来至官方解释：九代雅阁上的ANC/主动降噪怎么工作的

http://www.honda.co.nz/technology/driving/anc/

How the system works

Active Noise Cancellation (ANC) is designed to dramatically reduce low frequency noise in the interior. The system operates whenever the car is running, regardless of whether the audio system is on or off.

There are two microphones in the cabin area.

The microphones capture low-end drivetrain frequencies entering the cabin, and send a signal to the Active Noise Cancellation unit. The control unit then creates a precisely timed reverse phase audio signal that is sent to an amplifier, which powers the door speakers and the subwoofer positioned on the rear parcel shelf.

In the frequency range below 100 hertz, ANC results in an impressive 10 dB reduction in noise level.

Since the system is designed to cancel low-frequency sound, it doesn’t use any of the audio system's tweeters. The ANC dramatically reduces exterior noise. In the frequency range below 100 hertz, ANC results in an impressive 10 dB reduction in noise level.

简单说，这个ANC主动降噪功能是不依赖于九雅的仪表台内嵌的影音系统，只要开启车内电源，无论是否行车，这个ANC都会一直工作，也确实用到了车载喇叭。所以，可以拆掉更换原厂CD/ DA屏 主机，无需担忧这点，但是不建议更换喇叭单元，这个ANC是依赖原厂喇叭来计算方向声波去抵消低频噪音的。如果车主不在乎可能失去这个ANC功能，可以忽略以上建议。