This part of ISO717 : defines single-number quantities for airborne sound insulation in buildings and of building elements such as walls, floors, doors, and windows; takes into consideration the different sound level spectra of various noise sources such as noise sources inside a building and traffic outside a building; gives rules for determining these quantities from the results of measurements carried out in one-third-octave or octave bands in accordance with ISO10140‑2 , ISO140‑4 , and ISO140‑5 . The single-number quantities in accordance with this part of ISO717 are intended for rating airborne sound insulation and for simplifying the formulation of acoustical requirements in building codes. An additional single-number evaluation in steps of 0,1dB is indicated for the expression of uncertainty (except for spectrum adaptation terms). The required numerical values of the single-number quantities are specified according to varying needs. 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 ISO10140 , single-number quantities should be calculated using one-third-octave bands only. The rating of results of measurements carried out over an enlarged frequency range is dealt within AnnexB .