A Semi-analytical model for rooms with absorptive boundary conditions

The prediction of sound-fields in closed volumes with vibrating delimiting surfaces typically is carried out by the use of energy methods. Those methods are robust for subsystems with high modal density. However their performance is limited if the spatial resolution of the response has to be described and if boundary conditions are investigated in detail. In order to gain spatial information about the sound pressure in such a volume, the coupled system of fluid (acoustic volume) and structure (boundary conditions) has to be considered in the frequency range of interest. First the components are calculated decoupled. A modal approach is used for the fluid, where analytical results are available for simple geometries. For an efficient numerical implementation, especially for analyzing more complex geometries, spectral approaches are considered in addition to FEM. The boundary conditions are modeled with the help of impedances. The angle of inclination of the incoming waves is considered by a wavenumber dependent description. Plate resonators and arbitrary plate-like compound absorbers are treated using the Theory of Porous Media for modeling porous foam structures and the Lamé Equation for homogeneous materials. The coupling of fluid and structure is carried out with the help of the component mode synthesis.     «

The prediction of sound-fields in closed volumes with vibrating delimiting surfaces typically is carried out by the use of energy methods. Those methods are robust for subsystems with high modal density. However their performance is limited if the spatial resolution of the response has to be described and if boundary conditions are investigated in detail. In order to gain spatial information about the sound pressure in such a volume, the coupled system of fluid (acoustic volume) and structure (b...     »