How Amazon Alexa got so smart

In December, the company started inviting Amazon Echo users to try out Alexa Guard, a new setting that turns the smart speakers into home security devices. It listens for suspicious sounds when you’re away and sends a smartphone alert if it detects, say, a window breaking and a possible break in.

According to Prem Natarajan, vice president of Alexa’s AI division, Amazon employees had to destroy different types of glass, such as window glass, wine glasses and drinking glasses, with tools like baseballs or hammers to train the technology.