Abstract
This paper proposed a new method which can reduce the noise in the duct by use of the perforated panel. First, in order to analyze the acoustic field in the duct with the perforated panel, the theory of the acoustic property of the perforated panel was established and the validity of the theory was checked by calculation and experiment. Second, in order to calculate the acoustic field in the duct by boundary element method (BEM) more exactly than the conventionally method, new analysis methods on BEM were proposed which can calculate the acoustic filed including the effect of the sound attenuation on the rigid wall and can calculate the acoustic field separated by the perforated panel. Finally, noise reduction performance of the perforated panel was measured by use of an experimental apparatus imitated a fan duct and was calculated by BEM, and results of the experiment and calculation showed the effectiveness of attaching the perforated panel to the duct.
