Methods for the characterization of sound packages containing visco-elastic and anisotropic porous materials

Abstract

International audienceA wide range of commercial applications, in both building acoustics as well as automotive industry, can be found for sound packages containing poro-elastic materials. Accurate material characterization is vital for the use of these multilayered systems due to the increasing demands in acoustic comfort and legislation. There is however a distressing lack in raw, accurate material data and measurement methods concerning the characterization of these materials. Especially the effect of anisotropy and visco-elasticity on the acoustic properties of multilayered systems remains barely understood. Measuring and modeling methods for the characterization of these materials at an acoustically interesting frequency range will be presented. The experimental technique for the determination of the elastic properties is based upon the excitation of waveguides in anisotropic and visco-elastic porous materials. The other parameters of the Biot-Allard model are determined using the classical methods. Results concerning surface wave phase velocities show that anisotropy and visco-elasticity influence the acoustical properties of porous media which are calculated using a transfer matrix approach