There is a great interest in computational models describing the behaviour of coupled acoustic-structural systems. A finite element programme for acoustics has been developed incorporating a variety of elements including porous material elements described by the Blot-theory and plate elements described by thick plate theory (Reissner-Mindlin). This paper makes up a part of an experimental verification of models incorporating these plate and porous material elements, models which may be used for the prediction of airborne and impact sound transmission in multilayer systems, of which sandwich constructions are an important type. Forced response measurements have been performed on sandwich beams, a 50mm thick polyurethane foam core sandwiched between two aluminium plates, 2-3 mm thick. The measured input and transfer mobility data as well as plate vibrational shape have been compared with both 2- and 3-dimensional models of the beam. Due to the complexity of the model description, in particular the porous material, a rather simple SD-model was used. However, the fit between measured and calculated data was quite satisfactory indicating that a 3-dimensional model is necessary for better precision particularly in frequency ranges where dilatational motion, or antiphase motion of the skins, is important.