Abstract: An apparatus for monitoring and processing of motor currents to determine motor characteristics under various loads. In the preferred embodiment, the invention employs a spectrum analyzer that having a plurality of digitally controlled switched capacitor filters under control of a personal computer. Sampling of both voltage and current simultaneously allows for calculation of instantaneous motor power and power factor, which are used to monitor the motor's performance. An acoustical output, generated under computer control is used to give the operator feedback on the motor's operation. The output signal is derived from low frequency or infrasonic sensing and is then stepped up to a frequency that the operator can hear. This permits the analyst to "hear" the condition of the motor under load. A CRT display to show the frequency spectrum and time display.