The interactions between reedist Ab Baars and guitarist Terrie Ex on Hef (Atavistic) are considerably louder and more chaotic than your typical collection of duets. A charter member of the ICP, Baars commands a vast vocabulary on tenor saxophone and clarinet, ranging from John Carter-like cries on the latter to knotty, Archie Shepp-tinged phrasing on the former, but he’s on new turf with the guitarist, a long-time member of mighty Dutch anarcho-punks the Ex. The guitarist may lack Baars’ technical training, but he’s got no shortage of imagination, molding an impressive plethora of ideas from slate-gray guitar tones. Whether it’s truncated chords, ear-piercing string scrapes or percussive patter, Terrie sees his instrument as a remarkably flexible sound generator, with great sensitivity. On the 14 texture- and color-based dialogues he and Baars stumble upon a beguiling and rigorous style of communication that ranges from assaultive (“Oud Over”) to almost meditative (“Pets->Knerp”); it forces each participant to struggle with a relatively foreign musical milieu. They succeed brilliantly, with no apologies for occasional brashness.