Separation of Resonant and Non-Resonant Components—Part I: Sound Reduction Index

Abstract

There is much interest in applying EN12354-1 to lightweight buildings elements which may have critical frequencies above the frequency range of interest. The standard requires that only the resonant component of the sound reduction index be used in the predictions and therefore a reliable method of calculating the resonant component is needed for these elements. Several methods of calculating the resonant component are examined in this study. It was found that the various predictions of the resonant component can differ by as much as 18 dB. Calculation of the resonant component by subtracting the theoretical non-resonant component from the measured value was unreliable due to measurement uncertainty. Calculation of the resonant component using correction factors based on the components of the mean square velocity may be possible but may also be susceptible to measurement uncertainty. Definitive guidance for calculating the resonant component is needed in future revisions of EN12354-1 if it is to be applied to lightweight constructions.