This paper discussed the sound absorption properties of polyester fabric backed with cavity.In our study

different theory was applied to explain the properties of polyester fabric backed with cavity.The conclusion is that the stand wave in the tube will not change their frequency and phase by the absorption of fabric

the Zwikker and Costen theory can give the absorption law at different frequency roughly

the first maximum sound absorption coefficient frequency can be got by the perforated resonance theory.The capillary sound absorption theory and microperforated resonance theory is not agree with the practice of polyester fabric.