In the world of speech recognition software, 5.1% is kind of a magic number. Companies that can create software with error rates falling in that ballpark are essentially matching the capabilities of humans, who miss roughly 5% of the words in a given conversation. On March 7, IBM announced it had become the first to home in on that benchmark, having achieved a rate of 5.5%. The breakthrough signals a big win for artificial intelligence that could eventually live in smartphones and voice assistants like Siri, Alexa, and Google Assistant. "The ability to recognize speech as well as humans do is a continuing challenge, since human speech, especially during spontaneous conversation, is extremely complex," Julia Hirschberg, a professor of computer science at Columbia University, told IBM in a statement.