“I’ve got to say goodbye to the pieces of me that have already died,” sings Ingrid Michaelson on the moody new single “Ghost.” Eschewing the lighthearted sound of her earlier albums, Michaelson has indeed made her most mature and expansive work to date with the deeply personal Human Again. Her albums have become progressively slicker as she’s transformed from coffee-shop singer-songwriter to star. The string arrangements found on her last album, 2009’s Everybody, have been punched up on the sweeping album opener “Fire,” while “End of the World,” with its soaring vocals, apocalyptic imagery and thumping percussion, is downright anthemic. However, the delicately sung indie-pop tunes that made her a television commercial and soundtrack mainstay haven’t entirely disappeared. Songs like “Do It Now” and “I’m Through” are as irresistible and well-written as her previous work, albeit a shade or two darker. It’s a welcome shift from one of contemporary pop’s most vibrant voices. –Juli Thanki