Tunable Sonic Crystals Assisted Sound Absorber with a Single and Multi Local Defect

In this paper, we emphasize on the experimental study of absorption properties of tunable sonic crystal assisted sound absorber regarding replacement of sonic crystal unit with an artificial single and multi local defect element. Nine pieces of Helmholtz resonators was constructed in a three row to form square 3x3 resonators unit sound absorber model. The influence of a single and multiple Helmholtz resonator manipulation on its sound absorption coefficient was investigated. The experimental results show that the artificial defect manipulation gives the promising possibility for researchers to develop tunable sonic crystals assisted sound absorber. The sound absorber shows a higher sound absorption performance on several different frequency bands associated with the local defect placement position in the sonic crystal structure.