I had these images of the chromatic scale as a ring with twelve circles spinning in my head this week. For the uninitiated, the chromatic scale consists of twelve notes in every octave. Subsets of these notes produce scales that are familiar to many. Where was I? Yes, the image of the chromatic scale as a ring helped me see something that I had completely missed, and I wanted to blog about it. Anyway, I am getting ahead of myself.
Let’s start at the very beginning: a very good place to start. The major scale (Do Re Mi Fa So La Ti) consists of seven of the twelve notes, with a rigid ordering relative to a root note selected from the chromatic scale. This ordering gets repeated in every octave, so it is convenient to draw the notes as a ring. As an example, if the root note is C, the notes in the major scale are the black circles in Figure 1. From the figure, one can see that the notes in this scale are either one chromatic note (a half step) or two chromatic notes (a whole step) apart.
What about Indian classical music? Again, we can have up to seven notes (Sa Re Ga Ma Pa Da Ni) from the chromatic scale, for a total of seventy-two scales when all seven notes are used. Each scale is typically referred to as a raagam (or raaga, depending on where you’re from). For every raagam, the positions of Sa, the root note, and Pa are always fixed, where the raagam’s name corresponds to the position of the other notes. If we let Sa correspond to C, we get the image depicted in Figure 2.
Figure 2 also shows Mohana Raagam, which can be used to play some simple geethams and is also a pretty easy scale on which to improvise. Almost any random ordering of notes manages to sound good, so you can trick people into thinking you know what you’re doing. It’s like keeping the six strings on a guitar open (E A D G B E) and just strumming.
Now here’s the kicker. Suppose we switch from the C major scale, where C is the root note, to the G major scale. This simply requires shifting the black circles in Figure 1 counterclockwise by five notes, so that the black circle previously at C is now at G. We can perform the same operation on Mohana Raagam from Figure 2. This leads to Figure 3, and looking at Mohana Raagam on the bottom, its notes correspond to E, A, D, G, and B, the same as the strings on a guitar!