06th Jun 2006
Back in grad school I did a little research on the key distibution of online tunebooks. This was lost for a while, but I recently found the article and graphs buried in my computer.
So to test image tags and floating bodies, here follows a statistical snapshot of Henrik Norbeck’s online tunebook, from about 4 years ago.
If you don’t know ABC notation, I recommend you learn it. It’s a way of notating folk melodies using ordinary text, in a simple and straightforward manner. ABC is human readable/writable, and can be converted to sheet music or MIDI files. Now, I think it’s best to learn tunes from people rather than from paper whenever humanly possible, but as a computer scientist I think ABC notation is just a work of genius. It’s everything a file format needs to be and not a drop more.Anyway, since ABC is text, I can grep it. In particular, I can type
$ cat *.abc | grep "^K:" | sort | uniq -c
…which strips out all the key fields, sorts and counts them, giving me a handy breakdown of the number of tunes in each key. [A slightly more elaborate string of commands is really needed to handle extra annoyances such as capital/lowercase letters, etc.]So, I headed over to Henrik Norbeck’s tune index, a large and very well-formatted collection of traditional tunes in ABC format. Mr. Norbeck provides all the tunes in one big zip file, to boot. So I download and grep.
Enough chit-chat, here are the results:To your left are the tunes sorted by key signature. E.g., A Mixolydian == 2 sharps, corresponding to D major, so all the AMix tunes and Dmaj tunes (and Edor tunes and Baol tunes) are all binned together under “D”.
When the key signatures are arranged on the circle of 5ths, you see a pretty clear bell curve. And look! G and D tunes are pert-near neck-and-neck. G is actually ahead of D by a tiny margin, not what I expected.
To the right is the same data, viewed by tonic (e.g, D major, D minor, D dorian, D neptunian … are all binned under “D”.) Now, D reigns supreme, which is what you’d expect given the standard modes for Irish music.The typical modes of Irish music are Ionian (“major”,) Mixolydian, Aeolian (“minor”) and Dorian (also often called “minor”.) These four modes fall in a row on the circle of 5ths: C major == G mix == D dorian == A aeolian, in the sense that they all have the same key signature. It thus stands to reason that the right half of the graph is going to be bigger, and the left half smaller, when we look at tonics rather than key signatures.
One of the reasons I used Henrik Norbeck’s tune index is that careful attention is paid to both the formatting and the key information. Nowadays, many people just bin mixolydian tunes as “major,” and don’t distinguish between different kinds of “minor” tunes. The distinction matters in Irish music, though, as “minor” very often means dorian, not aeolian.
Here’s both together:
And if you’re interested in modes, check this out:
No surprise that Ionian (the standard “major” key) is the most common, but check out the minor keys. The big minor key is actually the dorian mode, while the “natural” minor is less common even than mixolydian.
Given the type of instruments used in Irish music, it’s no surprise that the dorian mode is the common one. Consider a whistle, which plays a D scale with room for a few accidentals and a usable range of a couple octaves. This isn’t the only instrument that is geared to a few keys and a few octaves: the melodeon and pipes are similar. With these types of instruments, the dorian minor is much more comfortable because it’s right in the same place, just a note up the scale. If you can flatten a note you can make it an aolian minor, but nevertheless the dorian is the natural choice.