For years North American improvisers have gone to Europe to play with like-minded musicians; today the traffic is as frequently the other way .Sputter and Landscape: recognizable are a couple of souvenirs from Hamburg-based trumpeter Birgit Ulher’s recent American odysseys that show her interaction with similarly minded Yank music experimenters. Meanwhile Grammer captures an earlier meeting in Chicago between Portuguese violinist Carlos Zingaro and two locals, one of whom is also on one of the trumpeter’s CDs.

In Europe Ulher works in a variety of international ensembles and seems to have a particular affinity for percussionists. The UNSK quartet, of which she is a member, includes Swedish drummer Raymond Strid, while British drummer Roger Turner is with her in the PUT trio. So it makes sense that on these new CDs she’s partnered with two of the United States’ most inventive sound makers, who are also percussionists: the Bay area’s Gino Robair and Chicago’s Michael Zerang.

Just as Ulher, like countryman Axel Dörner and Boston’s Greg Kelley, is expanding the trumpet’s language, so in their own ways are the Californian and Midwesterner doing the same for the percussion family. Listed as playing energized surfaces and voltage made audible on Sputter, Robair uses synthesized live electronics to extend his kit’s capabilities. Similarly, Zerang’s expanded kit on Landscape: recognizable includes friction drum, wind whistle, xylophone bars, snare drum, bird calls and metal.

Not that anyone is nonplussed during the course of these improvisations. After all, Robair has matched wits with reed experimenters like Britain’s John Butcher and Anthony Braxton; while Zerang has done the same with Butcher and folks like Germany’s Peter Brötzmann. Encountering a metal tube with three valves merely calls for different strategies.

Expanding the aural panorama on Landscape: recognizable, is the wild card: Chicago-based audio artist Lou Mallozzi. He adds his arsenal of turntables, CDs, microphones, organ pipes and amplified voice to the sound miasma Zerang and Ulher create. Mallozzi was also on hand the year before in the same studio, when he, his dismembered and reconstituted sound sources and local cellist Fred Lonberg-Holm hosted another overseas visitor, Portuguese violinist Carlos Zingaro. Together the three make up the Punctual Trio.

Lonberg-Holm and Zingaro are two of improv’s busiest collaborators – each has played with musicians as distinctive as German trumpeter Dörner in the cellist’s case, and French bassist Joëlle Léandre in the violinist’s. Both American string players have also dabbled in electro-acoustics, attaching piezos and processing tools to their instruments for performances and recordings.

In this context, Sputter is practically an acoustic session. From the beginning of the Robair-Ulher meeting thrashing input signals, masticating impulses and hissing oscillations predominate. But you can still hear the puffs of colored air, spattering triplets and buzzing lead pipe movement that can only be created orally.

At various times Ulher bubbles near subterranean pedal tones that swell to aviary caws, throat slurs and eventually piercing shrills – then she adds yelping internal valve lesions. Rubato, often spewing microscopic tones, the trumpeter doesn’t neglect flutter tonguing, tongue-clicking, sudden volume shifts and mouthpiece kisses. She can replicate the creak of a raising coffin lid to meld with Robair’s otherworldly cymbal scrapes, or cackle crone-like to join the percussionist’s static tuning actions. For his part, Robair triggers wave forms that can be compared to a pre-recorded tape running backwards, a vacuum cleaner’s roar, Morse code and insistent doorbell buzzing.

On “A Genius of Trunnels”, for example, he outputs church organ-like striated tones that finally reveal themselves as cymbal and gong battering, while she explores plunger tones and growls from the capillary valves. Eventually, cymbal vibrations mix with the brassy duplication of distant thunder. On The Downy Monsters”, the longest track, Ulher’s near-polyphonic output reaches almost accordion-like compression as air and metal vibrate around single breaths. Completing the impulse as if he too was manipulating another part of her instrument, Robair triggers a complementary pulsating sequence, shoveling and sawing on unyielding hard surfaces.

Similar surfaces get more of a workout on Landscape: recognizable, while the addition of a third sound source makes the session both louder and livelier. Zerang adding aural percussion, plus the pre-recorded voices from Mallozzi’s pre-existing CDs, as well as his microphones and amplified voice give this session more of a verbal quality.

Frequently the pre-existing human timbres are mere gibberish, crowd noises or murky, below the hearing threshold. Sporadically between turntable rumble and mic hisses, however, full words and phrases emerge, though the significance of an announcer intoning “to wait”, “now”, “listen” or “before” in the midst of a group improvisation is a query best left to Mallozzi.

Notwithstanding this, Ulher tone appears harsher, more rhythmic and coarser than on Sputter. Sure there are twitters and warbles, but also many more growling wah-wahs, tongue slaps and stops – the better for counterpoint with Mallozzi’s triggered processed sounds plus the bounces, ruffs and general metrical impetus from Zerang’s percussion collection. Someone who can produce resonating tones from hand action on snare tops or floor creaks, Zerang’s dexterity makes him the perfect intermediary between the electric and the acoustic impulses of his partners here.

Although Zerang’s wind-whistle prowess is no more than serviceable, the chirruping effect – part penny whistle and part bird call – he creates encourages the trumpeter to respond by rubbing textures from her mouthpiece and osculating tongue slaps in a flurry of brassy notes. “Blame Pericles”, the CD’s climatic track has Zerang in proper percussive mode, albeit on metal snare drum. Stripped-down kit notwithstanding, his bull’s eye targeting of the beat, cross patterns with Mallozzi’s gamelan-like tones. Meanwhile, the latter’s organ pipe pops bring quick tongued buzzes from Ulher. Finally she snaps out coda of honks and peeps on top of murmuring and hissing tape noise from the audio artist’s palate.

Without an aural instrument in hearing range, Grammer is more overtly mechanized and electronic than Ulher’s two CDs. At the same time – maybe because of their greater experience with electro-acoustics – Zingaro and Fred Lonberg-Holm appear more assertive when faced with Mallozzi’s media collection. Even more so than on Landscape: recognizable already-existing voice and sound samples predominate. But the string slingers are hardly fazed.

“Predicate” and “Direct Object”, the mid-point tracks that also show the most expository development, are examples of this. On the former an undertone featuring the dulcet voice of a female commentator exists in the same time frame as Zingaro’s warbling partials and Lonberg-Holm’s col legno pacing – the string equivalent of reed tongue slaps. Earlier a piezo-accelerated cello string squeal makes short work of oscillating tones and electrified sine wave sequences from Mallozzi’s objects. Eventually the powerful bow action, growling portamento accompaniment and percussive string and body taps from both strings become paramount.

Similarly on the second tune, a disembodied voice dissolves into sluggish near-gibberish as chromatic cello strums and descending violin spans turn to concentrated arpeggios and scraped pitch-sliding tone layering. Rubbed mic percussion and sequences of hiss and static predominate as the fiddler double and triple stops and the cellist strikes sticks suspended horizontally among his strings. Moving at warp speed from guitar-like pizzicato to legato glissandi and spiccato node expansion, this double string virtuosity is so absorbing that you almost forget Mallozzi, until he finally vibrates jumpy electric piano-like patterns in the tune’s last minute. Elsewhere the sound sculptor’s aural vocabulary expands with replications of V8-bomb explosions, backwards-running sounds, ring modulator clangs and clicks, jaunty circus music jumps, what are evidently an infant’s cry and the plea of another pre-recorded voice for “Jesus Christ right now”.

Overall, however, his musique concrete layering of sine waves and oscillating pitches pales in comparison to the harmonic confluence and rappelling counterpoint from Zerang and Lonberg-Holm, Creating a synthetic ostinato and a droning, high-pitched tone can’t compare to acoustic techniques that amplify the snap of every ricocheting string combination and the slap of every bow movement,

Concluding with a final vibraharp key-like ping, Grammer is most memorable because it shows acoustic and electronic impulses held to a draw. Landscape: recognizable confirms that a year later Mallozzi was more assertive, but not to the detriment of the overall sound. And Sputter replicates how well two committed improvisers can think and create in a recording studio.