Glasbruch-Erfassungsvorrichtung

摘要

A first wave of a glass breaking sound has a sharp peak due to an impact sound and thereafter it attenuates rapidly. The attenuating characteristics of the first wave are measured by comparison (6) of the level of detected sound with a predetermined fraction of the peak level (4), after a predetermined time has elapsed since detection of the peak value. Alternatively, the level of the last peak in the impact wave may be compared with the peak level. From this comparison, it is determined whether the detected sound was that of breaking glass. Since the original waveform obtained by a microphone includes noise, the low frequency component is eliminated by a high pass filter (3). Also, since the glass breaking is detected by attenuation of the first wave, the detection can be carried out quickly.