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Perforating certain layers of laminated material can improve the sound absorption performance of the material. The hole size, shape, angle, spacing and pattern can be tuned to improve sound absorption in a certain frequency range using a validated acoustical model. The model is based on a numerical calculation of acoustical properties of porous multi-layers using a transfer matrix method in the context of the Biot theory in NOVA software. An additional calculation of airflow resistivity and porosity from the hole size and hole spacing is also conducted. The model predictions agree with the testing data. Based on this model, the acoustical performance of the material can be optimized to meet vehicle acoustical requirements. The vehicle level SEA models are used to examine the effects of the perforation on the vehicle interior acoustics.