Uncertainties of measurement and prediction of the sound insulation in a building is an important issue to the building industry, because they put increased expenses on all actors of the building process who have to keep safety margins to prescribed requirements. This report deals with estimates of both types of uncertainty and some recommendations on suitable safety margins are given.
Requirements on sound insulation are described in the Swedish sound classification standards SS 25267 and SS 25268. New standards for the measurement and the prediction (by calculation) of sound insulation have been developed over the last years, and the frequency range of interest has been expanded to include low frequencies (50-100 Hz). This project was initiated to examine how the new methods apply to typical building cases with respect to the new requirements on sound insulation (within the expanded frequency range).
An inter-laboratory comparison (round robin) was made in Mölndal, Sweden with the support from Nordisk InnovationsCenter and the eight laboratories participating. The results of this comparison may be considered as examples of uncertainty that may occur in real consultancy work, but the numbers of experienced operators who delivered results, and the complexity of the calculation examples, prevent an interpretation of the results to reliable estimates of the uncertainty of the calculation method.
Some practical aspects on measurements and calculations of sound insulation are discussed, which may help improve the methods applied. The advice given may help the building industry handle uncertainties in prediction and verification more efficiently. The measurement uncertainty can be reduced to some extent by a careful measurement work and an extended averaging procedure.