Some instruments or classes of instruments are particularly known for their capacity to create acoustic musique concrète. Think of the low strings—especially the double bass—and their rich overtone structures, stolid materiality and deep resonance, all of which have allowed adventurous performers to explore an expansive and sometimes quite otherworldly palette of sound. Less associated with this type of sound exploration perhaps are the brass instruments. To the extent that this perception holds, Norwegian trombonist Henrik Munkeby Nørstebø is out to challenge it.
Trained in jazz and improvisation at the Gothenburg and Oslo music academies, Nørstebø seems to take a holistic approach to his instrument, one that encompasses its full range of dynamics as well as the different voices available to it. As an instrumental personality, the trombone can be brassy and broad; Nørstebø doesn’t evade this side of it, but he does also manage to elicit a quieter, more abstract side: he reveals the trombone’s secret life as an introvert.
Both sides of the instrument are explored on the first of the album’s two tracks, Sources of Internal Heat, for solo acoustic trombone. Introducing the piece with several long C# notes separated by silences, Nørstebø proceeds to build timbres marked by a low-buzzing, rough flutter, contrasts of register, beats and multiphonics, and dynamic variations. Abstract sounds bordering on the quasi-electronic have a place as well, but so do legato melodic fragments and voice-like microtonal drifts and glissandi.
The second track, Melting into Foreground, brings in the prerecorded sound of Nørstebø on half-clarinet, which is multiplied and overlaid into irregular relationships with itself. Like the first track, this one trades in sonic ambiguities. Sounds of rumbling and static, or apparent birdsong and feedback can sometimes be traced to their sources in the acoustic trombone or in the manipulated recording—and sometimes not. The effect is acousmatic but unmistakably rooted in the recognizably musical.
On both pieces, Nørstebø keeps his compositional structures clear through a balanced use of filled and empty space. The silences he allows between passages of sound tend to act as boundaries separating sections into disjunctive events defined by dramatic changes in timbre as well as in organization and dynamics. And despite his deliberate distorting and dismantling of the trombone’s conventional voice, he allows a fundamental warmth to pervade both performances.