What makes this rhythm section outing so successful is that both drummer Susie Ibarra and bassist Mark Dresser approach it from both the front and the back line. Each, at times, plays rhythm and, at times, melody. But more to the point they each, at times, do both. Or all four, filling the space of a quartet. Dresser hops nimbly between registers, between arco and pizzicato and between deep resonance and fast groove. Ibarra is at her heady best, which is refreshing given the lightness toward which some of her recent projects have veered.

As a duo (and despite some less successful live sets), they are a natural, and seem to be committed to continuing the relationship. The pair previously backed guitarists Eugene Chadbourne and Joe Morris on the overlooked Pain Pen (Avant, 2000), and as on that session they push for complexity without straying or alienating.

The recording itself is rich and intimate, close-miked so that waves of decay circle, and the 15 tracks vary in approach and mood. Tone Time is an unusual pairing of instruments, and works to engaging results.