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 noise sources inside a building and
traffic outside a building;
c) gives rules for determining these quantities from the results
of measurements carried out in one- third-octave or octave bands in
accordance with ISO 10140-2, ISO 140-4, and ISO 140-5. The
single-number quantities in accordance with this part of ISO 717
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 0,1 dB 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 ISO 10140,
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 with in Annex B.