Amazon's voice assistant made considerable gains in 2018 through the continued refinement of machine learning techniques.
Because many voice assistant improvements aim to reduce friction, they’re almost invisible by design. Over the past year, Alexa has learned how to carry over context from one query to the next, and to register follow-up questions without having to repeat the wake word. You can ask Alexa to do more than one thing in the same request, and summon a skill—Alexa’s version of apps—without having to know its exact name.
The benefits of the machine learning improvements manifest themselves across all aspects of Alexa, but the simplest argument for its impact is that the system has seen a 25 percent reduction in its error rate over the last year. That’s a significant number of headaches Echo owners no longer have to deal with.