Predicting the acoustical radiation of finite size multi-layered structures by applying spatial windowing on infinite structures

A new technique based on a spatial windowing of plane waves is presented in order to take into account the finite size of a plane structure in sound radiation and sound transmission calculation. This technique leads to predicted results which are much closer to experimental measurements than the classical wave approach applied to an infinite structure. In the first part, the principle of the technique is described as well as the derivation of the modified sound radiation efficiency. In the second part, some predicted results, including the sound transmission index of an aluminium plate, a double glazing panel and a multi-layer panel, and the radiation efficiency of a mechanically excited metal plate, are presented and compared to experimental results in order to validate the spatial windowing technique. The effect of the structure size on both sound transmission (acoustical excitation) and sound radiation (mechanical excitation) is also discussed. (C) 2001 Academic Press.