Glass break detectors use microphones as sensors. Thanks to multistage selective amplifiers and digital signal processing , those detectors are sensitive to sound of broken glass ignoring other sounds (background noise, breaking dishes, hitting glass with keys). Glass break detectors react to high frequency signals as well as to signals from acoustic bandwidth. More advanced glass break detectors solutions use as additional criteria shock wave (pressure variations) that accompanies bending of glass surface before it breaks. Such technologies provide good efficiency and mineralization of false alarms.