Abstract: In apparatus and method for actively reducing a periodic vibration and/or noise, a divergence determinator is provided in which a presence or absence of a higher order divergence of a control of the reduction of the periodic vibration and/or noise is determined on the basis of a sum of two sampled values of at least one of either a drive signal y or a residual wave (vibration or noise) signal e, phases of the two sampled values being mutually deviated from each other by an approximately half period of a fundamental order of the corresponding drive or residual wave signal.

Abstract: A vibration control apparatus for a vehicle equipped with a power unit and a vehicle body is comprised of an active engine mount disposed between the power unit and the vehicle body. A controller is connected to a vehicle body vibration detector, a passenger compartment vibration detector and a drive force detector. The vehicle body vibration detector detects a vibration transmitted from the power unit to the vehicle body through the active engine mount. The passenger compartment vibration detector detects a vibration of a member defining a passenger compartment of the vehicle. The drive force detector detects as to whether driving force of the power unit is transmitted to driving wheels. The controller controls the active engine mount to reduce the passenger compartment vibration when the driving force is transmitted to the driving wheels and to reduce the vehicle body vibration when the driving force is not transmitted to the driving wheels.