Sound absorption of a new bionic multi-layer absorber

The interest of this article lies in the proposition of using bionic method to develop a new sound absorber. Inspired by the coupling absorption structure of a typical silent flying bird-owl, a bionic multi-layer structure is developed, which is composed of micro-silt plate, porous fibrous material and flexible micro-perforated membrane backed with airspace. The impedance transfer method and finite element simulation method (ACTRAN) are applied to calculate the acoustic performance and analyze the influence of different parameters of each layer on absorption coefficients of this model. The effectiveness of this proposed model is tested based on numerical simulations. The average normal incidence absorption coefficient reaches 0.85 within the frequency range from 200 to 2000 Hz. The significant improvement of absorption coefficients can be mainly due to the Helmholtz effects of micro-silt plate and flexible micro-perforated membrane, and the combination with porous materials lead to even better absorption performance in broadband. (C) 2013 Elsevier Ltd. All rights reserved.