Acoustic Simulation of Multilayered Noise Control Treatment with Porous Material

Porous materials have been applied increasingly for absorbing noise energy and improving the acoustic performance. Different models have been proposed to predict the performance of these materials, and much progress has been achieved. However, most of the foregoing researches have been conducted on a single layer of porous material. In real application, porous materials are usually combined with other kinds of materials to compose a multilayered noise control treatment. This paper investigates the acoustic performance of such treatments with a combination of porous and non-porous media. Results from numerical simulation are compared to experimental measurements. Transfer matrix method is adopted to simulate the insertion loss and absorption associated with three samples of a noise control treatment product, which has two porous layers bonded by an impervious screen. The elastic parameters of the solid phase of a foam or fiber mat are estimated by matching the simulated results to the tested data. It is concluded that appropriately considering the elasticity of the frame in the porous materials is the key to correctly simulate the acoustic performance of multilayer treatments, especially if the global stiffness of the treatment combined with its mass create a local resonance.