Predicting sound radiation efficiency and sound transmission loss of orthotropic cross-laminated timber panels

In the last decades, new materials and new technologies which satisfy sustainability and energy efficiency demands have been developed for the building construction market. Lightweight structures are becoming increasingly popular, but it has been shown that they cannot provide satisfactory sound insulation to meet the regulation requirements. Therefore a proper acoustic treatment needs to be specifically designed, considering both airborne and structure-borne sound sources. Cross-laminated timber (CLT) elements, for example, have had great success in the last twenty years, both in Europe and North America. CLT plates, due to their peculiar sub-structure, very often exhibit an orthotropic behavior: they have different stiffness properties along their two principle directions. In this paper two prediction models to evaluate the radiation efficiency, due to mechanical excitation, and the sound transmission loss of an orthotropic CLT plate are presented. The main purpose of these simplified models is to provide efficient tools to acousticians, architects and engineers, which might be helpful during the design process of new buildings, or the retrofitting of existing ones. The models are validated by comparing numerical results with experimental data; moreover their applicability and their limitation are discussed.