Ponderação de pistas auditivas por crianças e adultos falantes nativos do português brasileiro

Abstract

Objective: This study investigated the developmental changes in cue weighting for thedistinction of voiceless coronal fricatives ([] and [s]) and of bilabial and alveolar stops ([b]and [d]) in Brazilian Portuguese. The main hypothesis tested was that children weight thedynamic cues more than adults, whereas adults used more the static cues (Nittrouer,Manning & Meyer, 1993). Methodology: The sampling was constituted of children of agesfour and seven years old, as well as adults. Twelve subjects were tested in each of the threeage groups. Both children and adults were recruited from two education centers and from agovernment institution in Belo Horizonte/MG. For each words pair investigated, amongthem /apa/-/sapa/, /aba/-/saba/ and /bata/-/data/, two synthesised continua were produced.Two auditory cues were manipulated: one cue was manipulated identically in both continuaand the other cue was manipulated differently in the two continuums. The participantsperformed a classification task in which they heard the stimuli on headphones and decidedwhich category was the most coherent to what had been presented among the existingpossibilities. Results: The data gathered was statistically analyzed using the probit model,the analysis of variance (ANOVA) and the multivariate analysis of variance (MANOVA)for the fricatives and the paired t-test for the plosives. The results revealed that for theminimal pair /apa/-/sapa/ and for the nonword pair /aba/-/saba/, adults and seven-year-oldchildren weighted the static cue of centre frequency of the frication noise more heavily thanthe younger children. However, none of the three age groups was more influenced by thedynamic cue of formants transition. In addition, there was a change in the responses patternof the three age groups for the classification of words and nonwords, indicating an effect ofthe lexical status. For the words pair /bata/-/data/, composed by stops, the four-year-oldchildren weighted more heavily the dynamic cue of formants transition than seven-year-oldchildren and the adults. Still in this pair, the static cue of burst amplitudes wasntsignificantly weighted by any age group. As expected, in all word pairs, younger childrenshowed more inconsistent and categorical less response pattern with shallower classificationcurves, in which was observed a change in responses pattern throughout the development ofthe child. Conclusions: From the results it can be concluded that younger children have notalways weight more heavily the dynamic cue than the adults. It was also concluded that thestrategies of cue weighting seem to modify according to: a) the child's experience with hisnative language; b) the phonological contrast tested; and c) the informativeness that theauditory cues provide to the listeners for the classification of the contrasts.