DIN EN ISO 6926:2016-08

Reference sound sources are used extensively in comparison methods to determine the sound emission of fixed sound sources. A reference sound source with known sound power is used to establish a numerical relation between the sound power level of a source at a specific location in a given acoustic environment and the spatially and temporally averaged sound pressure level at a number of microphone positions. Reference sound sources are useful not only for determining the sound power level by the comparison method but may also be used for qualification tests of acoustic environments and for estimating the influence of the acoustic environment on the sound pressure level of one or more sound sources in that environment. This standard defines the essential physical and performance characteristics of reference sound sources and establishes procedures for their calibration not only in the free field above a reflecting plane but also in reverberation test rooms at different distances from the boundary surfaces. It also lays down procedures for providing data for level calibration and for determining the uncertainty of a sound source. This standard differs from DIN EN ISO 6926:2001-12 as follows: a) the clause on measurement uncertainty has been updated with stricter reference to ISO/IEC Guide 98-3 and moved backwards in the standard to be more in line with ISO 3745; b) the corrections for meteorological conditions have been brought in line with ISO 3745:2012; c) a new Annex A on the acoustic radiation impedance correction has been introduced; d) an alternative method using sound intensity for low frequency calibration in hemi-anechoic rooms not fully qualified for low frequencies has been introduced in a new Annex B. This standard includes the German version of European Standard EN ISO 6926:2015. The International Standard ISO 6926:2015, on which this European Standard is based, has been prepared by Technical Committee 43 "Acoustics", Subcommittee SC 1 "Noise" of ISO (secretariat DIN) with German participation. This standard has been prepared by Joint Committee NA 001-01-03 GA (NALS/DKE A 3) "Schallmessgeräte" ("Sound measuring instruments") under NALS chairmanship. Regarding the German collaboration the responsible committee is Joint Committee NA 001-01-03 GA (NALS/DKE A 3) "Schallmessgeräte" ("Sound measuring instruments") under the chairmanship of NALS in collaboration with the Committee NA 001-01-04 AA (NALS A 4) "Geräuschemission von Maschinen und Anlagen; Messung, Minderung, Datensammlung" ("Noise Emission of Machines and Equipment; Measurement, Reduction, Data Collection").