Final answer:
Acoustic glass break sensors should be placed near the glass they are designed to protect to detect the unique resonant frequency of the glass, indicating shattering. They can be mounted on ceilings or opposite walls, with care taken to maintain a clear sound path.
Step-by-step explanation:
Acoustic glass break sensors are security devices designed to detect the specific sound frequency of shattering glass. When installing these sensors, they should be placed near the glass they are meant to protect. This allows the sensor to accurately detect the resonant frequency of the glass which, when matched by a high-intensity sound wave, can cause the glass to shatter.
The sensors must be close enough to pick up the sound of breaking glass, but not so close that they could be damaged by any potential breach. Typical placements include on the ceiling near windows or doors with glass or on the opposite wall, ensuring a clear line of sound detection. They utilize the principle that every piece of glass has a unique resonant frequency. An acoustic glass break sensor listens for this specific frequency, and if detected, it implies that the glass is under stress or has been broken, triggering an alarm.
For example, the event shown in Figure 17.2, where glass shatters as a result of a high-intensity sound wave matching its resonant frequency, demonstrates the kind of detection mechanism by which these sensors operate.