Circuit/System Description

The active noise cancellation system uses three microphones in the vehicle headliner: one above each front seating position, and another above the right side of the second row seat. The amplifier provides a bias voltage to each microphone (+) and (-) signal circuits for operation of the microphone. The microphones monitor the vehicle cabin for undesirable engine sounds. The amplifier uses the microphone inputs and an engine RPM signal to determine the frequency of the undesirable sound.