【摘要】 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。更多还原

【Abstract】 The exhaust noise is one of the main noise sources and the muffler is an important assembly in noise reducing of the bus. The noise reducing model of the exhaust muffler based on B.E.M. is built and the sound level evaluated ability of sound elimination by insertion loss and calculated by the model agrees well with the result of the bus travelling test. It is indicated that the B.E.M. model is useful in choosing and designing of the muffler. According to the test, there is a reduced noise effect in total frequency bands with a layer of the soundproof material wrapped round the mumer, especially upon 1kHz. It is predicatable that the double-layer muffler having low sound-transmission coefficient would have more capacity for noise reducing,so it must be developed.更多还原