ISO 9295 measurement of high frequency sound power level (16 kHz octave band) from all types of products

摘要

ISO is in the process of revising ISO 9295:1988, which is the only ISO acoustic standardrnthat prescribes conditions for determining sound power levels in the 16 kHz octave band.rnOne of the most significant changes will be to expand the scope to include all types ofrnproducts that emit high frequency sound from the previous scope of only informationrntechnology products, such as display devices, power supplies and disk drives. The newrnscope will include other products which emit high frequency sounds, such as some medicalrndevices and laboratory equipment. Because of several technical factors (includingrndirectivity and significant air absorption), the determination of high frequency soundrnpower levels requires additional precautions from the procedures contained in ISOrnstandards for reverberation rooms and hemi-anechoic rooms. The revision is based on thern5th edition of ECMA-108; the first version of ISO 9295 was based on an earlier version ofrnECMA-108. The revision will include a wider range of air absorption coefficients withrnequations that are aligned to ISO 9613-1. This paper describes in detail the latest version ofrnISO/CD 9295 and presents results from the latest meeting of ISO Technical Committee 43rn(Acoustics) Sub-committee 1 (Noise) Working Group 28.