Contour Analyzer: Computational tool for the analysis of musical contours

Daniel Moreira de Sousa – [email protected]
  Universidade Federal do Rio de Janeiro

In this article it’s presented a review of terms and concept of Michael Friedmann’s (1985) and Marcos Sampaio’s (2012) approaches to analysis of musical contours. The Musical Contour Theory Musical is a formalization of the relations between pitches in a melodic contour by the numerical abstraction of the pitch levels. This principle may also be extended for others field, like duration (rhythmic contour), dynamic, chord density, texture and so on. Based on this framework, the numerical quality of the contours describes the relative position of levels according to some criterion. The levels are numbered from zero (lowest level) up to n-1 (where n is the number of levels in the structure). For example, a contour expressed by < 2 0 1 >, interpreted as a melodic structure, indicates a motive that begins at the higher pitch, falls into the lowest and ends at the intermediate one, without concern about absolute pitches or intervals involved. Friedmann proposes a series of descriptive concepts, applying some mathematical processes on the contour’s numerical representation, to reveal the contour constructive characteristics, inspired on some conceptual tools of Allen Forte’s Set Theory. This methodology exposes some properties of the contour. Among others, the relative direction between adjacent contour elements based on changes of direction, represented by “+” and “-”, as well the index that expresses the sum of this shifts; the predominant direction (ascending, descending or balanced), both linearly (the movement from an element to next) and abstract (pointing a global direction of motion); the interval between the levels of the contour’s elements and its interval vector that expresses all the intervals (adjacent and non-adjacent) of a contour; and the qualitative and quantitative analysis of the interaction between these intervals. Sampaio proposes a tool for comparing contours with different cardinalities through two indices of direction based on the Friedmann’s concepts. The nomenclature of these concepts is confusing, with many different names and acronyms that do not reflect clearly what each one of them refers to. The main goal of the review of term is to simplify the understanding of it by clearer and didactic nomenclature that expresses the hierarchy between some concepts, as those which are directly related. The analysis of the initial bassoon’s theme of the Introduction of Igor Stravinsky’s Rite of Spring demonstrates all the proposed tools by comparing their individual results with the degree of abstraction of it. The analysis can reveal some characteristics of the bassoon’s contour that are imperceptible by hearing or by analyzing the score directly, which implies in a constructive understanding of the contour. The Friedmann’s and Sampaio’s tools may also be used in the compositional process, reflecting choices made by the composer based on a specific profile of the contour, since different contours can exhibit similar or even equal profiles, providing consistency to the musical discourse. Intending to facilitate the implementation of these concepts by a computational applicative, the software ‘Contour Analyzer’ was developed for Windows OS. The operating principle is based on the analysis of data information as well as through MIDI file reading.