Ultra-Broadband Sound Absorbing Materials Based on Periodic Gradient Impedance Matching

Ultra-broadband sound absorption with periodic gradient impedance matching is of great concern in the research acoustic materials. This study investigates composite metamaterials comprising micro-perforated plates (MPPs) and subsequent Fabry–Pérot(FP) channels. Based on theory, ultra-broadband has been realized through a design 36 channels whose thickness only 50 mm. Also, average coefficient 88% an frequency bandwidth (490–4000 Hz) can be achieved by preserving impedance. Furthermore, changing perfect absorber being 100 mm, reach greater than 90% range 250–4500 Hz. The proposed structure validated analytically experimentally. work help designing improving method metasurfaces especially have potential designs.