Application of Microperforated Panel Parallel Baffle Silencers in Ducts

Microperforated panel (MPP) baffle sound absorbers are analogous to glass fiber parallel baffles frequently used in building air moving equipment or large exhaust systems. The MPP baffles in this study consists of two microperforated panels with honeycomb sandwiched between them. The MPP baffles are tested by positioning them in a duct and measuring the insertion loss where insertion loss is defined as the difference in outlet sound power without and with the baffled treatment. It is demonstrated that the insertion loss of the MPP baffle treatments is superior to single MPP sheets positioned in the duct and the honeycomb by itself. A finite element model of the MPP baffle is also developed and results correlate acceptably with the measured results.