A method and apparatus to cancel gear vibration and noise by imposing a canceling drive torque or force on a driven gear set. Sensors receive information and produce an error signal representative of the vibration and/or noise generated at meshing gears. The error signal indicative of vibration...http://www.google.ca/patents/US5809843?utm_source=gb-gplus-sharePatent US5809843 - Active cancellation of noise at gear mesh frequencies for a gear assembly under load 
