Active noise cancellation
Active Noise Cancellation (ANC) is used to eradicate undesirable noise with cancellation sound. The system applies the principle of destructive interference, which is also known as the cancellation sound principle. When two sound waves of the same frequency are superimposed, their amplitudes cancel one another if they have the same magnitude and exhibit a phase offset of 180 degrees.
In the car interior, small microphones are used to record the background noise in multiple zones. From their signals, the ANC control unit computes a differentiated spatial sound field. It supplements this with information about engine speed. In all zones in which the system detects noise for which it has been pre-calibrated, it initiates a precisely modulated cancellation sound. The ANC system is always active – whether the sound system is turned on, turned off or set to loud, soft or mute. ANC works with all available factory-installed sound systems.