Contributing to New Musicological Theories with Computational Methods: The Case of Centonization in Arab-Andalusian Music

Arab-Andalusian music was formed in the medieval Islamic territories of Iberian Peninsula, drawing on local traditions and assuming Arabic influences. The expert performer and researcher of the Moroccan tradition of this music, Amin Chaachoo, is developing a theory, whose last formulation was recently published in La Mu-sique Hispano-Arabe, al-Ala (2016), which argues that centonization, a melodic composition technique used in Gregorian chant, was also utilized for the creation of this repertoire. In this paper we aim to contribute to Chaachoo's theory by means of tf-idf analysis. A highorder n-gram model is applied to a corpus of 149 prescriptive transcriptions of heterophonic recordings, representing each as an unordered multiset of patterns. Computing the tf-idf statistic of each pattern in this corpus provides a means by which we can rank and compare motivic content across nawabāt, distinct musical forms of the tradition. For each nawba, an empirical comparison is made between patterns identified as significant via our approach and those proposed by Chaachoo. Ultimately we observe considerable agreement between the two pattern sets and go further in proposing new, unique and as yet undocumented patterns that occur at least as frequently and with at least as much importance as those in Chaachoo's proposals.