Active Noise Cancellation Description and Operation

Active Noise Cancellation Description and Operation

The entertainment system on this vehicle may have several different configurations. To determine the specific configuration of the vehicle, please see the Service Parts ID Label, and refer to RPO Code List (Avalanche and Escalade) ([1][2]Application and ID)RPO Code List (Escalade ESV, Suburban, and Yukon XL) ([1][2]Application and ID)RPO Code List (Tahoe and Yukon) ([1][2]Application and ID).

Note: The Active Noise Cancellation system is only available on certain Cadillac and GMC vehicles equipped with the 6.2L (L94) engine.

The Active Noise Cancellation system is a method used to reduce the perception of certain undesirable sounds generated by the engine into the vehicle cabin. The systems uses microphone and engine speed signals, software integrated into the amplifier, and the vehicle speakers to determine and generate the correct frequencies needed to achieve the desired reduction.

Three microphones are located in the headliner to monitor noise/sounds in the vehicle cabin, and are directly connected to the amplifier. The amplifier also receives a discrete engine speed (RPM) signal from the engine control module. The amplifier processes these inputs to determine the frequency of the undesirable sound. The amplifier then calculates the appropriate cancellation frequency and outputs a cancellation signal (audio tone) to the vehicle speakers to reduce the perception of undesirable sounds by the vehicle occupants so the vehicle cabin appears quieter and without vibration.

Active Noise Cancellation Operation

The main components of the Active Noise Cancellation system are:

* 3 microphones in the vehicle headliner: one above each front seating position, and another above the right side of the second row seat.
* A discrete engine speed (RPM) signal from the engine control module to the amplifier
* Active Noise Cancellation electronics and software integrated into the audio amplifier
* the vehicle speaker system, connected to the amplifier, to output the desired cancellation frequencies

The Active Noise Cancellation system is operational under the following conditions:

* The amplifier has passed all self diagnostic checks
* All doors/liftgate are closed
* Battery voltage is between 9.5 V and 16 V
* The vehicle cabin temperature is less than 140°F (60°C)
* Engine speed is between 550 and 3000 RPM