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The transmission of low frequency noise (LFN) through a structural element is explored by coupling the finite element method (FEM) with the boundary element formulation (BEM). The techniques of component mode synthesis are applied to adjust the stiffness matrix in the FEM formulation. The effect of the elastic boundary conditions on the transmission of sound through a rectangular window is then investigated numerically. Parametric studies have been carried out to examine the effects of natural frequencies, fluid loading and dimensions of the elastic structures on the transmission of LFN. The coupled FEM/BEM formulation is particularly useful to study the structural responses due to LFN below 200 Hz because relevant parametric studies can be conducted numerically avoiding the need of performing tedious and expensive experimental measurements. It has been demonstrated in the numerical simulations that the effects of fluid loading and elastic mounting conditions are particularly important for computing the transmission of airborne excitations through elastic windows with frequency below 125 Hz. [ABSTRACT FROM AUTHOR]