Plínio Almeida Barbosa

Characterisation of rhythmic patterns for text-to-speech synthesis

Abstract This article proposes an alternative rhythmic unit to the syllable: the inter-perceptual-center group (IPCG). This group is delimited by events which can be detected using only acoustic correlates (Pompino-Marschall, 1989). The rhythmic patterns for French are described using this characterisation: we show that realisation of accents is gradual over the trailed accentual group and that this gradual lengthening is needed for perception. A model of repartition of the IPCG duration among its segmental constituents incorporating automatic generation of pauses (emergence and duration) according to speech rate is then described.

From syntax to acoustic duration: A dynamical model of speech rhythm production

This paper presents a speech rhythm production model able to generate segmental acoustic duration from several levels of dynamical coupling between linguistic and production-related subsystems. A probabilistic algorithm for phrase stress assignment accounts for both prominence and constituency prosodic relations by considering the coupling between a dependency-grammar system of markers and constituent-size constraints. This algorithm copes with intra- and inter-speaker prosodic variability. Having as input the position and magnitude of underlying phrase stress, and a set of dynamical control parameters, the model acts at three nested temporal domains to assign segmental duration in Brazilian Portuguese. The modelled V-to-V duration patterns reproduce the patterns found at the surface under several conditions of perturbation. The nature and advantages of the dynamical model of speech rhythm production for simulating natural data are thoroughly discussed.

Generation of Pauses Within the z-score Model

We have previously proposed [BB94] a model for the generation of segmental durations that proceeds in two steps: (1) prediction of the timing of a salient acoustic event per syllable according to phonotactic and syntactic information, and (2) application of a repartition model that determines the duration of each individual segment between these events. This chapter focusses on the repartition model and describes how the initial model has been enriched to account for the emergence of pauses as speech rate is decreased. It describes a perceptual evaluation of the whole model. This evaluation shows that, for the same distribution of prediction errors, a precise timing of these events is perceptually more relevant than a segment-based method aiming at predicting precisely each individual segmental duration.

Syllable-timing in Brazilian Portuguese: uma crítica a Roy Major

This paper reintroduces the discussion about stress-timing in Brazilian Portuguese (BP). It begins by surveying some phonetic and phonological issues raised by the syllable- vs stress-timed dichotomy which culminated with the emergence of the p-center notion. Strict considerations of timing of V-V units and stress groups are taken into account to analyze the long term coupling of two basic oscillators (vowel and stress flow). This coupling allows a two-parameter characterization of language rhythms (coupling strength and speech rate) revealing that BP utterances present a high-degree of syllable-timing. A comparison with other languages, including European Portuguese, is also presented. The results analyzed indicate that Majors arguments for considering Portuguese (sic) as stress-timing are misleading.

A new methodology for comparing speech rhythm structure between utterances: beyond typological approaches

This paper proposes a new methodology for automatically comparing the speech rhythm structure of two utterances. Eleven parameters were automatically extracted from 44 pairs of audiofiles yielding 11-size difference vectors. The parameters include speech rate, duration-related stress group rate, prominence and prosodic boundary strength, f0 peak rate, as well as the coupling strength between underlying syllable and stress group oscillators. The 11-parameter difference vectors were used to infer the perceptual differences identified by a group of 10 listeners who judged the same 44 pairs of audiofiles . The results indicate that duration-related prominence or prosodic boundary rate and speech rate, taken together, predict up to 71 % of the response variance. To a minor extent, prominence/boundary strength mean and non-prominent VV unit rate predict up to 60 % of the response variance when combined with prominence or prosodic boundary rate.

Lexical reorganization in Brazilian Portuguese: An articulatory study

This work, which is couched in the theoretical framework of Articulatory Phonology, deals with the influence of speech rate on the change/variation from antepenultimate stress words into penultimate stress words in Brazilian Portuguese. Both acoustic and articulatory (EMMA) studies were conducted. On the acoustic side, results show different patterns of post-stressed vowel reduction according to the word type. Some words reduced their medial post-stressed vowels more than their final post-stressed vowels, and others reduced their final post-stressed vowels more than their medial post-stressed vowels. On the articulatory side, results show that the coarticulation degree of the post-stressed consonants increases with speech rate. Also, with the use of a measure called proportional consonantal interval (PCI), it was found in measurements of articulation that such measure is influenced by the word type. Three different groups of words were found according to their PCI. These results show how dynamical aspects influenced by speech rate increase are related to the lexical process of change/variation from antepenultimate stress words into penultimate ones.

Diferentes pronúncias em uma língua não sonora? Um estudo da variação na produção de sinais da libras

Research on American Sign Language (ASL) phonetics and phonology has shown that signs are made up of distinctive units (parameters) and that these units can exhibit variation in their concrete manifestation. Little is known about Brazilian Sign Language (Libras) distinctive units and their variation. This study represents a fi rst step toward a better understanding of variation in Libras signs, drawing on the analysis of 60 signs as produced by 12 deaf subjects. The analysis of these productions, elicited through images combined with glosses in Portuguese, not only confirmed the occurrence of variation in the handshape, location, movement, orientation, non-manuals and number of hands across subjects, as observed in spontaneous signing, but also revealed variation in other articulatory aspects such as contact. In addition, this study documents variation within the same subject regarding all parameters analyzed.

Conhecendo melhor a prosódia: aspectos teóricos e metodológicos daquilo que molda nossa enunciação

O trabalho tem a finalidade de apresentar aspectos teoricos emetodologicos da area de prosodia da fala para servir de ponto departida para o pesquisador iniciante. A partir da significacaoplatonica do termo “prosodia” desenvolve as acepcoes ligadas aotermo na pesquisa cientifica contemporânea, apresentando nocoescomo proeminencia, fronteira prosodica, acento frasal, grupoacentual, foco, enfase, entoacao e ritmo. Aspectos metodologicosda area como a montagem de corpora de fala de laboratorio comrelacao com a fala espontânea, a normalizacao da duracao silabicae a diferenciacao da prosodia na producao da prosodia na percepcaoda fala sao discutidos com o fim de apresentar algumas questoesde relevo para a area de pesquisa.

Análise e modelamento dinâmicos da prosódia do português brasileiro

This work presents, from output to input, a dynamical model ofspeech rhythm able to become a model of speech prosody. Themodel is based on coupled-oscillator theory, a class of dynamicalsystems theory that brings temporal variability into language by thebias of speech. From segmental duration to syntax-prosody interface,the model simulates several phonological processes such as secondarystress, variation of the duration patterns undergone by speech rate change,segmental effects conditioned by prosodic structure, compensatoryeffects on duration, and so on. Regularity and structuring are linkedtogether in a principled way from coupling of both speech productionand perception, highlighting the importance of a dynamical cyclicattractor. The model can deal with duration perturbation as a resultof paralinguistic information or speech pathology.

A pausa na produção da fala com comprometimento neurológico

Dysarthria is associated with a deficit in phonemic planning orparalysis of specific speech articulators, besides a frequentvelopharyngeal impairment and expected prosodic alterations. Themain goal of this work is to describe the speech rhythm of a userof a palatal lift protheses by analyzing the way she signals somelinguistic boundaries when reading a short story. Pause durationswere measured and pauses were classified into six syntacticcategories. The correlation coefficient between categories anddurations is 62%, signaling that not all variance can be solelyexplained by syntax, but also by considering prosody as the interplaybetween linguistic knowledge and constraints of a biomechanicalsystem. Despite her neuromotor impairment, the subject is able touse pauses to signal a prosodic hierarchy.