New Harman active road noise cancellation technology enables use of lighter weight materials without vehicle noise compromise

24 October 2014

Harman, the premium global audio and infotainment group, is expanding its HALOsonic suite of noise management solutions, which the company has co-developed with Lotus Engineering using patented Active Noise Control Technologies. (Earlier post.) Harman’s new Road Noise Cancellation (RNC) technology minimizes unwanted noise generated when the vehicle tires roll across the road surface. RNC, which is presently ready for market implementation, enables automakers to use lighter weight materials and improve fuel economy without compromising on vehicle noise levels.

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In pursuing ways to lessen the environmental impact of vehicles and raise fuel efficiency, automakers are reducing vehicle weight, often by using less noise-dampening insulation in the car’s interior. The use of lighter materials, however, increases perceptible road noise inside the vehicle, which then penetrates the interior—and also compromises the audio experience of the on-board infotainment system.

Traditional NVH (Noise, Vibration, and Harshness) methods have difficulties mitigating these issues satisfactorily, and these technologies also tend to add weight, which cancels out the fuel economy effect of using lighter materials.

The Harman HALOsonic RNC solution is based on the principle of using “anti-noise” to counteract road noise. To implement RNC, the chassis of the vehicle is fitted with accelerometers which enable the system to measure correlation of vibration coming from the road and the resulting noise inside the cabin. Subsequently, the proprietary algorithm in the controller creates inverse sound waves (coming from each speaker) through the car’s audio system to cancel out the noise caused by the road-induced vibration.

It is also able to cope with the broadband nature of road noise, with its wide range of frequencies. The HALOsonic RNC solution can reduce the peaks of the noise across the target frequency range, creating a quieter experience within the vehicle cabin. With RNC, Harman’s uses its patented True Audio technology to ensure that only unwanted engine or road noise is cancelled, while preserving music signals in a similar audio range.

HALOsonic consists of a suite of noise management technologies to improve noise levels and to enhance and contour sound inside and outside the vehicle. In addition to RNC, HALOsonic comprises Engine Order Cancelation (EOC) and internal as well as external Electronic Sound Synthesis.

External ESS (eESS) generates sound primarily for hybrids and electric vehicles, creating the authentic sounds which drivers and pedestrians are familiar with from combustion engines, thereby increasing safety both for drivers and other road users. Internal ESS (iESS) serves to generate unique sound signatures for vehicles to contour and accentuate the engine sound.