Picture this: you're alone at home, it's dark outside, and there isn't so much as the squeak of a floorboard to disturb you. And then, out of nowhere, your Amazon Echo bursts into song. Not a tune you asked for, mind you. But an endless, eerie "lalala" that goes on and on. You didn't say the wake word "Alexa" to summon the Artificial Intelligence (AI) assistant that powers the popular line of Echo smart speakers, but it just started on its own a…