Hyundai is claiming a "world first" with its "road noise active noise control system," which uses sound piped through a car's speakers to negate road surface noise as well as engine noise for a significantly quieter cabin.
It does so using a very lightweight set of components – far lighter than the hefty noise-absorbing insulation you'd normally run in the underfloor of a car. Accelerometers near each wheel track the vibrations transmitted from the road to the car, and generate an inverse signal that's played through the car stereo to cancel out that sound within 0.002 seconds. This, Hyundai says, enables it to be much more responsive to irregular or changing road noise sounds than microphone-based systems that can't listen, process information and then produce a signal in time to cancel any sound that isn't constant and predictable.
Microphones in the cabin give the system a feedback mechanism, sending information to the signal processor and refining the cancellation signal where possible. The system aims to make things optimally quiet not only at the driver's seat, but the passenger seat and the back seats as well; it's clearly a complex algorithm.
In testing across a range of road surfaces, speeds and seating positions, Hyundai says noise in the cabin was reduced by 3 decibels, which, thanks to the logarithmic scale at which decibels are measured, represents around about a 50 percent reduction in road noise. Hyundai sees active noise cancellation (ANC) as an essential technology in the transition to electric motoring; without engine noise, road and wind noise are even more noticeable.
This is not, however, the first company to concentrate on such things. While Ford and Toyota have sought to implement ANC using microphones in the cabin as the primary input, Bose's system clearly includes accelerometers near the suspension system, and so does a similar system debuted by Lotus more than a decade ago. So while Hyundai has a set of patents under review for the new technology, we're not sure exactly which part of this system is a world first – but we welcome a quieter freeway ride any day of the week.
Hyundai says it'll roll the system out soon on an upcoming Genesis model.
Source: Hyundai