On their second album, “Sweet Sour,” Britain’s Band of Skulls have refined their alternative blues rock. The trio from Southampton is living proof that 70s-influenced hard rock need not be fronted by a vocalist bellowing like a maniac. In fact, it is their harmonic vocals that emphasizes the catchiness of their songs, as is demonstrated by the title track, “The Devil Takes Care of His Own” and the largely soft “Bruises,” for example. “Lay My Head Down” is a beautiful, soft song with a strong folk feel. It is only topped by the album’s closer, “Close to Nowhere,” a very quiet, atmospheric piece, and probably the best track on the album. At the other end of the spectrum, there is the fabulous sinister rocker “You’re Not Pretty But You Got It Going On.” The balance between midtempo rockers and soft numbers is just right, with “Lies” managing to fuse the Zeppelinesque with the R&B of Destiny’s Child. A catchy album. I don’t see, however, how the band name goes with the music.