Celebrated during the last few years as the most gifted and ambitious young pianist in jazz, Vijay Iyer engages in a culturally grounded musical conversation with fellow Indian musicians Prasanna and Nitin Mitta. Iyer and guitarist Prasanna supply the nine compositions, but it's tabla player Mitta's hand drums that propel "Tirtha," cementing this genre-free experiment with north Indian classical grooves. In the early going, the trio meets force with more force, Iyer's "Duality" and Prasanna's "Tribal Wisdom" serving as vehicles for the instrumentalists to demonstrate their flair for the intense. The closing numbers (Iyer's "Remembrance" and Prasanna's "Entropy and Time") are polar opposites-peaceful, wave-like improvisations lapping across Mitta's swirling rhythms. While Iyer sticks to a jazz vocabulary that includes dissonant chords and single-line lyricism associated with Keith Jarrett, Prasanna, a native of south India, alters his attack on each tune. He proffers the bended staccato of the sitar, straight-ahead rock solos and some jazzy swing. The music is at its best when it emulates an animated conversation, one voice leap-frogging the other with no one losing sight of the central theme.