Each of these brand-name voice assistants speaks when spoken to, turning on a smart speaker or other voice-activated device that can answer questions. Voice is rapidly emerging as a hands-free medium consumers use for, well, just about anything -- music, news feeds, hints on removing stains, instructions for mixing cocktails. In homes, people use voice commands to adjust interconnected lights and thermostats, and search for -- and even buy -- products and services. Think of cave dwellers huddled around a fire pit enraptured by hunting tales, or a 1940s nuclear family gathered in front of a radio for the next episode of The Lone Ranger. And until recently, forms of entertainment and media that relied solely on voice seemed to be on the decline.