For decades, percussionist Hamid Drake and reedist Ken Vandermark have sustained a partnership founded upon a deep engagement with the history of free jazz. Both within and outside the DKV Trio, their long-running ensemble with bassist Kent Kessler, their improvisations often arise from rhythmic foundations. But they’re also restless explorers, and on Open Border a pair of Italian musicians helps them move into new territory. Neither Gianni Trovalusci nor Luigi Ceccarelli has much background in jazz. The former is a classically trained flutist who plays ancient and contemporary repertoire, while the latter is a composer and electronic musician; each has contributed to experimental theater and dance performances. Over the course of a 35-minute improvisation recorded live in 2018 at the festival Forli Open Music, the quartet delves into an unstable sound environment where Drake, Trovalusci, and Vandermark can never be sure just what Ceccarelli’s sound processing might do to their instrumental voices. The taps of key pads blow up like soft explosions, and parts of Drake’s drum kit seem to freeze while others flow freely through the open spaces between the two woodwind players. Their darting gestures coalesce and disperse like a flock of birds infiltrated by tiny avian robots. v