Aidin Vaziri | Samuel T. Herring looks like the kind of guy who would break your knees – or, given his stature, gnaw on them mercilessly – if you ever owed him money. But as the lead singer of the Baltimore indie-pop trio Future Islands, he sounds like the most sensitive soul on the planet. The band won a new legion of followers with a stunning live performance on the David Letterman show last month, during which Herring wore ill-fitting clothes, swiveled his hips like Tom Jones and pounded his chest like a middle-aged Marlon Brando as the other musicians passively powered through their buoyant synthesizer melodies. On the group’s fourth album, emotions spill over in songs such as “Seasons (Waiting on You)” and “Light House,” with the vocalist’s soulful voice erupting into a growl when it all gets to be too much. Then again, what would you expect from a man who cites Sam Cooke and Glenn Danzig as two of his biggest influences?