Articulatory bases of sonority in English liquids

Sonority is generally considered to play a primary role in governing intrasyllabic phonotactics. In this chapter, we examine the phonotactic and articulatory properties of tautosyllabic vowel-liquid sequences in American English, and consider the implications for theories of sonority. Constraints on the distribution of vowels preceding liquid codas were first examined through lexical corpus analysis, revealing that fewer vowel contrasts occur before /ô/ than /l/, with contrasts further reduced before complex codas compared to simple codas. To shed light on these patterns, we investigated liquid production in different syllabic contexts in American English using real-time structural MRI. For each speaker examined, /ô/ showed more stability than /l/ in its lingual posture across contexts. For /l/, the tongue dorsum showed the greatest convergence across different vowel contexts in codas and complex syllable margins. In general, /ô/ exhibited less coronal stricture than /l/, consistent with some phonetic characterizations of sonority, and with traditional sonority-based accounts of the sequencing of /ô/ before /l/ in codas. Yet differences in stricture do not illuminate the observed restrictions on vowel-liquid sequences. Our data point to a greater encroachment on the vowel by a liquid in a complex coda, reducing the potential for contrast in pre-cluster nuclei; furthermore, the greater articulatory flexibility of /l/ renders it compatible with a larger range of vowels than /ô/. We conclude that articulatory factors can have a fundamental influence on phonotactic constraints, and suggest that our understanding of sonority will be enriched by taking into account a wider scope of articulatory properties beyond stricture degree alone.