“They start at near stillness—a few notes creak from the nylon strings of an acoustic guitar, and a synthesizer shifts so slowly between notes that it doesn’t seem to move at all. Even the baritone of Lenny Smith, half of the dimly lit duo Barren Harvest, seems to move in careful gradation, treating each word of “Heavens Age” like an event. That slow motion subsists for most of Subtle Cruelties, th”