Disturbing background noise and unwanted noise inside the car impair the driver's concentration, communication with
passengers and the audio sound from high-quality audio systems. These disturbing exterior and interior noises, which are caused by the road surface, the tires, the wind and the engine, must be reduced. There are several technical approaches to noise reduction: Road Noise Cancellation (RNC), which reduces or cancels rolling noise, and Engine Order
Cancellation (EOC), which aims to reduce engine noise.Road Noise Cancellation is concerned with rolling, road and tire noise that can be heard inside the car. These noises are reduced by acoustic countercompensation. They are recorded, rotated in phase
and fed in antiphase via the acoustic system. Due to the superposition with the disturbing noise, this noise is only perceptible in a reduced form. This procedure ensures a lasting improvement of the noise inside the car. Engine Order Cancellation also works with noise compensation.
However, the compensation signal is derived from the engine speed. This is used as a reference for the phase-rotated sound signal.