The relationship between the coarticulatory source and effect in sound change: Evidence from Italo-Romance metaphony in the Lausberg area

In ongoing sound changes, a coarticulatory effect is often enhanced as the coarticulatory source that gives rise to it wanes. But quite how phonologisation and these reciprocal coarticulatory changes are connected is still poorly understood. The present study addresses this issue through an acoustic analysis of metaphony, which like umlaut has its phonetic origins in VCV coarticulation, and which was analysed in three geographically proximal varieties spoken in the so-called Lausberg area in Southern Italy. The corpus was of 35 speakers producing mostly disyllabic words with phonetically mid stem vowels and suffix vowels that varied in phonetic height. The results of functional principal components analysis applied to the stem vowels' first two formant frequencies showed a progressively greater enhancement to the vowel stem across the three regions that was characterised by raising, diphthongisation, and then further raising and monophthongisation. Suffix erosion was quantified by counting deletions and the degree of vowel centralisation. The analysis showed a reciprocal relationship between stem enhancement and suffix erosion across, but not within, the three dialects. Overall, the results suggest that a trade-off of cues between suffix and stem vowel has progressed to different degrees between the three varieties.