LAUSR

Abstract A standard defining a common acoustic classification scheme for dwellings is under development by ISO TC42/SC2/WG29 based on the outcomes of European project COST Action TU0901. The proposal stands on the assumption that in the long term many countries will establish building acoustic requirements using a harmonized set of descriptors, and the hypothesis of an extended low frequency range for airborne sound insulation evaluation is considered. In this scenario most countries will need to estimate the influence on their current airborne sound insulation requirements due to the new descriptor. This can better be evaluated if translation equations between existing and new proposed descriptors can be used. This paper initially evaluates the adequacy of performing such translations based on the geometrical relation between the sound reduction index R and the standardized level difference D nT . This procedure is shown to be acceptable when both descriptors (original and translated) use the same assessment frequency range. For the cases where a different assessment frequency range is considered, a different approach is studied. The paper investigates a statistical method to obtain translation equations between existing and proposed descriptors, based on the analysis of a significant set of in-situ measurements. Several translation equations are proposed, and the effect of the frequency range extension on such translations is studied for two typical building systems such as heavy and lightweight walls. Results show that, although it is possible to propose a single translation equation for each existent descriptor, in some cases the spread around the proposed translation line is significant. It is also observed that the effect of building system is more noticeable if different frequency range descriptors are involved in the translation. This points out the difficulty of obtaining a unique translation equation independent of the building type when the descriptors’ assessment frequency range is not the same. For some existent descriptors, the obtained translation is compared with the theoretical method proposed within the findings of COST TU0901. When considering only lightweight walls or the full data set, there is no good agreement between both methods, but for heavyweight walls they converge. Existing requirements in thirty-two countries have been translated into the proposed descriptor D nT,50  ≈ D nT,w  + C 50 – 3150 using the obtained equations. This provides valuable information and an insight for government and building regulation policy makers when updating their legislation.