Fiddles, cellos and their stringed cousins, can make a most desolate and longing sound — a sound that is distinctly American. The Brother Brothers of Brooklyn really know how to make desolation sound lovely. Identical twins, Adam and David Moss create harmonies that only two people with essentially the same voice can make. Their folksy acoustic songs require attentive listening because they’re not just songs, they’re stories — the cornerstone of the best folk music. The Brother Brothers will be at the Parlor Room tonight as part of the Back Porch Festival this weekend. Doors open 6:30 p.m and the show starts at 7:00 p.m. $12 in advance and $15 at the door. The Parlor Room, 32 Masonic St., Northampton.