Micro-perforated panel sound absorbers with an array of partitioned cavities of different dimensions

This paper presents improved compound micro perforated panel (MPP) sound absorber architectures with broader absorption frequency bands compared with single MPP absorber. The absorber is followed the design of quadratic residue diffuser (QRD) that consists of an array of parallel-arranged MPP sub-absorbers with different cavity widths and depths, where it was shown that different local resonances are apparent and dominates. In this paper, an analytical method is proposed to look into the mechanism of the absorber architecture design and 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 normal incidence sound absorption coefficients of the modified QRD-backed MPP absorber can higher than about 0.5 over the frequencies from 370 to 2500 Hz.