Although vehicle acoustics is just one of the many criteria involved in the development of a car, it has steadily gained in importance. On many occasions, the emphasis fields of vehicle development can result in a conflict of goals with acoustics.
In a recent Automotive Megatrends webinar, entitled Sound Quality in Powertrain and Vehicle Development, which was sponsored by engineering solution company FEV, Kiran Govindswamy, Director, NHV, Driveline Systems & Vehicle Integration and Todd Tousignant, Manager, NVH & Vehicle Integration, discussed the key aspects of sound quality development, and how the increasing importance of acoustics in a car is being affected by issues such as electric motors and increasingly efficient powertrains.
Electric vehicle sound design
Increasing demand from both consumers and legislators for more fuel-efficient vehicles has increased the production of both hybrid and electric vehicles. These vehicles are significantly quieter than the alternative internal combustion engine vehicles, and have caused some concern in the industry regarding whether the drivers of EVs will be satisfied with the quietness of their vehicles.
FEV is working in hybrid and future connected vehicles, and Govindswamy noted that sound quality is an important attribute for powertrain and vehicle development. He explained, “Clearly there’s customer expectation of the quality of sound within a particular vehicle, and that expectation in fact drives the perception of sound quality.”
Tailoring vehicle acoustics to suit different OEMs is a task currently being worked on by FEV, and Tousignant noted that it is up to the OEMs to decide where they want their vehicles to be on the scale. “Vehicle noise can be tailored to set a vehicle apart from its competition, and the sound of a vehicle engine can often become a part of its recognition with consumers.” Govindswamy suggested that the expectations of sound also differ from vehicle to vehicle, and while a driver of a sportscar may want to hear the sound of the exhaust system to give a perception of quality, the same quality perception may be achieved by a driver of a luxury car, who would appreciate little or no engine noise inside the vehicle. “Luxury cars are supposed to be quiet and refined vehicles but in sports cars, high levels of sound inside the car are accepted and even desired.”
Alternative powertrains
Decades of in designing brand-specific vehicle sound, based on noise and vibration generated by combustion engines has taken place, but in densely populated areas specifically, environmental pollution due to exhaust gas caused by road traffic poses a serious problem. The arrival of new, efficient powertrains, along with hybrid and electric motors as serious contenders to the combustion engine, has considerably changed the work carried out by companies such as FEV in developing and designing engine sounds.
Tousignant however explained that while the number of vehicles with alternative powertrains is growing, so too is the demand for turbocharged boosted engines, at a much greater rate. This creates a challenge for FEV; in EVs or HEVs working in EV mode, the dominant sound is wind or road noise. “The lack of powertrain noise may be a concern and may cause a disconnect between driver and vehicle,” explained Govindswamy. He also noted that one way around this is through designing sound signatures, something which is being investigated by many companies, including FEV.
It is, however, worth noting what the customer expects and demands, the EV market currently consists of early adopters who want to use green technology, explained Govindswamy, and they are less likely to want to hear engine noise. This may change as EVs gain acceptance in the mainstream. “We need to be more open to designing vehicle engine sounds even for cars that might not have a combustion engine,” he said.
Rachel Boagey
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