A percepção de plosivas alveolares na produção de um sujeito com deficiência auditiva: um estudo fonético acústico / The perception of alveolar plosives produced by a hearing-impaired subject: an acoustic phonetic study

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Hearing impairment affects speech production and perception. One of the difficulties the hearing-impaired faces is producing/perceiving the contrast between voiced and voiceless sounds, mainly those which are characterized by a total obstruction between articulators such is the case of plosives, which happen to be one of the highest frequency sounds in Portuguese (Albano, 1995). Among the plosives, the alveolars are specially troublesome since a fine motor control adjustment is required for them to be produced. Such aspects have motivated the carrying out of this research which aims at studying the production and perception of the contrast in alveolar plosives by a hearing-impaired subject. In order to carry out the research a corpus with four dissyllabic paroxytons words (tata, data, cata and cada) inserted in a carrier sentence was build up. The hearing-impaired subject born and living in the city of São Paulo and presenting bilateral neurossensorial hearing loss, characterized as severe on the right side and profound on the left side, developed at eighteen months of age. This work is divided into two parts: a speech production study and a speech perception study. The first part comprised the acoustic phonetic analysis of ten repetitions of the four sentences by means of the software Praat. The duration measures comprised the carrier sentence, the inserted words, the vowel that preceded them and their constituent segments (plosives and vowels). Besides these, the VOT of the plosive segments, the duration of the voicing bar and its interruption within the obstruction time interval, as well as the frequency of f0, F1, F2, F3 of the preceding vowel. The unstressed plosives were also measured. The second part of the study comprised an identification task using two kinds of oral stimuli: the four words inserted in the sixth repetition of the carrier sentence and four manipulated tokens derived from the extraction of the initial plosive of the words. Fifty normal hearing subjects judged the oral stimuli. The comparison between the results of the perception test and the acoustic characteristics of speech production unities of the oral stimuli showed that the percentage of voicing during the obstruction time interval of the plosive was considered the most important factor in identifying the voicing contrast. The results have shown that difficulties in the judgment of the voicing contrast were directly related to varying aspects in the hearing-impaired subjects productions as evidenced by the analysis of the acoustic parameters. This study was based on the Acoustic Theory of Speech Production (Fant, 1960) and Articulatory Phonology (Browman, Goldstein, 1986; 1990; 1992) to analyze the data of speech production from a dynamic perspective

ASSUNTO(S)

linguistica aplicada análise fonético-acústica deficiência auditiva produção de fala

ACESSO AO ARTIGO

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