Gradient dissimilation in Mongolian: implications for diachrony

This paper explores the implications of 'gradient dissimilation' (Jatteau & Hejná 2016) for the diachronic implementation of long-distance dissimilation (e.g. ChVCh > CVCh). Since dissimilation is usually considered as lexically sporadic, cases where it applies regularly throughout the lexicon should result from lexical diffusion. Against this assumption, we explore the hypothesis that gradient dissimilation may represent the phonetic precursor of completed, regular dissimilatory processes. Such cases might then be reanalysed as Neogrammarian types of change. To assess this question, we gather and analyse new data from Halh Mongolian, a language reported to show gradient dissimilation of the aspiration feature, and compare it to two completed patterns of aspiration dissimilation reconstructed within the Mongolic family: Chahar Mongolian and Monguor. The results suggest that the gradient dissimilation in Halh may represent the phonetic precursor of Chahar, but also that gradient dissimilation may be bidirectional for some speakers. An interesting difference between our Halh Mongolian results and the other patterns of the Mongolic family resides in the behaviour of /s/, which in our data does not pattern as expected with the aspirated stops.