lthough many political observers are preoccupied with Norwegian oil and what changes these reserves have brought to that country, when it comes to improvised music, brass is a more appreciated commodity. That’s in part due to Trondheim-born tuba player Martin Taxt who has initiated unique roles for his elephantine tone-inflected instrument. He’s moved beyond orchestral and Jazz coloration – or rhythmic bass functions – to collaborate with noise and electronic experimenters, other instrumentalists and even singers.

Another role involves intersection with others who expose a multiplicity of timbres available from these instruments, as does as part of the Microtub tuba trio with fellow Norwegian Peder Simonsen and British microtonal tuba exponent Berlin-based Robin Hayward. Bite of the Orange, recorded in Italy in late January 2016, is the band’s third CD. Ranging farther afield into the noise/processing/electronic interface, hjem was recorded in Moscow five months earlier. Here Taxt improvising alongside local Kurt Liedwart generating sine waves from his ppooll program, and Saint Petersburg’s Andrey Popovskiy whose sound sources are violin, electronics and objects. Each CD is less than one-half hour in length.

Brevity is the soul of wit is one overused cliché, but the germ of truth in that is never more obvious than with these CDs. During the single track which makes up the Russian-recorded disc, careful attention can be paid to the nuanced broken-octave connections among three tonal outputs. At first, continuous tuba lowing is obviously outlined against the oscillating electronics and abrasively scraped objects from Liedwart, which stand out like descending icicles on a snow bank. Soon however, as shrill violin-string plucks and granular synthesis from the ppooll become more prominent, nearly translucent sound overlays the interaction, creating a nearly opaque squirming mass. Eventually though as noises resembling the grinding of gears become aurally obvious and Taxt’s inner-tube-like blows become shriller, the narrative is divided between alpine meadow-elevated and recessed coal mine-low timbres. For extra drama, clock-like ticking is heard in the silences behind blowing as if the improvisation is counting down to a climax. Finally the apex is reached as static and wave forms quiet to reveal what sounds like receding footfalls.

Should hjem be described as aural sfumato, overlaying sound layers with no perceptible transition among them, than Bite of the Orange could be defined with another term from the visual arts. Grisaille, which is decorations in a single color that produce a three-dimensional effect, is essentially the result of harmonizing three instruments that on the surface are as indistinguishable as eggs. Although Simonsen and Taxt play microtonal C-tubas and Hayward a microtonal F-tuba, microtonal is the key adjective here because Hayward has researched and created these microtonal prototypes so that more timbres can be used by the brass players.

This album isn’t anything like an auditory laboratory report. Yet as early as the first track, while the harmonized three appear to output the same squirting tones, the finale involve the subtle segregation between bottom-of-the-sea-like pitches and elevated treetop-like tones, with the brass connection continuously dissolving or stalling. Finally, during “Violet Man”, a Hayward composition like the title track, the three reach a point if discordant romanticism. Although connections evolve at tortoise-like speed, the leisurely pace allows the trio to bask in the luxuriously balanced melody. The ending arrives when quivering tones connect briefly, and then rapidly disappear. Not designed for languid or cozy listening, these CDs should impress low-brass fanciers and anyone interested in unconventional, 21st Century musical connections.