Characterizing the sound insulation of a specially orthotropic multi-layered medium

This work explores the sound transmission loss provided by the orthotropic multi-layers to elucidate the sound insulation of FRP (Fiber Reinforced Plastics). Mat is the major material considered in the numerical works. The transfer matrices of a single layer of the orthotropic laminate and the fluid are determined. Further, the boundary conditions on the various interface planes are arranged into matrix form. Combining the transfer matrixes and the boundary conditions and applying the transfer matrix method (TMM) yields the surface impedance and the sound transmission loss. The sound-propagation characteristics are studied. Additionally, the STC (Sound Transmission Class) of FRP and steel are compared and discussed.