UC Santa Barbara

This dissertation investigates the phonetic and phonological behavior of central vowels—particularly non-low vowels such as [ə], [ɨ], and [ɘ]—through a cross-linguistic typological study. Central vowels have long been treated as marginal or anomalous in phonological theory, often grouped under the category of “reduced vowels.” However, their unique articulatory, acoustic, and prosodic properties challenge such simplifications. Schwa, for instance, has been widely described as an underspecified vowel prone to reduction, deletion, and contextual assimilation. Yet, not all central vowels exhibit the same degree of instability, and in some languages they behave as full-fledged phonological segments, able to bear stress, contribute to minimal word constraints, and appear in structurally prominent positions.Building on data from over 150 languages, this dissertation explores how central vowels pattern with respect to stress, moraicity, positional restrictions, and word minimality. Drawing from theoretical frameworks including Moraic Theory and Articulatory Phonology, the study identifies robust asymmetries between central and peripheral vowels, as well as among different types of central vowels themselves. A key finding is that high-central vowels such as [ɨ] tend to behave as more sonorous and prosodically active than mid-central vowels like schwa, supporting a revised vowel sonority hierarchy in which [ɨ] outranks [ə].This research also addresses the phonological representation of central vowels across languages, considering whether they are underlying, epenthetic, or reductional in origin. Special attention is given to cases where multiple central vowels coexist within a single system, offering new insights into the typology of moraic structure and vowel contrast. Additionally, the dissertation highlights regional and areal patterns, such as the relative prevalence of high central vowels in Amazonian languages.By integrating phonetic evidence, phonological theory, and cross-linguistic typology, this dissertation advances our understanding of the central vowel space. It argues that central vowels are not merely articulatory defaults, but often play contrastive and privileged roles within phonological systems. Ultimately, this work offers a framework for rethinking the organization of vowel inventories and challenges traditional assumptions about the marginal status of central vowels. It further proposes that peripherality, rather than height, may be the primary feature shaping the vowel sonority hierarchy.