Morphological influences on categorical perception of stop voicing in Welsh

Listeners integrate a wide variety of cues when categorizing speech sounds, including lexical, syntactic, semantic and pragmatic information. We investigate the influence of Initial Consonant Mutation, a morphosyntactically-triggered alternation in the modern Celtic languages, on the categorical perception of stop voicing in Welsh. Once sandhi processes, Celtic mutations are now lexically and morphosyntactically triggered; in particular, Welsh Soft Mutation causes word-initial voiceless stops to become voiced when they are preceded by a triggering word or construction. This paper reports the results of a two-alternative forced choice task that tests the hypothesis that Welsh listeners integrate their knowledge of mutation-triggering environments during speech perception, accepting more ambiguous segments as voiced when preceded by a Soft-Mutation-triggering word relative to a non-triggering word. While the results of the experiment demonstrate categorical perception of stop voicing, no robust effect of mutation environment was found. Several hypotheses as to why the predicted result was not found are considered.