The mid-frequency range acoustic response between 400-1000 Hz has gained particular interest in the automotive industry recently. Simulation of this region is challenging due to the non-negligible statistical effects, especially when acoustic trim is applied. In order to be able to investigate the effect of these materials in the presence of an air cavity, this paper describes the design methodology behind the design and manufacturing of two test apparatuses that include an air cavity. The apparatuses were designed to serve as a validation tool for Finite Element Method (FEM) and Statistical Energy Analysis (SEA) simulations, which meant that an optimal size had to be found based on the number of fluid modes in the cavity. Two types of plate-cavity apparatuses have been designed: one with "rigid walls" and one with "soft walls". In the "rigid wall" cavity, the walls are made out of concrete since these boundary conditions can be perfectly represented in simulations. In the "soft wall" cavity, the walls are made of steel plates and this allows validation of coupling loss simulations between multiple structural subsystems as well as an air cavity. Details of the joining methods, geometries, material selections are elaborated to fully describe the theoretical and practical implications of the designs.
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