Predicting acoustic transmission loss through laminated glass with air and porous layers

This study analyses the sound transmission characteristic of various laminated glass designs with application to motor vehicles. The porous interlayer in the laminated glass is filled with polyvinyl butyral (PVB) that serves as an acoustic damper. To model the physics behind the sound transmission losses of the fluid, solid and porous layers, acoustic noise transfer matrices are used to relate the dynamic characteristics of two interlayer points in the laminated glass. The porous model includes the effect of the variation in porosity on Poisson's ratio involving the wave number as well as the bulk modulus. Furthermore, an interface matrix is introduced, which defines the dynamic interaction at the interface of every layer. The addition of a fluid layer, like air, yields an interesting phenomenon of two coincidence dips. Finally, a set of parametric studies are performed to observe the transmission loss characteristic due to changes in glass thickness and porous layer.