The Mimi Switch is uses an earbud containing infrared sensors that measure the inner ear movements resulting from various facial expressions. "An iPod can start or stop music when the wearer sticks his tongue out," says the inventor, Kazuhiro Taniguchi of Osaka University. The device can also be used to monitor your facial expressions for the appropriate levels of cheerfulness. "If it judges that you aren't smiling enough," the inventor goes on to say, "it may play a cheerful song."