The reason I brought up Siri and Ok Google is that they're doing the same thing as Alexa with their always-on microphones: they're trying to detect a "wake word

The reason I brought up Siri and Ok Google is that they're doing the same thing as Alexa with their always-on microphones: they're trying to detect a "wake word" ("Alexa", "Hey Siri", "Ok Google"), and once they do they take the recent audio and parse it for commands.