An alarm system having the capability to self-adjust or self-calibrate itself is disclosed. The system includes an alarm controller and at least one sensor that generates a signal that corresponds to the magnitude of a detected event. The signal evaluator is part of the alarm controller and receives the magnitude signal from the sensor. The signal evaluator compares the magnitude signal to a user-defined or preset alarm sensor sensitivity threshold and generates an alarm signal if the magnitude signal exceeds the alarm signal sensitivity threshold. If repeated alarm signals are generated, an alarm threshold adjuster will adjust the sensor sensitivity threshold to a point where repeated magnitude signals will be ignored. The system will reset itself to the original user-defined or preset sensor sensitivity threshold levels after a predetermined time of no alarm signal generation. The alarm signals generated will activate an alarm annunciator, which generates an alarm.