Influence of the European Portuguese phonological system on the perception of close-mid and open-mid vowels

Abstract

This study's purpose was to analyse the influence of neutralisation on the perception of European Portuguese (EP) close-mid and open-mid vowels, and the gradient between the /i/, /e/, /ε/ and /a/ phonological categories. A fuzzy boundary between mid-vowels has been described in the phonological systems of various languages including EP, a variety of Portuguese with complex phonological phenomena and exceptional realisations of vowels in different contexts. Fifteen listeners from Lisbon participated in two tasks: Identification and goodness rating of 20 random repetitions of 31 stimuli from a /i/-/e/-/ε/-/a/ continuum. The boundaries between categories in the identification task, the internal structures of each category and the gradient of each boundary in the goodness rating task were analysed. Logistic regression was used to analyse the individual responses of listeners and the internal structure of phonemic categories, and prototypes were determined using bubble charts of goodness scores. The gradient of boundaries was analysed using two sets of data: X responses and goodness ratings. Models of the gradients of transition were developed using a mixed effects regression approach. Results from the identification task showed four vowel categories marked by three distinct boundaries. The stimulus with the highest score was approximately in the centroid and the goodness score decreased as the stimulus moved away from the centroid, which constitutes new evidence of an internal structure of the phonemic categories in EP. The main implications of the results obtained are for the description and typology of phonological phenomena in EP, supporting the existence of a non-partial contrast (which does not neutralise in any context) between /ε/ and /a/, and revealing less robust /i/-/e/ and /e/-/ε/ phonemic oppositions.