Sound transmission through a thin baffled plate: validation of a light fluid approximation with numerical and experimental results.

The response of a thin elastic rectangular baffled plate embedded in a gas and excited by an incident acoustic field is studied theoretically and experimentally. The model equations are analyzed by a perturbation method based on the expansion of the solution in eigenmodes and a small parameter. The small parameter expresses that the gas has a density which is small with respect to the density of the plate. The approximation obtained, the so-called light fluid approximation, is compared with the numerical solution of the exact boundary integral equations equivalent to the initial system of partial differential equations. Finally, the predictions given by the light fluid approximation are compared with experimental results. These two comparisons show the efficiency and the accuracy of the method.