Contribution analysis of vehicle exterior noise with operational transfer path analysis

Vehicle development regarding the emitted exterior noise is a challenging task. In addition to stringent legal requirements to reduce noise exposure, also high expectations of the sound quality have to be considered during the development process. In order to manipulate the vehicle exterior noise in a manner more efficient than trial and error, knowledge about the vehicle’s sound sources, and their contributions to the overall noise is essential. In order to analyze the contributions of the several sound sources of a vehicle to the exterior noise Operational Transfer Path Analysis is used in the presented experiment. Therefore, transfer characteristics are estimated from measurements of the vehicle in typical operating conditions on an acoustic roller dynamometer. These data are used to synthesize the contributions at the response positions, i.e., the microphones of a simulated pass-by array, which also allow the simulation of the contributions during a pass-by measurement. Outcomes of the Operational Transfer Path Analysis are comprehensible contributions of the dominant sound sources to the vehicle exterior noise. The validation of the analysis results shows very good accordance between the simulated and measured overall vehicle exterior noise.