Author: Carter-Enyi, Aaron
Title: Contour Levels: An Abstraction of Pitch Space Based on African Tone Systems
Institution: Ohio State University
Begun: March 2015
Completed: April 2016
Based on data from two years of fieldwork in Nigeria, a new methodology for contour analysis is presented with two motivations: 1) extend contour theory into an applied computational approach appropriate for a wide range of symbolic and recorded music; 2) develop a new discretization of pitch, similar to solmization but without an association to a scale or tonal qualia, that can be used to measure pitch prominence (or markedness) in both music and speech. As an alternative to the conventional contour matrix for a segment of cardinality n which compares pitches at all degrees of adjacency up to n-1, a continuous matrix is introduced, with unspecified cardinality and a fixed number of degrees of adjacency. The continuous matrix is a series of contour slices. Each slice compares a pitch to the pitch before and after up to the degrees of adjacency. The elements in each contour slice (a column in the continuous matrix) can be summed creating a measure of relative pitch height, a contour level. The analysis implementation is based on a relationship between contour recursion and segmentation of pitch series. Thematic unity, as provided by contour recursion, is presumed to be intentional on the part of the producer and salient to the receiver. Non-overlapping iterations of a highly recursive contour are both semiotically and structurally important in a wide variety of monophonic signals. The analysis is made more robust by searching for transformations and using reductive processes that make it possible to compare segments of different cardinalities. Contour level analysis is applied to the phenomenon of “tone-and-tune”, wherein a single pitch series carries both linguistic and musical or paralinguistic communication. First the concept of a toneme (a pitch contrast in speech) is explored. Phoneticians and phonologists have described the toneme with paradigmatic (context-independent) and syntagmatic (context-dependent) features, but neither seems to satisfactorily formalize phonological equivalence of tone. Shortly before he died, prominent linguist Nick Clements asked “Do we need tone features?”, concluding that if we do, the ones we have are not working. A cue is taken from the folk heuristic and widely used pedagogical device for the Yoruba language: Low-Mid-High tones are called Do-Re-Mi. It quickly becomes clear that the comparison with solmization has nothing to do with a tonal system and everything to do with relative pitch. Contour levels are proposed as a formal heuristic for the toneme that captures the relevant pitch relativity of the do-re-mi folk heuristic, while freeing it from the misleading Western tonality association. The rich oral poetry tradition of Southwestern Nigeria is explored using this approach.
Keywords: contour theory, music cognition, Yoruba, Igbo, tone languages, Nigeria, phonology, choral music, popular music, African music