It’s a poorly kept secret that most improvising musicians will play with just about anybody. Since they thrive on collaboration and don’t have to rehearse with a particular result in mind, they often end up recording more often than other musicians. Until a few years ago, improvisers mostly kept to their own community. More recently, though, performers from distinctly non-jazz-based disciplines have been reaching out to them to enrich their own recordings.

Spring Heel Jack are an electronic duo from England, but their American label is also host to jazz pianist Matthew Shipp’s "Blue Series," an ongoing project that has featured one-offs by a number of Shipp’s New York scenemates. Following the Reese’s Peanut Butter Cup principle, the new Masses (Thirsty Ear), credited to "Spring Heel Jack * The Blue Series Continuum," finds the British drum ’n’ bass masters (John Coxon and Ashley Wales) laying down subtle basic tracks that a big group of acoustic musicians (the usual NYC suspects plus British soprano-saxophonist Evan Parker) use as a jumping-off point for collective improvisation.

I assumed that a collaboration of this sort would fail because the jazz guys would be more than a little out of the techno-nerds’ league. But that was just my genre snobbery at work. In fact, Masses is a terrific album — it’s still a novelty to hear improvisation directed by pre-set textures rather than by chord changes or rhythmic forms. SHJ actually play with mutated traditional structures a few times: "Cross" is a set of atonal string loops that seems loosely inspired by the standard "Everything Happens to Me," and Roy Campbell and Mat Maneri respond with viola- and trumpet-shredding parodies of cool jazz licks.

Meanwhile, on the other side of the Atlantic, the Dutch punk band the Ex have been flirting with the international new-music scene for years (including two remarkable albums they made with the late cellist Tom Cora), and they’ve started to work directed improvisation into their live shows. On their new Een Rondje Holland (Ex Records), which is credited to Ex Orkest, they go all out. Put together for the Holland Festival last year, Ex Orkest is a 20-piece big band whose line-up includes Dutch improv luminaries Wolter Wierbos, Michael Moore, Jaap Blonk, and Michael Vatcher. Most of the songs are just reworkings of old Ex standards — "Kokend Asfalt," for instance, is simply 1991’s "State of Shock" with new lyrics in Dutch. But the flurry of instrumentation is even more intense than the Ex usually are on their own, which is saying something.

The Ex are a rhythmic band rather than a melodic one, so adding a huge horn section — i.e., lots of notes — broadens their impact zone instead of deepening it. Every song has a firm structure (having a vocalist — or, in this case, five vocalists — will do that), but the members of the orchestra who aren’t hammering in the rhythms augment the cloud of noise as they see fit; by the end of most of these pieces, they’ve built up an impressive head of steam.

For truly free improvisation, though, you have to go to musicians who are incapable of playing the same thing twice, and composer Dave Soldier has found some in an unlikely place. Thai Elephant Orchestra (Mulatta), credited to Soldier and elephantologist Richard Lair, is exactly what it sounds like: a group of elephants from the Thai Elephant Conservation Center who have been trained to play large, adapted musical instruments. Soldier and Lair built a gong, slit drums, harmonicas, bells, a marimba-like renat, and a theremin, all of which the elephants play with their trunks for about two-thirds of the album. It could easily pass for one of the Los Angeles Free Music Society’s playful recordings of people banging and tooting on whatever’s handy.

The pachyderms aren’t what you’d call great musicians, exactly, but they’re definitely musicians, following their instincts for what sounds good. The disc is filled out by a couple of pieces by humans about elephants, which aren’t nearly as much fun, and by a few collaborations between human and elephantine musicians, which are completely fascinating — it’s usually impossible to tell which parts of the music come from which species. What would the 6000-pound percussionist Phangkhawt sound like playing with the Ex or Spring Heel Jack? Not as creative or precise as the human improvisers, certainly, but sometimes all you want from free music is a great big messy sound.