Improvement of the sound absorption performance of polycarbonate automobile window pane using micro-perforated membrane absorbers

Absorption performance of automobile window pane is poor by traditional methods using laminated plate with resin membrane between two folders of pane because of the low acoustic impedance of membrane resonator restricted by pane area. A compact and efficient sound absorbing structure without porous material is designed as a combination of baffle-resonators and Helmholtz-resonators comprising a perforated membrane with sub-millimeter holes backed by an air space. Its performance is predicted by equivalent electric-acoustic circuit analysis. Numerical examples are given. In addition, several important influence factors are discussed affecting on the acoustic absorption performance. The numerical computation results show that absorption performance is feasible more improved by using double layers of micro-perforated membrane and air space structure.