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Octotonic Scales
"Octo" is Latin for "eight". Octotonic scales consist of eight tones, covering one octave.
This may be confusing! An octotonic scale has eight tones. An octave has a range of eight tones. However, an octotonic scale has eight tones before the "new" octave starts, an octave starts at the eight tone. Looking at an octave, there are twelve semitones in an octave. The octotonic scale uses eight of them.
Not yet confused?
A "normal" major or minor scale has seven tones before a new octave starts. It is however not called a septemic scale (septem is seven in Latin), it is called a diatonic scale. "Diatonic" comes from the Old Greek for "going through tones". So the name origins in an other old language, and has a different meaning.
It's okay to be confused!
The point is that music theory has been developed during many centuries,
there is not always a clear logic!
For now: an octotonic scale has eight tones. That's all you need to know!
In practice there are two ways to build octotonic scales: a sequence of whole-half tones, and a sequence of half-whole tones. We'll start with the first, which is also called ... the diminished scale!
The Diminished Scale, aka Octotonic Whole-Half
Starting at C, you get the following sequence of tones:
This scale contains the same tones as the diminished arpeggio/scale we looked at earlier, plus four extra tones:
This octotonic-whole-half scale can be used to improvise over a diminished chord. The extra tones compared to the diminished arpeggio can be interpreted as lead tones.
This is how the scale sounds:
C Octotonic Whole Half
And this is how it sounds when the extra tones are interpreted as lead tones:
C Octotonic Whole Half (extra tones as lead tones)
