The Uncertainty of the Proposed Single Number Ratings for Airborne Sound Insulation

A replacement of the ISO 717-1 standard for the calculation of the single number ratings for airborne sound insulation has been proposed. The proposed replacement, ISO 16717-1 introduces new single number ratings for airborne sound insulation. The weighted sound reduction index which has traditionally been calculated from the sound reduction index measured in the 1/3 octave bands from 100 Hz to 3150 Hz will be replaced by a new single number rating Rliving which is calculated from the 1/3 octave bands between 50 Hz and 5000 Hz. The uncertainty of the proposed single number ratings has been estimated using the ISO Guide to the Expression of Uncertainty in Measurement (GUM) and validated using Monte Carlo simulations. The uncertainty of the single number ratings of 200 building elements was evaluated. It was found that the uncertainty of the single number ratings is highly dependent on the shape of the sound reduction index curve. The uncertainty of the new single number rating Rliving was found to be greater than the uncertainty of the traditional weighted sound reduction index for 98% of the 200 lightweight building elements included in the evaluation. It is recommended that the current weighted sound reduction index be maintained in the replacement standard until the uncertainty of the calculation of the sound reduction index at the low frequencies can be reduced through a redefinition of the measurand.