There's something fascinating, or foreboding, about a duet by string bass and slide trombone. It is, or has the potential to be, something ridiculously slippery, unanchored, uncentered. No frets, no valves, just glissando run rampant. The instruments can be corralled, of course, by experienced cowhands [see (hear) the duo of Ray Anderson and Mark Dresser, for example], can be coerced to step in line. But the tendencies of the bull fiddle and the sackbut are not to pasture but to roam.

The roamings conducted by the practitioners Joëlle Léandre and George Lewis are intercontinental, at least as suggested by the title of their duo album TransAtlantic Visions. The eventful meeting of these two players — the Frenchwoman Léandre and the American Lewis — of course is itself trans-Atlantic, but the music they played at the 2008 Vision Festival and captured here is also of that thing called "worldly," which we understand to mean not of any particular geography but merely informed, intelligent. The American comes at it with a background steeped in jazz but with an eye focused keenly on the future, the European trained in a formalism which is given the vague appellation "classical" but having studied also with the patron saint of sound John Cage. The ground they travel is the aural abstract expressionism, that rich furrow of free improvisation, that land where sounds exist equally and independently, the genesis not in the respective instruments but the hearts and minds of the players themselves. And in this case those hearts and minds are extraordinarily large.

In other words and in more pedestrian terms, this is anything goes. This is the blurring of musics just as it is the blurring of notes across an unsubdivided continuum. And this is, no doubt, a masterful display. There is plenty upon plenty of musicality within these 52 minutes, plenty upon plenty of momentarily erupting melodies and spontaneously occurring interactions. There is the growl of Lewis's brass and Léandre's voice and there are the illusions of trumpet and violin. But mostly, there is simply a pair of masters at work. Not play, or also play, but still working, hard, structuring the passing moments to span the ocean.