Sound Insulation Uncertainty of field measurements

The uncertainty of field measurements of a lightweight wall, a heavy weight floor and a façade with a single glazing window was analysed by a Round Robin Test (RRT), conducted in a fullscale experimental building at ITC-CNR (Construction Technologies Institute of the National Research Council of Italy). Each of the 9 teams involved in the RRT replicates the tests 5 times, for a total of 45 measurements for each sample under test, while the reverberation time is repeated 110 times. Both for airborne sound insulation and reverberation time, the main variations are in the low frequency range. The study is also focused on the single number quantities, which are evaluated in both the narrow and the extended range. In the evaluation of single numbers and their uncertainties, including or excluding the low frequencies leads to very significant differences, except in the case of sound insulation of the façade. The uncertainty results were compared with the relevant standards and with literature results. Thus, because of the high uncertainty of the low frequencies, the measurement procedures at low frequencies have to be more deeply investigated, before including the low frequency range in the on-field measurements.