Abstract: The roughness of vehicle interior noise during acceleration is analyzed and improved in this paper. Firstly through the analysis on the frequency characteristics of vehicle interior acceleration noise, the main cause of the roughness of vehicle interior noise is determined to be the half order noises. Then the possible noise transfer paths are investigated and the results show that the vehicle interior half order noises stem from the vibration of powertrain and transmit into the vehicle through the side bracket of transmission mounts. Finally improving schemes of reducing the stiffness of engine mounts and increasing the dynamic stiffness of the side bracket of transmission mounts are adopted. As a result, the roughness of vehicle interior noise is reduced and the quality of vehicle acceleration noise is enhanced

Key words: vehicle interior noise, roughness, half order noise, transmitting path