Anyone with a voice as powerful and passionate as Brittany Howard’s was bound to get noticed fast. Sure enough, the former postal carrier swiftly established herself as American music’s most startling newcomer with the 2012 debut by Alabama Shakes, the raucous rock ‘n’ soul band she cofounded. As if the Shakes weren’t explosive enough, Howard got grittier with her garage-punk side project Thunderbitch. Yet Howard has her softer aspects too, bringing subtlety and grace to the music she makes under her own name as well as her detours into jazz and folk with Bermuda Triangle, her trio with Jesse Lafser and Becca Mancari.