The perception of stop consonants by children

Subsegmental representation in child speech production: structured variability of stop consonant voice onset time in American English and Cantonese

Voice onset time (VOT) of aspirated stop consonants is marked by variability and systematicity in adult speech production. The present study investigated variability and systematicity of voiceless aspirated stop VOT from 161 two- to five-year-old talkers of American English and Cantonese. Overall, many aspects of child VOT productions parallel adult patterns, the analysis of which can help inform our understanding of early speech production. For instance, VOT means were comparable between children and adults, despite greater variability. Further, across children in both languages, talker-specific VOT means were strongly correlated between [th] and [kh]. This correlation may reflect a constraint of "target uniformity" that minimizes variation in the phonetic realization of a shared distinctive feature. Therefore findings suggest that target uniformity is not merely a product of a mature grammar, but may instead shape speech production representations in children as young as two years of age.

Contextual Influences on Phonetic Categorization in School-Aged Children

Perceptual stability in adult listeners is supported by the ability to process acoustic-phonetic variation categorically and dynamically adjust category boundaries given systematic contextual influences. The current study examined the developmental trajectory of such flexibility. Adults and school-aged children (5-10 years of age) made voicing identification decisions to voice-onset-time (VOT) continua that differed in speaking rate and place of articulation. The results showed that both populations were sensitive to contextual influences; the voicing boundary was located at a longer VOT for the slow compared to the fast speaking rate continuum and for the velar compared to the labial continuum, and the magnitude of the displacement was slighter greater for the adults compared to the children. Moreover, the two populations differed in terms of the absolute location of the voicing boundaries and the categorization slopes, with slopes becoming more categorical as age increased. These results demonstrate that sensitivity to contextual influences on speech perception emerges early in development, but mature perceptual tuning requires extended experience.

Estudo sobre a percepção e a produção do contraste de vozeamento da fala de crianças de 3 anos

OBJETIVO: apresentar um estudo da percepção auditiva que o adulto tem sobre as características das plosivas vozeadas e não-vozeadas em posição acentual tônica e pós-tônica produzidas por crianças de três anos. MÉTODOS: inspeção fonética-acústica das características encontradas na produção das plosivas, quanto ao intervalo de obstrução, do burst, e análise quantitativa das medidas do Voice Onset Time das seis plosivas do Português Brasileiro (PB), em frases-veículo "Diga ________ baixinho" por quatro crianças da faixa etária dos três anos, três meninos e uma menina, falantes nativos do PB, com análise em espectrograma de banda larga no programa Praat. Posteriormente, submissão a 120 sujeitos adultos do corpus produzido pelas crianças, por meio de um teste de percepção, do tipo identificação. RESULTADOS: encontradas na produção, características incomuns à fala do adulto, tanto para as vozeadas como as não-vozeadas. O teste revelou que os juízes perceberam as plosivas não-vozeadas como vozeadas pela presença de breathy vowel. As plosivas vozeadas sempre foram identificadas como vozeadas. O ponto articulatório, das plosivas bilabiais, alveolares e velares não interferiu no julgamento das plosivas. O teste ANOVA (sig= 0,05) revelou que as plosivas foram identificadas corretamente quando apresentavam a presença de breathy vowel ou de barra de sonoridade com mais de 60% de vozeamento. A presença de aspiração não interferiu no julgamento das plosivas não-vozeadas. CONCLUSÃO: resultados indicaram que ocorreram dificuldades na sincronização entre o gesto glotal e o articulatório, que não interferiram na percepção desses sons, uma vez que as plosivas não-vozeadas que apresentaram aspiração foram corretamente avaliadas como não-vozeadas.

Language-experience facilitates discrimination of /d-/ in monolingual and bilingual acquisition of English

To trace how age and language experience shape the discrimination of native and non-native phonetic contrasts, we compared 4-year-olds learning either English or French or both and simultaneous bilingual adults on their ability to discriminate the English /d-th/ contrast. Findings show that the ability to discriminate the native English contrast improved with age. However, in the absence of experience with this contrast, discrimination of French children and adults remained unchanged during development. Furthermore, although simultaneous bilingual and monolingual English adults were comparable, children exposed to both English and French were poorer at discriminating this contrast when compared to monolingual English-learning 4-year-olds. Thus, language experience facilitates perception of the English /d-th/ contrast and this facilitation occurs later in development when English and French are acquired simultaneously. The difference between bilingual and monolingual acquisition has implications for language organization in children with simultaneous exposure.

Developmental trends in voice onset time: some evidence for sex differences

This study reports on an investigation into the voice onset time (VOT) patterns of the plosives /p b t d/ in a group of 30 children aged 7 (n = 10), 9 (n = 10) and 11 (n = 10) years. Equal numbers of girls and boys participated in the study. Each child named a series of letter objects to elicit /p b t d/ in a syllable onset position with a fixed vowel context. VOT data were examined for age, sex and plosive differences with the following hypotheses: Firstly, that there would be sex differences in the VOT patterns of preadolescent children. Secondly, that the sex differences in VOT patterns would be linked to age and development, and that these would eventually become marked by the age of 11 years, by which time adult-like VOT values should have been achieved. Finally, that the extent of sex and age differences would be dependent upon the plosive being investigated. Results indicated patterns of decrease with age in the VOT values of /p b/ for the boys, with some evidence of increases in the VOT values of /t/ for the girls. In addition, 'voiced' and 'voiceless' cognates showed a more marked bimodal distribution in the girls' VOT patterns. This bimodal distribution was investigated by examining the degree of difference between the VOT values of voiced and voiceless cognate pairs /p b/ and /t d/, and examining the effects of age, sex and cognate pair. These results indicated that more marked sex differences in the 'voiced'/'voiceless' contrast emerged between the data of the 9- and 11-year-olds, a pattern, which was more marked for the alveolar plosives. These preliminary results confirmed all three hypotheses. The findings are presented and discussed both within a developmental and sociophonetic framework.

Trading relations in the perception of speech by 5-year-old children

Five-year-old children were tested for perceptual trading relations between a temporal cue (silence duration) and a spectral cue (F1 onset frequency) for the "say-stay" distinction. Identification functions were obtained for two synthetic "say-stay" continua, each containing systematic variations in the amount of silence following the /s/ noise. In one continuum, the vocalic portion had a lower F1 onset than in the other continuum. Children showed a smaller trading relation than has been found with adults. They did not differ from adults, however, in their perception of an "ay-day" continuum formed by varying F1 onset frequency only. The results of a discrimination task in which the two acoustic cues were made to "cooperate" or "conflict" phonetically supported the notion of perceptual equivalence of the temporal and spectral cues along a single phonetic dimension. The results indicate that young children, like adults, perceptually integrate multiple cues to a speech contrast in a phonetically relevant manner, but that they may not give the same perceptual weights to the various cues as do adults.