The process by which new melas were discovered was the Modal Shift of Tonic. The tonic note or the adhara shadja was shifted from note to note and when the self-same notes of the original shuddha scale were played with the new notes as shadja, different scales resulted.
It is common knowledge that when Rishabha of Sankarabharanam is taken as Shadja and the same Sankarabharanam svaras played, Kharaharapriya results.
This happens on account of the re-distribution of the intervals amongst the sapta svaras consequent on the shifting of the shadja.
Likewise Sankarabharana’s ga as shadja gives Todi; its ma as shadja gives Kalyani; its pa as shadja gives Harikambhoji; and its dha as shadja gives Natabhairavi and so on.
The chaturdasa murchanas were derived by the process of Modal Shift of Tonic.
Modal shift of tonic is referred to variously as the process of Graha bhedam, sruti bhedam and Graha svara bhedam.
The process of modal shift of tonic can be applied easily to regularly symmetrical ragas like Sankarabharanam, Sriranjani and Mohana. i.e., ragas whose Arohana and Avarohana are exactly alike and possess the same svaras.
It is an axiomatic truth that in this process, a sampurna raga will yield only a sampurna raga; a shadava raga will yield only a shadava raga and an audava raga, only an audava raga.
A few familiar examples are given below:-
|Mohana’s||ri as Shadja results in||Madhyamavati|
|Mohana’s||ga as Shadja results in||Malkauns|
|Mohana’s||pa as Shadja results in||Suddha Saveri|
|Mohana’s||da as Shadja results in|| Udaya ravi Chandrika or|
|Hamsadhwani’s||pa as Shadja results in||Nagaswaravali|
|Nagaswaravali’s||ma as Shadja results in||Hamsadhwani|
|Kiravani’s||ma as Shadja results in||Hemavati|
|Kiravani’s||pa as Shadja results in||Vakulabharanam|
The process of modal shift of tonic when applied to varja ragas will yield many startingly new ragas hitherto not thought of.
Graha bhedam Example: