For Sound of Stockholm’s residency at Tyska Kyrkan, Ellen Arkbro will perform her work together with the Berlin based brass trio Zinc & Copper, who specialize in microtonality and has collaborated with C.C. Hennix and Christian Wolff, amongst others. As part of the evening, Robin Hayward will present Alpha Centauri for brass trio.

The star system Alpha Centauri consists of a binary star plus a red dwarf. It provides a perfect analogy for the underlying harmonic structure of the piece, in which consecutive dyads (two tones sounding simultaneously) trace a rotating path through harmonic space, whilst a third tone induces a continually shifting perspective. The dyads are based on the 11th and 13th harmonics, opening up neutral (neither minor nor major) intervals such as the 11:9 and 16:13, along with the flat minor third 13:11. It may be the influence of such harmonies, which could not be more remote from the conventional equal tempered tuning of the piano keyboard, that lend the piece a certain floating, dreamy quality. The piece was composed and rehearsed using the Hayward Tuning Vine software interface for Just Intonation.