Abstract: A series of multilayer acoustical structures without air layer of back were prepared by perforated plates and composites consisting of chlorinated polyethylene and seven-hole hollow polyester fibers. Sound absorption properties of multilayer acoustical structures were tested by transfer function method using SW230 impedance tubes, the effects of compound layers、compound modes、thickness of composites and porosity of perforation plate on acoustical absorption properties were analysed. The result showed that sound absorption properties of bilayer structures presented acoustical characteristics of porous materials when measuring face was perforation plate,while sound absorption properties of bilayer structures presented acoustical characteristics of film cavity resonance when measuring face was composite in bilayer structures,that acoustic frequency range of multilayer sound-absorbing structures was greatly broadened by the organic combination of sound-absorbing mechanis of porous material and resonance absorption mechanism when the number of perforation plate is up to two. As an acoustical absorption structure, it has potential applications in engineering field.

Key words: perforated plate, CPE∕SHPF composite, composite multilayer sound absorption structure, sound absorption coefficient