Metaphony and umlaut are well-studied assimilations, and metaphony, in particular, has attracted a range of different analyses. This article casts both in the framework of Element Theory, but as quite distinct processes. We then study the complex assimilation pattern of the Khoisan language ǃXóõ, between the first vowel of its bimoraic words and the second vowel, also affected by the consonants in the word. The most recent analysis, by Lionnet, argues that probabilistic and cumulative gradient effects are required to account for this process. We show that the process can be seen as formally a combination of umlaut and metaphony. Moreover, our analysis explains other assimilations and predicts a new assimilation, which is confirmed by recent data.

Metaphony provides a unique window into the nature of the capacities of phonological grammars. The representational issues metaphonic processes highlight are exactly those core to computational analysis. Prominent examples of such processes, under various systems of phonological and morphological representation, are examined using algebraic methods, which describe the structure that arises when certain sequences exhibit the same behaviours. This analysis clarifies how representational choices interact with computational complexity. In particular, the simplest characterisations are obtained when the patterns are analysed at the syllabic level, as opposed to the segmental level, and when distinct morphemes are not demarcated by morpheme boundaries but by morphologically marked phonological material. Furthermore, these analyses speak directly to issues in learning, acquisition, production and perception.