Prediction of the sound reduction index: a modal approach

Different methods for the calculation of the sound reduction index using modal analysis are described. The calculations use two steps: a vibratory study to determine the transverse displacement of the plate and a study of radiation. Orthotropic plates are studied in particular and the resulting calculation algorithm has been programmed. Initial hypotheses are indicated, as well as results obtained for various plates or partitions. Modal analysis calculation results are then compared to results of the Cremer–Sewell approach.