Active Noise Cancellation (ANC)/Active Sound Control System
Both the active noise cancellation (ANC) and active sound control are built into the audio unit. Both systems help eliminate unwanted sound from entering the passenger compartment. There are two microphones mounted in the headliner, one just behind the front overhead console and the other just ahead of the overhead rear light module. The microphones listen for low frequencies entering the passenger compartment and send a signal to the audio unit. The audio unit then creates a sound wave that is sent out through the speakers to eliminate the unwanted sound.
Active Noise Cancellation (ANC) System
The ANC system works to cancel engine booming sound up to about 2,000 rpm. The audio unit receives the engine speed pulse (NEP) from the PCM and outputs a sine-wave-sound through the audio speakers to cancel low-frequency noise from the engine. The ANC system also uses two microphones to detect and monitor low frequency noise in the passenger compartment. The microphones feed information back to the audio unit which adjusts the speaker output to reduce the noise. The ANC also receives input from the door open/close (INTR LT) signal from the MICU. Anytime a door is opened, the ANC system temporarily stops working.
