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The effects of perceptual training on the production of English vowel contrasts by Portuguese learners

This study investigated the shortand long-term effects of a high variability perceptual training on the production of three English vowel contrasts (/i//ɪ/; /ɛ/-/ae/; /u/-/ʊ/) by Portuguese learners. The perceptual training consisted of five sessions divided into two blocks that included both discrimination and identification tasks followed by immediate feedback with natural stimuli produced by multiple native talkers in different phonetic contexts. Vowel production data were collected three times, namely before training (pretest), immediately after (posttest), and two months later (delayed posttest) with a sentence-reading task. Both duration and the first two vowel formants were measured to calculate the Euclidian distance (Hz) and duration ratios (ms) between the vowels of the target contrasts. The acoustic analyses revealed that perceptual training had a significant effect on pronunciation accuracy of the target vowels, specifically in terms of vowel quality.