The challenges concerning noise, vibration, and harshness (NVH) performance in the vehicle cabin have been significantly changed by the powertrain shift from a conventional drive unit with an internal-combustion engine (ICE) to electric drive units (eAxles). However, there is few research regarding the impact of electrification on NVH considering the influence of the context such as multi-stimuli and traffic rules during a real-life driving.
In this study, the authors conducted test drives using EVs and ICEVs on public roads in Europe and conducted a statistical analysis of the difference in driver impression of NVH performance based on interviews during actual driving. The impression data were categorized into clusters corresponding to related phenomena or features based on driver comments. Furthermore, the vehicles data (vehicle speed, acceleration, GPS information, etc.) were recorded to associate the driver impressions with the vehicle’s conditions when the comments were made.
Through the statistical analysis of driver’s impression and comments, this study has revealed that the most important factor in improving the NVH marketability of EVs is the enhancement of acoustic phenomena, particularly addressing issues related to whine and whistling noises generated by eAxles. Based on the results regarding the association between a driver's impression and driving conditions, the shift to EVs expands the range of driving conditions in which the whine and whistling noises make a negative impression on drivers, specifically during acceleration and at higher vehicle speeds. Additionally, these noises are less correlated with driver feedback regarding vehicle behavior. Whereas, for achieving improvements of whine and whistling noises, the comprehensive management of the acoustic environment is indispensable, because these noises are masked by road noise and wind noise.