Knowing the chords in Just Intonation

The contemporary music quartet LOCANA (Janine Grantham - flute; Rachel Westwood - violin; myself - horn; Matthew Farrell - cello rehearsed in Brisbane on Saturday August 18 and Sunday August 19 in preparation for the Sydney MicroFest 2 in Sydney September 22 and 23. We spent a lot of Sunday practising my composition The Wound even without the other 3 musicians who will take part (Wendy Dixon - soprano; Greg van der Struik - trombone; Edwin Diefes - tuba). Although the parts are without notation errors, the players wanted more help to understand the tuning and the way I have notated the tuning. To assist them I have prepared this chord chart today.

What I have found useful for the musicians I work with is to keep the symbols on the staff as standard as possible. To assist, I have indicated the number of cents by which each pitch has deviated from standard 12-division notation (7 white, 5 black on the piano - standard note names plus flats and sharps). I also indicate the position of each note in a chord through coloured note heads.

Black indicates the root of the chord.

Light blue indicates the perfect 5th or major 9th (3rd and 9th harmonics).

Red indicates the major 3rd (5th harmonic) and the rare times I used a minor 3rd from the root of a chord, also the major 7th (15th harmonic).

Dark blue indicates the minor 7th from the root (7th harmonic).

Orange indicates the harmonic series 11th from the root (a quartertone below the augmented fourth).

Purple indicates the harmonic series 13th from the root (a little more than a quartertone lower than the major 6th). I prefer the 11th and 13th to look like they are a minor 3rd apart, rather than an augmented 2nd as is the case when the 13th is notated as a minor 6th (13th) from the root and 41 cents higher. That's why I notate the 13th harmonic interval as a major 6th, -59c.

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