### Tuned by Automatic Just Intonation, Orchestrated by Python Codes

This is the latest version of my collection of Bach Chorales, tuned by my automatic just intonation system. This time I pushed the algorithm to be willing to alter the tuning more to seek out ratios that are as small as possible, without compromising the integrity of the composer’s notes. My algorithm for automatic just intonation has a setting that is adjustable to penalize ratios that have large numerators and denominators. It is called the ratio_factor. The higher the ratio_factor, the harder the algorithm works to find the lowest possible ratios in each interval.

The algorithm also tries to minimize the distance from the original 12 tone equal temperament based on another value, called the dist_factor. The lower the distance factor, the more willing the algorithm is to stray from the original pitches. These two can be varied to produce a tuning that has higher propensity for low number ratios while allowing for notes relatively far from the original 12 tone note. This results in more notes that may sound strange, but are made up of lower numbered ratios, and so have more power. I had previously set those values to 1. This version has the ratio_factor set to 2, and the dist_factor set to 0.35. If I used larger ratio_factor or smaller dist_factor, I ended up with notes that are closer to notes other than the ones the composer selected. I can’t allow that.

The orchestration part of the title is the way that I transform chorales from Bach’s St. John Passion into something entirely different. The notes, after adjusting the tuning, are all Bach’s. How those notes are played is up to the aleatoric algorithm that I coded. It tries to keep notes in the same octave for a longer period of time, and use rhythms that are somewhat consistent over each piece. But lots of random things tend to happen. I create many versions, the cherry-pick the best ones for sharing.

Here are the first three in the mix, and a link to a zip file of all 11 pieces.

O Welt, sieh hier dein Leben (O World, see here your Life)

Jesu Leiden, Pein und Tod (Suffering, pain and death of Jesus)

Herzliebster Jesu, was hast du Verbrochen (O Dearest Jesus, how hast Thou offended)

And if you’d like to hear more, here is a link to the 11 pieces in the album: Zip of all the pieces