Todd Spangler NY Digital Editor“Hey Alexa, what’s another word for ‘creepy’?”In a demo that has drawn comparisons to dystopian series “Black Mirror,” Amazon revealed that it has developed a way for its Alexa voice assistant to replicate the speech of a dead relative — based on less than a minute of recorded audio of the original person.The ecommerce giant showed off the new technology Wednesday at its re:MARS conference, Amazon’s global artificial-intelligence event for machine learning, automation, robotics and space. In a video demo shown at the event, a young boy says, “Alexa, can Grandma finish reading me ‘The Wizard of Oz’?” — whereupon a synthesized voice of the grandmother emanates from an Amazon Echo Dot smart speaker.