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Drivetrain noise from heavy off-road vehicles mainly includes engine noise, drive shaft noise, wheel-side gear noise, tire pattern noise etc. They are the main noise sources for such vehicles as they greatly influence the ride comfort of the passengers inside. This paper solved the drivetrain noise problems of a heavy off-road vehicle using the method of active noise control (ANC). Firstly, the vehicle is benchmarked and the noise problems are analyzed, while the noise sources are identified by analyzing the transmission principles of the drivetrain. Secondly, ANC strategies are made for the vehicle based on the noise profiles under various operating conditions. Thirdly, the multiple parameters for ANC are computed from simulations modeling the vehicle in idle, constant speed and acceleration respectively. Lastly, road tests are conducted using the multiple parameters from the simulations and a noise reduction of 2-4 dB can be achieved in the whole vehicle.

Acoustic performance of auto interiors is definitely important to control the NVH (noise, vibration, and harshness) performance inside a vehicle, and it is determined by the material parameters, such as density (ρ), thickness (d), open porosity (OP), airflow resistivity (σ), tortuosity (T), viscous characteristic length (VCL), thermal characteristic length (TCL), young's modulus, poisson's ratio, and damping coefficient. Firstly, by making different felt samples (of different surface density and thickness), the sound absorption performance and related parameters were obtained. Then the correlation between the parameters and the sound absorption coefficient (SAC) was summarized. Through this method, database of acoustic parameters and the corresponding SAC for porous materials can be established and sound package design and adjustment can be easily conducted based on the database.