DIN EN ISO 9295:2015-09

Some machinery and equipment emit high-frequency noise which might be broad-band noise (for example, paper noise of high-speed printing) or narrow-band noise and discrete tones (for example, noise of switching power supplies and video display units or medical devices). This standard specifies four methods for the determination of the sound power levels of high-frequency noise emitted by machinery and equipment in the frequency range covered by the octave band centred at 16 kHz, which includes frequencies between 11,2 kHz and 22,4 kHz. They are complementary to the methods described in ISO 3741 and ISO 3744. The first three methods are based on the reverberation test room technique. The fourth method makes use of a free field over a reflecting plane. The most important changes compared to the predecessor standard DIN EN 29295 of 1991 are as follows: a) the scope has been extended to include all machinery and equipment; b) reference to ISO 7779 has been replaced by reference to ISO 3741 and ISO 3744; c) requirements and recommended meteorological conditions have been merged; d) symbols and designations have been brought in line with the revised basic standards ISO 3741 and ISO 3744; e) calculated sound power levels have been converted to reference meteorological conditions; f) the calculation of A-weighted sound power levels has been deleted; g) Clause 11 "Measurement uncertainty" has been added; h) the former Annex A on coaxial circular paths for microphone traverses has been deleted; i) the calculation of the air absorption coefficient has been corrected; j) the standard has been 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 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").