In this paper a method is presented for modeling sound fields in acoustic volumes with vibrating delimiting surfaces. The model is based on a Component Mode Synthesis, where the fluid-component is considered by its normal modes and constraint modes at the interface, which could result from e.g. Finite or Spectral Element calculations. Compound absorbers consisting of homogeneous plates and porous layers are coupled with the fluid as boundary conditions. Their differential equations are solved in the wavenumber-frequency-domain after applying a Fourier Transform. Wavenumber and frequency- dependent impedances are computed for these infinite structures and used for the coupling. Finally Hamilton´s Principle is formulated for the coupled system and the steady state response is calculated for a harmonically oscillating pressure load. The application of this method is presented for a simple 2D model of a rectangular room with a compound absorber, consisting of a porous foam between two layers of homogeneous material, applied as an impedance boundary condition at one surface.     «

In this paper a method is presented for modeling sound fields in acoustic volumes with vibrating delimiting surfaces. The model is based on a Component Mode Synthesis, where the fluid-component is considered by its normal modes and constraint modes at the interface, which could result from e.g. Finite or Spectral Element calculations. Compound absorbers consisting of homogeneous plates and porous layers are coupled with the fluid as boundary conditions. Their differential equations are solved i...     »