ADOPTED_FROM:EN ISO 717-1:1996 This part of ISO 717 a) defines single-number quantities for airborne sound insulation in buildings and of building elements such as walls, floors, doors and windows; b) takes into consideration the different sound level spectra of various noise sources such as noice sources inside a building and traffic outside a building; and c) gives rules for determining these quantites from the results of measurements carried out in one-third-octave or octave bands in accordance with ISO 140-3, ISO 140-4, ISO 140-5, ISO 140-9 and ISO 140-10. The single-number quantities in accordance with this part of ISO 717 are intended for rating the airborne sound insulation and for simplifying the formulation of acoustical requirements in building codes. The required numerical values of the single-number quantities are based on results of measurements in one-third-octave bands or octave bands. For laboratory measurements made in accordance with ISO 140-3, ISO 140-9 and ISO 140-10, single-number quantites should be calculated using one-third-octave bands only. The rating of results of measurements carried out over an enlarged frequency range is dealt with in annex B.