Costa: "Chorale-Etude" in 17edo (on Lumatone Keyboard)

Listen to this in a high-quality audio version at: https://microtonalharmonyproject.band... The division of the octave in 17 equal notes offers the possibility of approaching many overtones with great precision: with it's slightly sharp fifth (3:2) overtones 3 and 9 are still similar to 12 edo - but then 7, 11 and 13 (and further 23, 25 and 27) are also approximated with great precision, much differently than 12edo, which does not. However, the major third 5:4 is poorly approximated in 17edo (it's twice as sharp as in 12 edo). I find it to be a fascinating tuning system which makes a whole new range of tonal harmonies possible - at the same time offering the challenge of restricting the use of the major third, which otherwise reigns absolute in 12edo. "Etude-Chorale" is a harmonic exploration of tonal relations in 17edo, particularly of those partials not availabe in 12 edo: 7, 11 and 13. Since the intervals are equally spaced (it is an equal division of the octave), there are many intervals which have enharmonic equivalences, meaning, they approximate more than one natural ratios, thus allowing for what I like to call "enharmony": the functional ambiguity of intervals having one function in a harmony and another in an adjacent harmony, as common notes to both. This is the principle of this composition. The Keyboard I use is a Lumatone; it has polyphonic aftertouch which I use to modify the timbre and dynamics of the organ- or wind-instrument-like sound produced with Surge XT; the electric piano sound is from Pianoteq.