So how does it work? When you connect your account on a Google Home, we ask you to say the phrases "Ok Google" and "Hey Google" two times each. Those phrases are then analyzed by a neural network, which can detect certain characteristics of a person's voice. From that point on, any time you say "Ok Google" or "Hey Google" to your Google Home, the neural network will compare the sound of your voice to its previous analysis so it can understand if it's you speaking or not. This comparison takes place only on your device, in a matter of milliseconds.
This feature will start rolling out today for Google Home users in the U.S., but will expand to the U.K. in the coming months.