Hyundai Motor Group said it has developed a Road Noise Active Noise Control (RANC) system, which is designed to reduce noise within the cabin of a vehicle.

RANC builds on the group’s current Active Noise Control (ANC) technology, which reduces noise by emitting soundwaves inverted to incoming noise. ANC is a software-driven technology that analyzes the in-cabin sound to decrease engine and road noise.

Conventional noise insulation methods relied on sound insulation and dynamic dampers, which not only increased weight but also failed to block the buzzing infrasound completely. ANC uses lighter parts like microphones and controllers to control the noise and reduce infrasound. The technology is already available in some Hyundai Motor Group vehicles.

However, due to the limitations of noise measurement and analysis technology, the existing ANC was only able to be used when noise was constant and the occurrence of the noise was predictable. For example, ANC technology has been most commonly used to counteract constant engine noise.

RANC technology can analyze various types of noise in real-time and produce inverted soundwaves. For example, the new technology can process different types of road noises, such as resonant sounds created between tires and wheels or rumble sounds coming up from the road.

Working principle

Using an acceleration sensor, RANC calculates the vibration from the road to the car and the control computer analyzes road noise. As its computation and signal transfer speeds are optimized, it takes roughly 0.002 seconds to analyze the noise and produce an inverted soundwave, generated by a digital signal processor (DSP). The microphone monitors the road noise cancellation status and sends the information to the DSP. RANC is able to conduct accurate noise analysis and rapid computation to combat road noise for the driver’s seat, the passenger seat and rear seats separately.

Graphic showing basic components of the RANC technology. Credit: HyundaiHyundai said that based on tests evaluating road surface, vehicle speed and different seating positions, RANC was able to reduce in-cabin noise by 3dB. The company said that level is roughly half the noise level as compared without RANC.

Hyundai said that the research and development process took roughly six years. Development work included help from the Korea Advanced Institute of Science and Technology, WeAcom, ARE, BurnYoung and others.

The company said that in-cabin quietness becomes more important as internal combustion vehicles are phased out. Vehicle interior noise primarily comes from three sources: vehicle powertrain noise, road noise and wind noise. There is almost no powertrain noise from electric and fuel cell electric vehicles, so dampening road and wind noise is a primary focus.

The technology will begin to be applied to an upcoming Genesis model.