Gestalt Contours, Polarity and Construction-specific Phonology in Gaahmg

In this paper, I provide a new type of evidence for sub-tonal features (Yip 1980, 2002; Bao 1999) from the Eastern Sudanic language Gaahmg (Stirtz 2011): Gestalt contour formation where specific morphological categories change the tone of a base word to a falling contour, but with different absolute tone values (High-Mid, Mid-Low, and High-Low) depending on the input tone. I show that the three different Gestalt contours in Gaahmg can be captured succinctly via feature affixation using Register Tier Theory (Snider 1990, 1998, 1999), and that this analysis receives independent support by other general patterns in the morphophonology of the language. Thus, following McPherson (2017) and Meyase (2021), the paper undermines the major objection against tonal feature geometries that they lack broad support in language-specific tonal grammars (Hyman 2010; Clements, Michaud & Patin 2011). By developing a virtually complete tone-affixation analysis of Gaahmg's tonal morphology in Autosegmental Colored Containment Theory (Trommer 2015; Zaleska 2020; Paschen 2021), the paper also provides evidence for the viability of this formalism in the context of the Generalized Nonlinear Affixation (GNA) program to reduce all productive non-concatenative morphology to affixation of partial phonological representations (Bermúdez-Otero 2012).