Classical Convert

Spiral Tonality

Evening all.

One nice feature of having a decent collection of blog posts up and active is that every now and then someone leaves you a nice comment on a piece you had pretty much forgotten about. Today this was a comment from chaika, who commented on this post back from the depths of last year in which I really, really wanted a piece of software which would automatically display the tonality of a piece of music as it progresses.

Miss/Mister commenter provided me an excellent lead on the subject: Elaine Chew at USC has published a bunch of papers which attempt to do exactly that. Not only are her papers relevant, but via her references I can now work out all the other important writings on the subject. Awesome.

So far it seems that her method for determining tonality is based on a spiral:

In which each point on the spiral is a major fifth higher than the last (and so each point vertically above ends up being a third higher, which is why those chords look like triangles, because it’s a point connected to a spiral-neighbor and a vertical-neighbor) That spiral looks kinda complicated, I know, and I’m feeling the pain a bit because I only know the most basic music theory. However, I’m fairly determined to get to grips with the ideas in this paper, and it’s actually a rather interesting (and effective) way to learn the theory for me: backward from the math.