Uncertainty determination of in situ airborne sound insulation measurements.

In building acoustics the measurement uncertainty of sound insulation measurements is traditionally either not reported or reported as stated in the corresponding standard ISO 12999–1:2014. Determination and application of measurement uncertainties in building acoustics—Part 1: Sound insulation (former ISO 140-2). An alternative procedure is presented in this paper, aiming at evaluating the need of performing individual uncertainty calculations and the effect of extending the frequency range used to calculate sound insulation single number quantities. A large set of in situ airborne sound insulation measurements is investigated following the ISO Guide to the Expression of Uncertainty in Measurement (GUM) both for DnT 1/3 octave bands values and for single number rating DnTA. Two alternative assessment frequency ranges (50/100–5000 Hz) have been considered. The paper describes a methodology for uncertainty determination to emphasize that it is possible to determine such individual uncertainties following the ISO GUM approach to a certain extent and that each individual measurement needs a corresponding measurement uncertainty calculation. In addition, the results show that if the assessment frequency range is extended below 100 Hz, the uncertainty of the single number quantity is increased