Meet the woman behind Amazon's Alexa

One-quarter of all American households now have an Amazon Echo powered by Alexa. But the surge in popularity of these virtual assistants comes with new questions about convenience, and privacy -- especially as the company looks to make the smart speaker more "human." Alexa has captured 70 percent of the voice market share in the United States, according to Alpine AI, with customers turning to the device for anything from playlists to recipes to finding their phone. It's become a major source of revenue for Amazon, in particular because it generates larger spending from Amazon Prime members, according to a new report by Consumer Intelligence Research Partners. NBC News obtained exclusive access to Amazon's Seattle headquarters and an interview with the executive in charge of Alexa, Toni Reid, to learn a little more about the future of this pint-sized device.