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 expe rimentally. 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 re spect to the density of the plate. The approximation obtained, the so-calle d light fluid approximation, is compared with the numerical solution of the exact boundary integral equations equivalent to the initial system of part ial differential equations. Finally, the predictions given by the light flu id approximation are compared with experimental results. These two comparis ons show the efficiency and the accuracy of the method. (C) 2000 Academic P ress.