Comparing Simulation and Theory for Scattering Matrix

Acoustic coatings are the most widely used techniques for attenuating sound levels in duct systems. Porous materials are preferred because their performance is less frequency dependent. One of the methods used to describe the acoustic propagation and scattering in ducts containing these porous coatings is the scattering matrix method. The scattering matrix allows to describe the acoustic properties of such a material. This matrix presents a powerful tool for the characterization of duct systems containing porous material because it presents important detailed information on the transmission, reflection, and attenuation phenomena at a duct element. Several works were aimed at calculating the scattering matrix. Others have dealt with some experimental means to measure it. In this paper, A comparison is made between the simulation of an experimental procedure for calculating the diffusion matrix and the transfer matrix method (TMM). Good agreement was found between experiment and theory.