This paper investigates the sound absorption of a multilayer acoustic absorber. The acoustic absorber is consisting of a 3D printed micro-perforated panel, a porous sound absorbing material and an air cavity mounted in front of a rigid wall. The micro-perforated panel specimens are printed with various thickness, hole spacing, and diameters. The sound absorption coefficients of the acoustic absorbers are experimentally measured by using a two-microphone impedance tube method. The experimentally obtained sound absorption coefficients are theoretically validated by using the transfer matrix method. The comparisons show that the measured sound absorption coefficients agree fairly well with the prediction results. By adjusting the hole spacing, hole diameter, and thickness of the micro-perforated panel, an acoustic absorber with high sound absorption peaks can be implemented. The significant improvement of the sound absorption of the acoustic absorber at low to mid frequencies can be attributed to the porous sound absorbing material and the air cavity. The results in this paper provide a new approach to produce micro-perforated sound absorbers for acoustic applications.
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