An improved formulation for predicting low-frequency noise transmitted through double-pane windows.

Abstract

With superior sound insulation properties over a single-panel configuration, a double-panel structure with the presence of a cavity has found a wide range of applications for sound insulation. A classical method for combining a finite element method (FEM) with a boundary element method (BEM) is used to examine the transmission of low-frequency noise through double-pane windows in the present study. The technique of component mode synthesis is applied to adjust the stiffness matrix in the FEM formulation in order to examine the effects of elastic boundary conditions on the sound transmission through these structures. However, the Green function for predicting sound propagation in a rectangular long enclosure is used in favor of the free-field Green function for predicting the pressure inside the cavity of the window panes. The predicted pressure in the cavity is then coupled with the FEM formulation for the window panes and the BEM formulations for the sound fields at the outer surfaces of window panes. A parametric study is conducted systematically to allow a detailed examination for the characteristics of sound insulation of a double-pane window at different frequency bands especially for the low-frequency components.