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排气噪声是后置柴油机客车的主要噪声源，排气消声器是降低排气噪声的主要部件。用二维声学边界无法建立消声器的降噪模型，用插入损失评价消声量，边界元模型计算结果与客车行驶噪声测试结果吻合很好，证明计算模型可应用于消声器选型计算或优化设计。实验证明消声器外包隔声材料在全频程有降噪效果，１ｋＨｚ以上高频段降噪效果更好，可预见较低的声穿透系数的双层消声器有可观的降噪潜力，应积极研制。
Exhaust noise is the main source of noise for rear diesel passenger cars, and exhaust mufflers are the main components that reduce exhaust noise. The noise reduction model of muffler can not be established with two-dimensional acoustic boundary. The noise attenuation is evaluated by insertion loss. The calculated results of boundary element model are in good agreement with the test results of passenger noise. The results show that the calculation model can be applied to the selection calculation or optimization design of muffler. Experiments show that the muffler outsourced acoustic material has a noise reduction effect in the whole frequency range and the noise reduction effect is better in the high frequency range above 1 kHz. It is foreseeable that the low acoustic penetration coefficient double-layer muffler has considerable noise reduction potential and should be actively developed.