The reason because of which Indian music sounds exotic to the western listener are the different tuning and scales. The term Indian Classical Music encompasses two individual but related traditions. The Northern Indian tradition is called the Hindustani tradition. The Southern Indian tradition is called Carnatic. (As with many Indian words, there are a variety of spellings in common usage in English, including Karnatak and Karnatik.) Both traditions demonstrate a parallel approach to music and music theory, but the terms used are often different. For instance, where the Hindustani tradition has thaat, the Carnatic has mela. The following discussion focuses on the Hindustani tradition, as it is more familiar to the rest of the world.
Thaat: Classifying Ragas into Families
To create more interest, a raga is often generated by dropping certain notes of a that, where a raga consists of five, six or all seven notes of the that. A that can create more than three ragas. To make things more confusing for a novice listener, the two traditions use same names for two completely different ragas. There can often be disagreement even within a tradition as to the name or proper execution of a particular raga. Ragas may be invented, combined, borrowed from other traditions, or dropped from the repertoire, so the tradition itself, including the theory, is in many ways more fluid and more varied than the Western tradition.
It is also important to understand that a raga is not just a collection of the notes that are allowed to be played in a piece of music. There are also rules governing how the notes may be used; for example, the notes used in an ascending scale (aroha) may be different from the notes in a descending scale (avaroha). Some notes will be considered main pitches, the “tonic” or “most consonant” in that raga, while other notes are heard mostly as ornaments or dissonances that need to be resolved to a main note. Particular ornaments or particular note sequences may also be considered typical of a raga. The raga may even affect the tuning of the piece.
Harmonic and melodic rules differ in case of major and minor scales. Indian music is analogous , only difference being it contains many more scale types. Also , the variations are melody based nuances as opposed to harmonic.