The acoustic characteristics of perforated pipes have been experimentally studied in terms of transmission loss. This study includes not only the cases of perforated pipes having uniform hole distribution along the length but also those of having nonuniform hole distributions. The major experimental parameters are porosity which is defined as the ratio between cross sectional area of pipe and the total perforated one, and nondimensional wave number ka ; k is propagation constant and a is the distance of perforated holes in axial direction of pipe. The experimental results are compared with the numerical once which consider the detail distribution of hole impedances in axial direction.
