Subtext Recordings will drop the latest release from Ellen Arkbro, titled for organ & brass, on April 14.

for organ and brass is comprised of two haunting pieces by the Stockholm-based composer, both of which focus on tuning, intonation, and harmonic modulation. Following Arkbro’s most recent project, a 26-day long piece at the Stockholm Concert Hall, for organ and brass finds Arkbro returning to her studies in Just Intonation—any musical tuning in which the frequencies of notes are related by ratios of small whole numbers—with La Monte Young, Marian Zazeela, and Jung Hee Choi in New York, as well as Marc Sabat in Berlin.

“for organ & brass” was written for the Sherer-Orgel organ in St. Stephen’s Church in Germany—an instrument dating back to 1624—with a specific kind of historical tuning known as meantone temperament, as Arkbro explains: “Hidden within the harmonic framework of the Renaissance organ are intervals and chords that bare a close resemblance to those found in the modalities of traditional blues music. The work can be thought of as a very slow and reduced blues music.”

Alongside the title composition, the release also features “three,” which deploys the same principles of harmonic relativity but removes the organ to sit as an intimate counterpoint to the title piece.

Ahead of the April 14 release, Arkbro and Subtext have offered up a full stream of the stunning “Mountain of Air,” a rework based on the sounding material of “Three.” You can hear the track in full below, with for organ & brass available for pre-order here.