Hyundai develops advanced anti-noise technology

Road noise is something that the motorist hears, writes Iain Robertson, which can be exceptionally distracting, repetitively annoying and ultimately disturbing; a good reason for one carmaker to invest in next step technology to eradicate it.

When Ford launched its Puma (Fiesta-based) compact coupe model, it also introduced the sonic feedback tube. Closely akin to an open stethoscope attached to its engine’s cylinder-head, in reality it was a simple feedback plastic pipe running from engine bay to the car’s interior. The idea was to introduce engine intake ‘roar’, in order to enliven the cabin driving experience, without breaching exterior noise legislation. It worked for some people (many others requested it be removed).

Just a few years later, Renault went a step further by developing the sound symposer for its sportier models. Using the R-Line touchscreen, the driver could reach a page that listed everything from a Clio rallycar to a Bultaco trials bike; a choice of around ten different sounds connected by a not dissimilar sonic tube to Ford’s set-up, with the ‘advantage’ of introducing several alien soundtracks. Once the initial novelty had worn off, it was readily ignored.



While tuning firms will replace entire vehicle exhaust systems (some of which are illegal for road use) with the intention of producing a racier soundtrack on all manner of vehicles, from a hopped-up Corsa, to a race replica Nissan Skyline, or Subaru Impreza, very little can disguise the extraneous noise phenomenon known as road roar (transmitted from tyres and suspension systems), which may even include wind roar (caused by wiper blades, door mirrors and roof rails). In its least intrusive form, it can be little more than a gentle rustling sound; in its worst form, it can become a heterodyning racket to drive you slightly mad.

Hyundai has developed RANC, which builds on its current Active Noise Control (ANC) technology, by reducing noise actively, emitting soundwaves inverted to counteract incoming noise. It is a software-driven technology that analyses the in-cabin sound to decrease engine and road noise, rather than the passive method of blocking noise through sound insulation, which adds weight but fails to block the buzzing infrasound completely. In contrast, ANC utilises lighter parts like microphones and controllers to reduce infrasound more efficiently. 



Hyundai has monitored that it takes about 0.009s for road, or engine, noise to reach cabin occupants’ ears. With RANC technology, Hyundai can improve in-cabin quietness significantly. The new system analyses various types of noise in real-time and produces inverted soundwaves in just 0.002s. Resonant sounds created between tyres and wheels, or rumbling from the road surface, can be removed effectively. As these extraneous noises are even more obvious on EVs, where there is no engine noise to contend with, cabin serenity is even more important.

MSG Summary

Some natural in-car sounds can lead to driver drowsiness and, within the next two years, fresh EU legislation is going to lead to a broad mix of anti-drowsiness alert systems. Hyundai has simply got there first.

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