A Compound Micro-perforated Panel Sound Absorber with Partitioned Cavities of Different Depths

The micro-perforated panel (MPP) sound absorber is becoming a good replacement of conventional porous absorbers in building noise control. The MPP absorber is fiber-free and avoids potential harms such as powdered fibers and damage to the person's health. This paper presents a new compound MPP sound absorber architecture with excellent sound absorption performance both on higher sound absorption coefficient and broader absorption band compared with single MPP absorber. The absorber consists of an array of parallel-arranged MPP sub-absorbers with different depths, where different local resonances are apparent and dominate. In this paper, firstly, an analytical method is proposed to look into the mechanism of the absorber architecture design and this method is validated through simulations based on a finite element procedure. Secondly, the acoustic properties from different MPP absorber dimension sets are investigated through simulations with the proposed theoretical method. Results show that the presented MPP absorber can have normal incidence sound absorption coefficients higher than 0.5 over the frequencies from 370 Hz to 2520 Hz, with maximum value of 0.9. This indicates that the proposed MPP absorber provides a good alternative for indoor sound absorption applications in commercial and industrial buildings.