Umlaut and opacity in Uyghur

We utilize phonetic data from an open-access audio corpus to demonstrate that Uyghur Umlaut (e.g. /bɑʃ-I/ ‘head-3.POSS’’ → [biˈʃi]) engages in counterfeeding and counterbleeding interactions with three other cyclic phonological processes in the language, and that two of these (High Vowel Deletion and Low Vowel Raising) are themselves involved in a complex intra- and inter-cyclic opaque relationship. We argue that while Rule-Based Phonology effectively captures the mechanics of this system, several leading approaches to opacity in Optimality Theory, including Stratal OT and OT-CC, face challenges in accounting for these patterns. Furthermore, we suggest that the interaction between High Vowel Deletion and Low Vowel Raising reveals a previously unnoticed challenge for Optimality Theoretic frameworks, particularly in modeling focus counterfeeding opacities that involve deletion or insertion.