An improved system for monitoring vibration of an electric machine is disclosed. According to one embodiment, sensors are positioned in a plane orthogonal to the motor shaft and each sensor detects vibration along at least one axis of the motor. The sensors are oriented such that the polarity of each sensor is reversed. The pairs of sensors may be used to isolate specific vibrations within the motor. According to another embodiment, a sensor may be mounted directly to the motor shaft. The sensor on the motor shaft directly detects vibrations along the motor shaft. Optionally, a second sensor may be mounted to a fixed location within the motor housing, and the combination of the sensor on the motor shaft and the sensor at a fixed location may be used to isolate specific vibrations within the motor. A motor controller may adjust operation of the motor to reduce the isolated vibration.