The output of Brooklyn duo Mouthus consists for the most part, anyway of variations on sepulchral groans. Brian Sullivan's imploding, acidic guitar gestures and Nate Nelson's buried-in-the-mix drumming combine to form the things sweet No Wave dreams are made of: gray, fugitive whorls spinning just out of sight in dark caves. Recent recordings, however, suggest a growing restlessness, a desire to branch out. Last year's For the Great Slave Lakes throbbed and thumped so insistently and peevishly that comparisons could be drawn to raw industrial music. The upcoming Saw a Halo also deviates from Mouthus' winning, dervish formula a few times. "Your Far Church" opens like a roughshod folk song, with acoustic chords and bass drums reverberating solemnly and threatening to overshadow tentative and indecipherable dual vocals that can't be understood; before long, though, Nelson and Sullivan cinch up their arrangement, only to thrash it into rocky, extremist eff-you noise. Later, "The Gift of Sighs" visits Lightning Bolt-like psychedelic ax peel-outs. Perhaps the duo's side projects have had some influence? For a change of pace, they sometimes record and tour with White Rock or Religious Knives projects involving members of the like-minded quartet Double Leopards, with whom Mouthus shares a studio.