Tongue displacement and durational characteristics of normal and disordered Brazilian Portuguese liquids
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The goal of the present study was to characterize normal and disordered Brazilian Portuguese liquids. The research hypotheses were that disordered liquid sounds would be characterized by (1) longer syllable and segment durations, (2) larger and more undifferentiated displacement of the tongue and (3) that the speech errors would show sub-phonemic differences depending on the target sound. The participants of this study were 11 children with phonological disorders and 9 control participants matched for age and educational background. The children's tongue movement in the sagittal plane was recorded with ultrasound. The speech stimuli consisted of 3 repetitions of 5 words representing the four Brazilian Portuguese liquids /l/, /?/, /?/ and /?/ in the context of the vowel /a/. A panel of four listeners transcribed each of the productions and classified them as correct or incorrect. The outcome measures were based on duration (syllable duration, ratio L/V) and tongue displacement (percentage average displacement, anterior displacement, posterior displacement). Based on mixed model analyses of variance, the first research hypothesis was confirmed for the /l/ and /?/ targets, but not for the /?/ and /?/ targets. The second hypothesis was partially confirmed. The third hypothesis was confirmed. The research serves to illustrate the effects of phonological disorder on the phonetic realisation of Brazilian Portuguese liquid sounds.