DIN EN ISO 3745:2017-10

This standard specifies procedures of accuracy class 1 for determining the sound power and sound energy levels of noise sources. For this purpose, the noise source (machinery or equipment) under test is mounted either in a free-field test room or hemi-free-field test room (anechoic room or hemi-anechoic room) and sound pressure levels (in one-third octave bands or with frequency weighting A) and measured on a measurement surface enveloping the noise source. The calculated sound power levels and sound energy levels include corrections to allow for any differences that might exist between the meteorological conditions under which the tests are conducted and reference meteorological conditions. In general, the frequency range of interest includes the one-third-octave bands with mid-band frequencies from 100 Hz to 10 000 Hz. The range can be extended or restricted to frequencies beyond or within these limits, to those between which the test room is qualified for the purposes of these measurements. The specified methods are suitable for all types of noise (steady, non-steady, fluctuating) according to DIN EN ISO 12001. The noise source under test can be a device, machine, component or sub-assembly. The maximum size of the noise source depends on specified requirements regarding the radius of the hypothetical sphere or hemisphere used as the enveloping measurement surface. The test rooms that are applicable for measurements made in accordance with this standard are an anechoic room or hemi-anechoic room, also called, respectively, a free-field test room or hemi-free-field test room. Information and further details are given on the uncertainty of the sound power levels and sound energy levels determined in accordance with this standard. The most significant change compared to the 2012 standard is the complete revision of Annex A "General procedures for qualification of anechoic and hemi-anechoic rooms". This now refers to ISO 26101 "Acoustics - Test methods for the qualification of free-field environments" and specifies how ISO 26101 is to be applied within the scope of DIN EN ISO 3745. The International Standard has been prepared by Working Group 28 "Basic machinery noise emission standards" of ISO/TC 43/SC 1 "Noise" (secretariat: DIN) with German collaboration. At the European level the standard falls within the scope of CEN/TC 211 "Acoustics" (secretariat: DIN). Regarding the German collaboration, 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") at DIN/VDI Standards Committee Acoustics, Noise Control and Vibration Engineering (NALS).