“Turns out there’s a gap between the kinds of sounds that people and computers understand as human speech. Last summer, a group of Ph.D. candidates at Georgetown and Berkeley exploited that gap: They developed a way to create voice commands that computers can parse—but that sound like meaningless noise to humans. These “hidden voice commands,” as the researchers called them, can deliver a message to Google Assistant-enabled Android phones nearby through bursts of what sounds like scratchy static.”
May's Blog 