Optimization design and experimental verification of composite absorber with broadband and high efficiency sound absorption

The average sound absorption coefficient of a composite absorber from 0 to 1.6 kHz was maximized using a teaching–learning-based optimization algorithm, where the geometric parameters were used as optimization variables. The effective-medium model and transfer-matrix method were used to calculate the sound absorption coefficient, and optimized sound absorption coefficient was maximized at 0.938. The specific acoustic impedance of the material is almost perfectly matched with air thanks to the optimized size of the lateral plates, micro-perforated plates, and cavities. Experimental results confirm the theoretical calculation, showing the investigated passive acoustic design method of designing sound absorber.