New tech to block road noises when your car hits obstacles

Researchers from the University of Cincinnati have developed an adaptive, active algorithm that would enable the deployment of a rapid-response sound wave that would counter and, in effect, significantly "erase" the perceived road noise heard within the car's cabin when the auto unexpectedly hits a roadway obstacle like a pothole or speed bump.

"Within the next year, we will verify the real-world efficacy of the algorithm in actual test vehicles with Ford. It's expected that the numerical simulation, when tested in the real world, will reduce road-impact noise perceived by the car driver by three to five decibels," Guohua Sun, lead researcher said.

An active noise control (ANC) system like the mathematical simulation created by the UC team is fundamentally based on the active minimisation of one sound wave (noise caused by a roadway obstacle) by an opposite-phased "mirror" wave.

In other words, noise is heard due to the travel of sound waves. However, any particular noise can be quieted if its sound wave encounters an inverted "mirror," opposite-phase sound wave.

The two waves would overlap; however, while one wave is peaking, the corresponding out-of-phase wave dips. The end result is sound that is significantly diminished.

Such active noise control in automobiles is available in high-end, luxury cars in Japan and in the future from Ford; however, even these ANC systems are used only to negate "routine" roadway noise- the noise of a car traveling at a consistent speed on smooth pavement, researchers claimed.

"There is a real challenge in creating an ANC system that can treat random road noise, the impact sound of a pothole or a bump and other transient responses, such that the sound is minimised within the car's cabin," Sun said.

"The challenge comes because the sound is unexpected and cannot be easily predicted. So, you need a stable, robust algorithm that can efficiently and quickly track such noise and respond to it," Sun said in a statement.

The study will be presented in the INTER-NOISE, the 41st International Congress and Exposition on Noise Control Engineering.