How to set up Alexa Guard on an Amazon Echo
If an Echo hears a window break, it can send you an alert to your phone along with a live video feed if you have an Echo with a camera on it, like the Echo Show. An alert includes a 10-second audio recording of the glass breaking and anything else the Echo heard, but it otherwise doesn't listen unless you speak Alexa again.
It will also send alerts if a smart smoke alarm or carbon monoxide alarm goes off. If you configure it, Guard can also automatically turn on smart lights at certain times while you're away, and it will automatically turn them on and off on a schedule as if you're home.
"Alexa uses machine learning to determine the right lighting activity for your home based on lighting usage across customers," Amazon said.
Amazon said it "hired licensed contractors to break real glass in a testing lab," to help prevent false positives and to detect the actual sound of breaking glass. "This team broke hundreds of different windows, in different sizes, including single pane and double pane, with a variety of instruments including crow bars, hammers, bricks, baseball bats, and more," the company explained in an email to CNBC.