ACTIVE NOISE CANCELLATION OF TONAL NOISE BY MANIPULATING CHARACTERISTIC ACOUSTIC MODES

To reduce engine noise in the cabin of an aircraft a plurality of error microphones is deployed at predetermined locations within the cabin to produce error microphone response signals associated with the engine noise in the cabin. Engine vibration inputs are obtained from sensors coupled to the aircraft engines. A processor is used to code the error microphone response signals into an encoded modal response in the cabin through a coding matrix. A processor is used to apply an adaptive filter to determine a plurality of modal signals needed to cancel the encoded modal response in the cabin. A processor is used to decode the modal signals into speaker input signals through a decoding matrix. Speaker input signals are then sent to a plurality of speakers to reduce the engine noise in the cabin.