Going mano à mano with two of the founder of European Free Music — German division — is no challenge for the faint-hearted, especially when your opposite number is packing a double bass or a grand piano respectively, and your only weapons are a couple of small metallic flutes.

But Lisbon-based Carlos Bechegas has the talent and technique to hold his own in these situations. Listening to these duo dates, recorded four years apart, you hear how his playing has evolved still further since the first meeting. The output is more confident and his delivery more relaxed, yet building on the high standard he already set.

On the 13-part suite that makes up 1999’s Open Secrets, Bechegas’ partner is the late bassist Peter Kowald (1944-2002). On the five cuts on Open Speech — recorded in 2003 — it’s pianist Alexander von Schlippenbach, who knows a thing or two about wind instruments, having worked in trio formation with saxist Evan Parker for more than 30 years.

On the 2003 session, Bechegas uses vertically blown physicality and a staccato attack to give his playing a rough, buzzy quality as well as soaring, skittering aviary timbres. Using all his keyboard resources, Schlippenbach responds in kind.

“Speech II”, for instance, begins with the pianist exploring a dark, left-handed dynamic of broken octaves as the flautist sluices down the scale with an airy touch and flies in double-tongued circles around piano cadenzas. This spherical theme is echoed by Schlippenbach with dramatic, vibrating accents. On his own, Bechegas, shrills flutter- tongued double counterpoint, then, a cappella, wheezes out drones from the mouthpiece. For a finale, the pianist pummels clusters of heavier accented notes, while a sly Stride reference give them extra vibrations.

With Rahsaan Roland Kirk’s re-imagining of the flute one aspect of Bechegas’ vocabulary, Schlippenbach uses piercing staccato lines filled with skittering vocalizing and emotion to reveal his influences as well. A long-time Monk fancier, on “Speech V”, Schlippenbach’s full-force ringing pressure and repetitive cadenzas bring the older American pianist’s style into focus. That’s in advance of a climax that features the reedist scatting wordlessly between flute breaths and the keyboardist outputting prestissimo.

Choruses of throaty, grumbling mouth sounds, glottal stops, buzzing Bronx cheers plus aviary twitters and whistles — not to mention rhythmic foot stamping — are a part of Bechegas’ novel presentation. Elsewhere, though, he proves he can caress mellow whole tones as easily as succinct sharp breaths.

Schlippenbach’s on-and-off introduction of foreign objects onto his strings alternately produces harpsichord echoes or the rattle and clank that would result if an aluminum pie plate was thrown along the bottom board. This shows that he appreciate the Portuguese challenger’s style.

So plainly did Kowald, for the veteran bassist exhibits a whole bag full of extended tricks and techniques in his meeting with the flautist.

This is most obvious on Parts 9 through 11, as the bassist suddenly unleashes his characteristic vocal drones, expelling a windstorm of sonorous syllables from deep within his chest. When Kowald’s guttural tones mix with Bechegas’ high-pitched verbal squeals the effect can be likened to the soundtrack for a gory, ghost-ridden Japanese horror flick.

Polyphonic, modulated bass flute harmonies as well as leaping, tones from a higher-pitched metal woodwind are the reedist’s response to this vocalizing, not to mention Kowald’s creation of sul ponticello and sul tasto tremolo timbres.

Throughout, there are as many jaw-loosening technique exhibitions from each man as on the other CD. Bechegas, for one, manages to produce split tones that divide airy embellishments of acute whistles from buzzing low-toned vibrations. Other times he literally giggles through the metal mouthpiece.

Meanwhile, when he’s not intoning basso drones like a demented and defrocked priest, Kowald is ranging over the bass strings, neck, front and practically on the pegs. He uses shuffle bowing and spiccato as much as flat-picked strums. Other times the flautist’s relaxed respiration is met with concentrated string jerks and giant sweeps that suggest an aural cartoon of Hurricane Ivan’s destructive activity.

Still Open Secrets is a lesser effort compared to Open Speech. For a start, the 13 segments mean that duo’s work is dissipated into smaller, less germane segments than in the piano/flute duet. Secondly, four years earlier, Bechegas — who also dabbles in multimedia and has since concertized with British guitarist Derek Bailey and American bassist William Parker among others — appears to be less sure of himself. Some of his playing seems a bit frantic as if it was essential to exhibit every one of his unique techniques every time he solos.

Nevertheless both these CDs prove that Bechegas is another Portuguese innovator whose name should be added to the growing list of Iberians populating the ranks of world-class improvisers. Investigate either of these CDs — especially Open Speech — and open yourself up to a new flute voice.