What is the function of the Audi A8's Active Noise Cancellation feature?

I've heard that the Audi A8 has Active Noise Cancellation as a feature. How does it work and is it effective?

The Active Noise Cancellation feature in the Audi A8 analyzes and counteracts any unwanted sounds in the cabin, using strategically placed microphones and speakers. This results in a quieter and more comfortable driving experience.

The Active Noise Cancellation feature in the Audi A8 uses a complex algorithm to detect and eliminate outside noises, even at high speeds. It has been shown to reduce cabin noise by up to 3 decibels.