wake word
A wake word is a phrase that causes an Amazon Echo device to begin recording an end user's request so it can be sent to the cloud for processing. When Amazon Echo detects its wake word, it records the next spoken request and sends a recording of the user's request to Amazon Web Services (AWS). Amazon computers in the cloud process the user's request and send back a response or initiate an action.
Amazon Echo users utter the wake word when they want to activate and engage with the device. "Alexa" is Echo's default wake word, but users can change the default to "Amazon," "Echo," or "Computer" if desired. The term wake word is analogous to hotword, which is used to activate the voice user interface (VUI) on Google Home.
While the Echo device is constantly listening, it only records and transmits audio after the wake word has been spoken. Users can review and delete their voice recordings from Amazon servers through the Alexa app or by visiting the Alexa Privacy Settings web page. End users can also request that Alexa play a short tone to indicate device has heard the wake word and audio is being sent to the cloud.
How do wake words work?
The Amazon Echo uses deep learning, an aspect of artificial intelligence, to teach Echo software how to recognize the wake word. Although Amazon Echo is constantly listening, Echo's audio buffer prevents the device from eavesdropping and recording entire conversations.
According to Amazon, Echo devices have a recording buffer of just a few seconds, which is just long enough to detect the wake word. Amazon uses real-world customer voice interactions to help train their neural networking algorithms. When audio recordings are being transmitted to Amazon's cloud-based Alexa Voice Services (AVS), the Echo device will also alert the end user visually. (The thin ring on the Amazon Echo will turn blue and flash.) When the wake word is being changed, the light on the device will briefly flash orange.
All Amazon Echo devices have multiple, built-in microphones that help the device ignore background noise and decipher wake words spoken from a distance. To prevent Alexa from being woken accidentally, companies can submit audio samples to Amazon to have specific instances of the wake word ignored. For example, a company making a television commercial about "Alexa" can submit the audio to Amazon.
Using a technique called acoustic fingerprinting, Amazon can detect when multiple devices are hearing the same command at around the same time (during a television commercial for Alexa, for example). When the Super Bowl between the New England Patriots and the Los Angeles Rams was broadcast in January 2019, an Amazon Echo commercial featuring the actor Forest Whitaker aired. Amazon utilized a recording of the commercial, along with acoustic fingerprinting, to ignore the wake word, "Alexa," whenever Whitaker uttered it.