determining the sound power level or sound energy level of a noise source from sound pressure levels measured on a surface enveloping a noise source (machinery or equipment) in a test environment for which requirements are given. The sound power level (or, in the case of noise bursts or transient noise emission, the sound energy level) produced by the noise source with frequency-weighting A applied is calculated using those measurements. The methods specified in this Standard are suitable for all types of noise (steady, non-steady, fluctuating, isolated bursts of sound energy, etc.) definedin DIN EN ISO 12001. This Standard is applicable to all types and sizes of noise source (e. g. stationary or slowly moving plant, installation, machine, component or sub-assembly), provided the conditions for the measurements can be met. The test environments that are applicable for measurements made in accordance with this Standard can be located indoors or outdoors, with one or more sound-reflecting planes present on or near which the noise source under test is mounted. Information is given on the uncertainty of the sound power levels and sound energy levels determined in accordance with this Standard, for measurements made with frequency weighting A applied. The uncertainty conforms with that of accuracy grade 3 according to DIN EN ISO 12001.*This standard describes methods of accuracy grade 3 (survey grade) for determining the sound power level and sound energy level of a noise source (machinery or equipment) from sound pressure levels measured on a surface enveloping a noise source. For this purpose, the noise source shall be mounted on one - and in front of more, if relevant - sound-reflecting surface(s). Requirements are specified, amongst other things, for the test environment, instrumentation, measurement surfaces and installation and operation of the noise source under test. The annexes describe methods for the determination of the environmental correction and for microphone arrays on the various measurement surfaces. Another annex contains a guideline on the development of information on measurement uncertainty. The most important alterations with respect to the 2009 edition of the standard are as follows: a) determination of sound energy levels has been added; b) treatment of measurement uncertainty has been extended and approach in accordance with the GUM Guide has been added; c) annex on qualification procedures for the acoustic environment has been reduced to a simple method (estimation method) for the determination of the environmental correction; d)specifications about microphone arrays on a quarter hemispherical measurement surface (position of the noise source in a corner) have been added; e) annex on the detection of impulsive noise has been deleted; f) annex with a guideline on the development of information on measurement uncertainty has been added; g) standard has been completely editorially revised. The international standard on which this standard is based has been prepared by Working Group 28 "Basic machinery noise emission standards" of ISO/TC 43/SC 1 "Noise" with German participation. On the European level, the standard exists within the framework of CEN/TC 211 "Acoustics". Regarding German cooperation, the responsible Working Committee is NA 001-01-04 AA "Geräuschemission von Maschinen und Anlagen; Messung, Minderung, Datensammlung" ("Noise emission of machines and plants: measurement, reduction, data collection") of NALS.