Circuit/System Description

The Active Noise Cancellation system has three main components: Three microphones, the audio amplifier, and the vehicle speakers.

The 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 two inputs to determine the frequency of the undesirable sound. The amplifier then calculates the appropriate cancellation frequency and outputs a cancellation signal (audio tone), which in turn sends the signal to be output by the vehicle speakers.