On the concept of Raga parentage in Carnatic music

Abstract

The concept of rāga in Carnatic music is based on an ordered set of notes in an octave. Historically rāgas are broadly classified into two sets, namely Janaka (root/parent) and Janya (derived/offspring) rāgas. Every janya rāga is derived from a unique parent. We examine this classification critically and attempt to provide a quantitative basis for such a classification by defining a ‘distance’ between rāgas. The shortest identifies the parentage. Each rāga is defined by a pitch histogram vector in a 12-dimensional space. To achieve consensus, different distance metrics are used in the multi-dimensional space. Using a standard data set (refer to section 4.4), we carry out the distance analysis using entire compositions, which we subsequently fine-tune using only the parts of compositions that contain all the features of the rāga. We also perform an independent analysis for comparing the motif sequences in rāgas. We find that while the conventional method (refer to section 3) is fairly robust, there are exceptions, especially with pentatonic rāgas, and that these exceptions are actively debated in the public domain. Since quantitative methods find it difficult to achieve consensus, we conclude that while a rāga belongs to a family, it does not necessarily belong to a unique parent.