Caracterização dos fones [s] e [ʃ] por meio da análise acústica

Abstract

The typical phonological development and phonological disorders are object of continuous studies in speech area, in order to characterize aspects such as phonemes acquisition, strategies of repairing presents in subjects produtions, articulatory and acoustic characteristics of sounds. In the last aspect, it becomes important, the comparison of speech data of adults and children to verify if the acoustic parameters are similar. Thus, the purpose of this study is to compare, with acoustic analysis, the prodution of [s] and [ʃ] of children with or without phonological disorders and adults, considering the acoustic parameters of duration of fricative noise, cutoff frequency of fricative noise, band of frequencies of stronger fricative noise concentration and formant transition of the following vowel. It was realized comparisons between the 31 subjects` data of speech, which were divided in three groups group of children with typical phonological development (average age of 7,12 (± 0,77)), group of children with phonological disorders (average age of 6,87 ((± 0,74) and group of adults (average age of 23,61 (± 3,445)). These subjects came from the schools of Santa Maria/RS city and from Speech Therapy and Audiology service of Federal University of Santa Maria and realized initial interview, screening and phonological evaluation. Speech data were collected in acoustically treated booth. To acoustic analysis there were used two softwares: Praat and Wavesurfer. To statistical analysis there were compared the group of children with typical phonological development to the group of children with phonological disorders and the group of adults to the group of children with typical phonological development. It was verified that, when some parameters are considered, such as duration of fricative noise and cutoff frequency of fricative noise, the children without phonological disorder productions are statistically equal to adults productions. Sometimes these groups productions are acoustically different, but not perceptually, what can be justified by the neuromaturational process, through which children are passing in the studied age. Yet, it was observed that the children with phonological disorder really performed substitutions of studied phones. An example of that is the case of [s], which was produced like a substitution, presents the same acoustic characteristics of an [s] correctly produced, this is, which represents the phoneme /s/. The parameters more efficient to differentiate [s] and [ʃ] were cutoff frequency of fricative noise and band of frequencies of stronger fricative noise concentration.