The Acoustic Behaviors of Dual Layered Nonwoven Absorbers: From Model Building to Experiment Verification

Abstract

Nonwovens are ideal materials for use as noise control elements because of their unique physical structure and special acoustic behaviors, especially when their structures are complicatedly designed. In this paper, we first deduce a sound absorption model for dual-layered porous nonwovens by extending the Zwikker and Kosten theory. Then a theoretical analysis and a numerical simulation of the impact of thickness and porosity of outer and inner layers on the sound absorption coefficient are followed by an experiment designed to compare the calculated sound absorption coefficients and the measured ones. Experiment results indicate that the measured and the calculated sound absorption coefficients are very similar in trend with change of thickness, porosity and sound frequency, apart from the obvious difference at low frequency. Finally, the main reasons for the differences between the theoretic data and the experimental ones are also explored.