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In this work, the noise attenuation characteristics of a three-chamber U-bend hybrid muffler have been investigated. Acoustic performance is quantified by the Transmission Loss (TL) parameter. One-dimensional Transfer Matrix based Muffler Program (TMMP) and three-dimensional Finite Element Method (FEM) have been used for the prediction of the TL of the muffler. Presence of perforated baffles necessitates use of the Integrated Transfer Matrix (ITM) approach for the one-dimensional analysis because the sound fields in the adjacent chambers would be multiply coupled with each other, and for the 3D FEM analysis LMS Virtual Lab software has been used. The mean flow distribution in each of these configurations has been evaluated by means of a lumped flow resistance network. The resulting values of the grazing flow and bias flow have been used to calculate the perforates' acoustic impedance.