A description, using transfer matrices, is given of the propagation of the three inhomogeneous Biot waves in layered porous media. This is applied to predict the surface impedance of porous layered materials at oblique incidence, and an example is presented.

An elaborate experimental study is c a r r i e d out on the effect of the design of sound transmission r o o m s on the sound transmission loss of a l a m i n a t e d glass panel. Systematic comparisons have b e e n m a d e b e t w e e n the results o b t a i n e d by the sound intensity m e t h o d and the conventional t w o -r o o m m e t h o d . R e s e a r c h has b e e n done to learn the influence of the niche, the r o o m volumes, the loudspeaker and microphone positions, the m e a s u r i n g direction, and the diffusor elements. Also, the influence of field reactivity in the r e c e i v i n g r o o m has b e e n s t u d i e d w i t h the intensity t e c h n i q u e .

A matrix representation of the acoustical properties of porous layers at oblique incidence is used to predict the surface impedance of layered porous materials with impervious screens. The screens can be located inside the material or at the surface. Comparisons between prediction and measurement achieved with a new technique are given.

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