Abstract:

In this paper, a more general sound absorption model for double layered nonwovens is proposed firstly by using the theory of C. Zwikker and C. W. Kosten for sound propagation through porous flexible media and sound propagation boundary conditions, and then a model simulation is detailed by changing the effective structure parameters of nonwovens. Double layered nonwovens composed of polyester fiber in the outer layer and nylon fiber in the inner layer is investigated in detail and the effects of acoustic parameters including the thickness and porosity of each layer on the absorption coefficient are analysed by numerical calculation, respectively. It shows that a double layered sound absorbing structure made of nonwovens has excellent sound absorption and can afford a sufficiently satisfying sound absorption level in a cared frequency range. In theory, this model can be used to calculate the absorption coefficients of double layered nonwovens composed of two different nonwoven materials . In practice, the sound absorption model for double layered nonwovens provides theoretical support for high performance sound absorber design and manufacture.