This contribution aims to focus on various descriptions and theories of the segmental inventory and distributional constraints of the phonology of Tu'un Savi (Mixtec). The Oto-Manguean languages are reputed to be among the most complex of Meso-America due to the intricacy of their surface forms. Mixtec (known as Tu'un Savi or Ñuu Savi by its speakers) is part of the Mixtecan sub-family, which includes Trique, Cuicatec and probably also Amuzgo (Longacre, 1957, 1961; Longacre & Millon, 1961), belonging to the eastern branch of the Oto-Manguean family of languages. Varieties of Mixtec offer up such degrees of differentiation that we are tempted to see Mixtec as a further sub-family of Mixtecan rather than simply posit dialectal variation within a single language. Using the work of Josserand (1983) on the dialectal network of Mixtec along with a database combining etymons and a selection of cognate lists from Longacre (1957), Bradley & Josserand (1982), Josserand (1983), and Dürr (1987), we propose a revision of the data through the eyes of the more modern phonological theory of Feature Geometry, enabling us to reach a certain number of conclusions concerning the complexity of the phonological inventory of the modern Mixtec languages. Feature Geometry (Clements 1985; Clements & Hume 1996) is a model for phonological typology aiming to simplify the structure of phonological categories into natural classes and features subject to hierarchical relations and interactions. It allows us to understand and describe what appears to be a high degree of diversification in languages via a limited set of parameters. Without entering into a debate on exactly which parameters should form this set and exactly how they should be organized, we intend to demonstrate in this paper how a system of apparent great phonological complexity, such as that of Mixtec, benefits from a Feature Geometry analysis, revealing a simplified, coordinated set of modules with relations of (a)symmetry of variable geometry. We will try to define how a complicated system with features of sonority and of tension, along with glottal, nasal, and labial features can be simplified and redefined; from the consonant system of 21 phonemes reported in the literature for a particular variant of Tu'un Savi (Peñoles Mixtec, Mixteca Alta, Suárez 1983: 38), we will recover only seven (or eight) underlying categories. This approach would like to bring to the forefront the value and possibilities of a theory such as Feature Geometry, and the importance of the simplicity/complexity of phonological inventories for typology. The Oto-Manguean languages happens to be a privileged observatory, contributing to the understanding of the world's languages.
