content: Typically, Google Home devices only respond to the wake phrase, such as “Hey Google” or “OK Google.” But in this case, the device responded to a sound made by a smoke detector – meaning the speakers were actively listening for all sounds.  You'd have to be pretty fucking stupid to not realize these devices are ALWAYS LISTENING. How else can it hear the wake phrase? The only difference is how it responds. I guarantee you there are more terms and phrases it's designed to trigger on, without responding to the user, but recording and forwarding the conversations to Google/ChInA.