Soundgarden’s Chris Cornell has always had a quiet side, even when the iconic grunge band he fronted was raging like a punk-rock Zeppelin. Here, he and producer Brendan O’Brien craft a set of somber acoustic songs with titles like “Dead Wishes” and “Murderer of Blue Skies.” But this is hardly an exercise in folky restraint: O’Brien’s backing tracks and Cornell’s nuanced growl, all the more burnished with age, infuse roots music with alt-rock dynamics. “Nearly Forgot My Broken Heart” begins with mandolin, then adds drums, fuzzed-out psych guitar and stacked vocals to make for an arena-size porch reverie. In their hands, even a finespun meditation like “Worried Moon” can become a backwoods inferno. There are some misses (the heavy-handed, hippie-gospel title track; the Revolver-tinged swerve “Our Time in the Universe”). But for the most part, this is the balance of power and intimacy Cornell has always wanted his solo music to have.