As cars become quieter the sound quality of components becomes more critical in the customer perception of car quality. Considering that middle frequency noise plays an important roll for internal noise, the noise signals in the range from200Hz to 500Hz are specially emphasized. Then the acoustic evaluation parameters, such as Sound Pressure Level, Acceleration have been evaluated. Judged from experiences and measuring results, an abnormal noise comes from engine mounts, through the use of dynamic vibration absorber on engine mounts, Vibration on engine mounts and Sound Pressure Level in interior vehicle were greatly improved. At the same time, subjective evaluation also indicated that there was no complaint any more in passenger compartment. Dynamic vibration absorber can properly solve the abnormal noise.

As cars become quieter the sound quality of components becomes more critical in the customer perception of car quality. This requires a need of new evaluation method for the specification of component sounds. Considering that high frequency noise plays an important roll for internal noise, the noise signals in the range from 7000Hz to 8000Hz are specially emphasized. Then the acoustic evaluation parameters, such as Sound Pressure Level, Sharpness and Steadiness have been evaluated. Judged from experiences and measuring results, an abnormal noise comes from Generator, through the exchange of Generator, Sound Pressure Level and sharpness were greatly improved. At the same time, subjective evaluation also indicated that there was no complaint any more in passenger compartment. Low Sound Pressure Level, sharpness can lead to perceived high product quality.