The constraint modal and operation modal of a car roof were obtained by testing and analysis. In the constraint modal test the car was impacted by a vibration exciter while in the operation modal test it was impacted by a hub in an anechoic chamber. Comparing the results with the auto power spectrum of the noise at driver’s right ear (driver’s noise), it was found that the noise frequency resulted from the operation modal analysis was closer to the noise peak frequency than that from the constraint modal analysis. By the comparison of the auto power spectrum of the driver’s noise with the average of auto power spectrum of the vibration acceleration at all the measurement points, the roof vibration was found to be the main cause of the driver’s noise in 100 Hz to 400 Hz frequency range. Finally, by adjusting the roof structure, the driver’s noise was restrained.%通过试验分析分别得到汽车顶棚约束模态和工作模态，其中约束模态试验采用激振器激励，工作模态试验采用室内转鼓激励；对比驾驶员右耳处噪声自功率谱密度函数，发现通过工作模态分析得到的频率更加贴近噪声峰值频率；将驾驶员右耳处噪声自功率谱和所有测点振动加速度自功率谱平均值相比较，发现100 Hz到400 Hz内顶棚振动对车内噪声起主要作用。最后，通过调整顶棚结构实现车内噪声的降低。
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