Analysis of the aspects affecting sound radiation efficiency based on numerical simulations

The sound radiation efficiency of a vibrating structure is an acoustic descriptor, used both to compare and optimise products, and as input data in prediction models based on statistical energy analysis. Although a published standard for the measurements of the radiation efficiency is not yet available, the proposal ISO/CD 10848-5, regarding laboratory measurement methods to characterise the acoustic radiation of a building element, is currently under evaluation. The radiation efficiency of certain elements clearly depends on their dimension, on the type of excitation, the boundary conditions and the orientation of the baffles surrounding the sample. Moreover, evidence from different studies suggests that several factors related to the test arrangement strongly influence the results. These include the positions over which the vibration response of the tested element is measured, and, when the diffuse sound field approach is used to evaluate the radiated sound power, the number and the arrangement of the positions over which sound pressure levels are measured. The aim of this study is to analyse those aspects which strongly affect the experimental evaluation of the radiation efficiency, based on numerical simulations. To this purpose a homogeneous concrete wall was investigated by means of an FE vibro-acoustic analysis.