A Low-Cost System for Road Induced Tire Cavity Noise Control (RTNC)

The transition from ICE to electric power trains in new vehicles along with the application of advanced active and passive noise reduction solutions has intensified the perception of noise sources not directly linked to the propulsion system. This includes road noise as amplified by the tire cavity resonance. This resonance mainly depends on tire geometry, air temperature inside the tire and vehicle speed and is increasingly audible for larger wheels and heavier vehicles, as they are typical for current electrical SUV designs. Active technologies can be applied to significantly reduce narrow band tire cavity noise with low costs and minimal weight increase. Like ANC systems for ICE powertrains, they make use of the audio system in the vehicle. In this paper, a novel low-cost system for road induced tire cavity noise control (RTNC) is presented that reduces the tire cavity resonance noise inside a car cabin. The approach is cheap in terms of computational effort (likewise ICE engine order cancellation) as well as additional hardware components. The signal from only one single-axis-accelerometer is used to estimate the frequency of the tire cavity resonance in real time. The sensor position is chosen to achieve a high signal to noise ratio (SNR) for the resonance which leads to a robust frequency estimation but does not require specific high coherence with interior noise components. The interior microphones and speakers of the vehicle are used to control the narrow-band noise at the estimated frequency. The performance of the system is investigated based on the simulation results as well as measurements in a real vehicle. The results match well and demonstrate that the technology is well understood, allowing potential virtual system tuning based on reliable simulation data. The system shows a high global reduction of the cavity noise in the vehicle's interior.