Audio optimization has become a mainstream issue for today’s auto designers. From compensating for the absence of engine noise to keeping sound levels down in the vehicle interior, audio synthesis and noise suppression solutions can help.
In seeking ways to counter rising fuel prices and lessen environmental impacts, the auto industry is staking out two key trajectories. One is the industry's commitment to lightweight design. The new VW Golf, for instance, is over 100 kg lighter than its predecessor. The other trend is the toward hybrid and electric vehicles that can complete at least part of a journey solely on electric power.
What both developments have in common is the challenge they present for vehicle noise optimization. The lower the vehicle’s target weight is, the less material can be installed to reduce noise, meaning that noise penetrates the vehicle interior (and passenger ears) unmitigated. Electric motor-powered vehicles, on the other hand, by their very nature emit little or no noise at all. As a result, pedestrians are unable to hear an electric vehicle until it is virtually upon them – or worse still, they fail to hear the car at all. Moreover, the lack of engine sound exacerbates the impact of other vehicle noise, meaning that road or wind noise, or wind may be perceived as relatively loud in the vehicle interior.
To counteract these effects, auto manufacturers need effective systems which can synthesize sound in electric vehicles to warn pedestrians, and that can also suppress interior noise successfully. A solution that excels at both, external sound synthesis and internal noise suppression, is HALOsonic, a joint development of HARMAN and the British developer Lotus Engineering.
Figure 1: Complete audio synthesis and noise cancellation system in a car