https://www.theverge.com/circuitbreaker/2017/10/11/16460120/amazon-echo-multi-user-voice-new-feature

The battle of the smart speakers has become a constant back and forth between Amazon and Google. Back in April, Google Home gained the ability to recognize individual voices, which allows the device to personalize its response for everyone in your house or apartment. This way, you’ll get your calendar briefing or curated music playlists when asking Assistant for them, and Google won’t mix up contacts when you call someone with the Home speaker. Today, Amazon announced that Alexa can now do the same thing.

You can set up voice recognition using the Echo, Echo Dot, or Echo Show. Users are asked to read aloud 10 phrases, and Alexa will then use that data to create a voice profile. After that’s done, voice profiles work across other Echo devices and “most” third-party party Alexa-enabled devices.