From Carillo to Vïshnegradsky, from Partch to Young, there exists a counter-tradition of composers who have sought in free intonation and microtonality a quasi-utopian escape from what they view as centuries of oppression by the fudge of equal temperament. Berlin-based Catherine Lamb, a former student of James Tenney, is a new voice in this line.

In recent years Lamb has devised a system of notation based on frequency ratios, using in-depth harmonic thinking to create what at times come across less as simple compositions than as extended sonorous events or even quasi-ecological harmonic environments. While this technical approach might make it difficult to compose music that’s playable by mainstream ensembles, it also means striking up lasting performer-composer relationships with those who specialise in non-standard tunings.

Muto infinitas (2016/18) is an hour-long duo for quartertone bass flute and double bass. Rhythm, pulsation and articulation are largely abandoned in favour of senza vibrato pitches held for a very long time. Overlaps between the two instrumental voices alternate with solo tones held by one or the other, which can then function as pivots into new harmonic areas. There are aspects of La Monte Young here (The Second Dream …) and of Morton Feldman but Lamb’s voice is very much her own, transcending these references. Perception starts with the sound’s pitch identity before becoming aware of its grainy materiality. What one might at first suspect to be overly austere on the contrary effects in the listener deep emotional resonance. Different harmonic areas, dwelt on for extended periods of time – so long that the music becomes something you bond with – affect us in unpredictable ways. As when you sit for an hour before a Rothko, memories and images can begin to appear in your mind’s eye.

Over the duration of Muto infinitas, the harmonic character and tessitura very gradually develop, giving a sense of narrative arc. Performers Rebecca Lane (flute) and Jon Heilbron (bass) show precision, concentration and sympathy in this performance.