The Deal

• $ for a home-security system plus installation and six months of monitoring ($ value)

Glass-Break Sensors: The Windows Have Eyes

A home-security system knows when there’s motion inside your home or when a window opens, but it can also alert the authorities at the moment an intruder breaks a pane of glass. Read on to learn about the technology that makes this possible. 

Modern glass-break sensors use one of two primary technologies: a microphone that recognizes the specific frequency of glass as it shatters or a sensor that detects the physical vibration of the window breaking. The first type, known as audio discriminators, can discern between the sound of a window breaking and that of a piece of china breaking during your pet bull’s playtime. The second type, called shock detectors, usually consist of a physical device attached to each individual window pane. 

Better, Faster, Stronger, Smarter

Although shock detectors are undoubtedly reliable, audio-discriminating sensors have surpassed them as the more popular option. To aid with their precision, many units on the market today possess the ability to search for both low and high frequencies, which correlate to the thump of a tool striking the window and the higher pitch of the glass shattering—in that exact order.

Bonus Points

• If glass-break detectors are important to you, be sure to keep your windows locked to get the most from your investment.
• Since they can detect sounds from as far as 40 feet away, audio-discriminating sensors are usually invisible to anyone looking in through a window, adding an extra element of security (and surprise).