Abstract:Sound absorption performance of composite structure of perforated closed-cell aluminum foam covered with by soft acoustic cloth backing on its surface was measured according to different cavity thickness. The results show that after perforated closed-cell aluminum foam is covered soft acoustic cloth, its sound absorption coefficient is improved and the highest absorption coefficient is 0.98. High frequency sound absorption coefficient rises obviously and main absorption band is broadened. Sound absorption coefficient peak migrates to low frequency with increase of depth of cavity, which is similar to that of perforated closed-cell aluminum foam bare board.