Dissimilation and phonological conspiracy in Tenyidie tone

I propose an analysis for tonal alternations at the prefix–stem boundary in Tenyidie, where Mid tones in prefixes and stems dissimilate. I argue that this alternation is driven by the Obligatory Contour Principle (OCP). Sequences of Mid tones are seen elsewhere. I claim that this asymmetry can be solved with recourse to prosodic phonology (Nespor & Vogel 1986/2007), by assuming that stems and suffixes form a prosodic unit where Mid tones fuse to avoid OCP-Mid. But OCP-Mid also triggers dissimilation across the prefix–stem environment due to prosodic boundaries. This is an example of phonological conspiracy (Kisseberth 2011).