Integrating production and perception of secundary prominences in a dynamical perspective of rhythm / Integrando produção e percepção de proeminencias secundarias numa abordagem dinamica do ritmo da fala
AUTOR(ES)
Pablo Arantes
DATA DE PUBLICAÇÃO
2010
RESUMO
The thesis investigates two main subjects: secondary stress in Brazilian Portuguese (BP) and the link between rhythm production and rhythm perception. Both subject matters are developed in light of Barbosa s (2006, 2007) coupled-oscillator model of rhythm production. Interest in secondary stress in BP is fostered by the fact that its existence, nature and distribution patterns are disputed in the literature. Also, the few existing experimental data do not help to settle the issues. Two production experiments are reported that aimed at describing the patterns of acoustical parameters traditionally considered correlates of stress observed in target words with at least two prestressed syllables. The experiments corpora manipulated target word variables such as the number of prestressed syllables, syntactic position and referential status. Duration, fundamental frequency, vowel quality and spectral emphasis were measured. Results suggest that there s evidence of optional and speaker dependent initial prominence marking. Lengthening of utterance-initial syllable-sized units and fundamental frequency peaks also aligned to initial syllables are the main correlates of initial prominence. The number of target words prestressed syllables has the strongest influence in initial prominence marking among the variables manipulated in the corpora. Simulations run with the coupled-oscillator model indicate that it is able to generate patterns of initial lengthening similar to the ones observed in the experiment. We outlined a proposal for a unified approach to speech rhythm that extends the notion of coupling and entrainment to the speaker-hearer relationship. Two perception experiments were run to test the implicit proposition that rhythm perception is the result of listeners getting entrained by speaker s produced timing. In the experiment, clicks were inserted near each vowel onset along two consecutive stress groups in test sentences. Each test sentence had one click and there were as many test sentence copies as vowel onset in the two stress groups. Subjects were instructed to press a button as soon as they heard the click upon listening to test sentences. Results show that the closer the click is to the stress group boundary (signaled in the speech signal by a peak in normalized duration) the faster the RT is. The crucial result concerning the speaker-hearer entrainment hypothesis, though, is that RT slows down after the stress group boundary, resuming its decrease afterwards, suggesting that the listener is sensitive to the effects of the boundary on the temporal structure of the signal being heard. Regression analysis points out that previous intervocalic interval duration (relative to the interval the click is associated to) and the derivative of the median fundamental frequency over the intervocalic interval account for nearly 50% of the variance in detection latency times. Overall the results seem to provide initial evidence to the speaker-listener entrainment hypothesis by showing that important events in the speech signal like a boundary have an impact on listeners flow of attention along the sentence. Also, results single out the importance of vowel onsets as a carrier of prosodic structure and its role as a common currency between production and perception
ASSUNTO(S)
lingua portuguesa - acentos e acentuação brazilian portuguese phonetics fonetica lingua portuguesa - ritmo lingua portuguesa - brasil percepção da fala portuguese language brazilian portuguese speech perception
