Techniques to improve the low frequency and broadband performance of microperforated panel absorbers

Abstract

Microperforated panel absorbers can be considered as the combination of the perforated panel and backing airspace. It has been demonstrated that partitioning the airspace improves performance. Additional performance improvements can be obtained by varying the depth of the backing cavity, adding resonators behind the panel, or using double leaf panels. Each of these configurations is first considered for a single cell backing using plane wave simulation. Comparisons are made to impedance tube measurements with acceptable agreement. Following this, the diffuse field sound absorption for each configuration was measured in a small reverberation room. Each test sample consisted of a 0.6 m x 0.4 m panel with a backing cavity partitioned into 24 equal size cells. For the double leaf configuration, the cavity betwen panels was honeycomb partitioned but the backing cavity was unpartitioned.