From hiatus to diphthong: The evolution of vowel sequences in Romance

Romance languages show hiatus and diphthongal realisations of inherited iV sequences of rising sonority (e.g. ia). We study five Romance varieties with different degrees of contrast between the two realisation types: Romanian, with a diphthong-hiatus contrast, Spanish, with a weaker contrast, French, with no contrast (all diphthongs), and European and Brazilian Portuguese, with no contrast (all hiatus). We show that the different degrees of synchronic contrast are related to three independent factors: (i) a general articulatory tendency for [iV] hiatus to resolve to diphthongs, due to the relative stability of diphthongal articulations; (ii) a structural 'attractor' effect of pre-existing [jV] diphthongs in a language, from different historical sources; and (iii) prosodic lengthening effects which inhibit the shift from hiatus to diphthong, supported by phonetic studies of durational patterns across the five languages.