Abstract: An improved vibration-responsive device is provided for monitoring the condition of a selected apparatus. The improved device is adapted to be mounted to the selected apparatus and comprises a vibration-responsive transducer capable of generating an electrical output signal when the transducer is subjected to vibrations or shock, an auxiliary transducer capable of producing mechanical vibrations in response to an input electrical signal, and means mounting said auxiliary transducer in force-transmitting relation to the vibration-responsive transducer. The device is adapted to be connected to (1) a monitoring system for monitoring the electrical output of the vibration-responsive transducer (the "primary transducer") and (2) means for selectively energizing the auxiliary transducer with an externally generated test signal. When the auxiliary transducer is energized by the test signal, it will cause the associated primary transducer to vibrate.