Multilayer structures allow obtaining good performance in acoustic insulation to eliminate unwanted noise in the medium and high frequencies in many applications such as building and transport industry. In this paper, the sound transmission of multilayer systems is stu- died using the Transfer Matrix Method (TMM). The studied multi-layered panels include elastic, viscoelastic and porous materials. Several configurations of multilayer systems are studied, and their corresponding transmission loss TL is computed. Also, the effects of po- rous material characteristics are studied to evaluate the impact of each parameter.