All forms of music in the world have two essential components – pitch and rhythm. Music is incomplete without the presence of pitches and durations. In Indian Classical music too, these two elements are most essential in theory.
Indian Music is even more specific regarding the pitch, also called the sur or the swara. In Indian music, different intonations of the same note are used when sung in different ragas. Since the tonic doesn’t change, it is easy to establish greater consonance between the pitches. Let us look at how an octave is described in Indian theory.
1. Indian music is based on relative pitch; which means that there are no modulations. Everything in music happens on the basis of one tonic, and keys aren’t changed in the middle of a piece. This tonic is called Sa or Shadj. Every other tone in the octave is established on the basis of this Sa. There can be no Raga which omits this note. It is always an important note, irrespective of what is being sung.
On a C, it looks like this:
सा रे ग म प ध नि सा
2. The basic scale in Indian music is the Natural scale. There are said to be 7 Natural tones, and 5 modified tones or accidentals. Thus there are 12 total tones in Indian Music.
Sa, Re, Ga, Ma, Pa, Dha, Ni.
They have longer names as: Shadj, Rishabh, Gandhar, Madhyam, Pancham, Dhaiwat, Nishad.
Out of these, the tonic and the P5 (Pa) are fixed. The remaining 5 also occur in altered forms.
The notes, Re (2nd), Ga (3rd), Dha (6th), and Ni (7th) have a Flat or Komal form.
They also appear as Komal Re (Flat 2), Komal Ga (Flat 3rd), Komal Dha (Flat 6th), and Komal Ni (Flat 7th).
The note of Ma (P4) also has a sharp or Teevra form.
Teevra Ma is the same as an augmented fourth or a diminished fifth (Tritone).
The tonic and the dominant, however, cannot be altered in Indian music.
3. The concept of microtones or Shruti is inherent to Indian music. There are 22 microtones in an octave as described in Indian Theory. Shruti, which literally means the smallest division that can be perceived, are essential in further describing the 12 tones of music precisely.
Most ragas use the consonances of the Tonic and M3, Tonic and P4 or Tonic and P5. These tones are 5, 9, and 13 Shrutis away from each other; respectively.
4. Mixing and matching the 12 notes can produce several patterns of sound, but not Ragas. A key element of the Raga form is its ability to communicate a mood or a feeling.
There are some rules for Ragas:
a) There must be at least 5 notes present in a Raga.
b) Altered notes cannot be used one after another in a Raga. eg. Use of m2, M2, m3 in a sequence is prohibited.
c) Sa can never be absent from a Raga (the tonic)
d) Either a fourth or a fifth have to be present in every raga.