Abstract: Present day intrusion detection systems frequently cause false alarms by mistaking occupants as intruders, and it is desirable to reduce such false alarms. This invention comprises a processor that employs various software algorithms. The processor receives signals over temporal periods and software algorithms statistically discern various activities, thereby reducing false alarms and detection failures. The software algorithms are adaptive to the level of detected activity such that a rate of false alarms may be predetermined. As such, the processor and software algorithms comprise an artificial intelligence system. This artificial intelligence system may be employed in intruder and vehicle alarm systems composed of a multiplicity of detectors and within such detectors. A second aspect of this invention is an improved infrasound detection method that may be employed in such artificial intelligence.