Virtual Car Sound Synthesis Technique for Brand Sound Design of Hybrid and Electric Vehicles

摘要

One of the practical consequences of the development of low CO_2 emission cars is that many of the traditional NVH sound engineering processes no longer apply and must be revisited. Different and new sound sources, new constraints on vehicle body design (e.g., due to weight) and new sound perception characteristics make that the NVH knowledge built on generations of internal combustion-powered vehicles cannot be simply transferred to Hybrid and Electric Vehicles (HEV). Hence, the applicability of tools must be reviewed and extensions need to be developed where necessary. This paper focuses on sound synthesis tools as developed for ICE-powered vehicles. Because of the missing masking effect and the missing intake and exhaust noise of the Internal Combustion Engine (ICE) in electric vehicles, on one hand electric vehicles are quieter than traditional vehicles. On the other hand, other components such as HVAC system, alternator, vacuum pump, power-steering pump, cooling systems, transmission systems, inverter noise, etc., become more important and generate new complex sound signatures. Typically, their interior noise is well-defined by high-frequency noise components which can be subjectively experienced as annoying, hence the increased importance put to sound quality aspects and perceptual-relevant NVH studies. In the paper, a Virtual Car Sound (VCS) synthesis technique for HEV is designed. This approach turns out to be a very helpful engineering tool to design a brand specific sound and allows reproducing typical sound features of HEV during real-time driving simulation based on a Sound Quality Equivalent Model (SQE). Several SQE models were constructed for different powertrains of HEV in various engine conditions. Finally, the results of the sound metrics and listening tests indicate a comparison between the synthesized sounds and the original sound recordings.