This study examined whether Spanish-English bilinguals are able to fully differentiate Spanish and English /t/ according to voice-onset time (VOT) if they learn English as a second language (L2) in early childhood. In experiment 1, VOT was measured in Spanish words spoken by Spanish monolinguals, in English words spoken by English monolinguals, and in Spanish and English words spoken by bilinguals who learned English either as young children or as adults. As expected, the Spanish monolinguals produced /t/ with considerably shorter VOT values than the English monolinguals. Also as expected, the late L2 learners produced English /t/ with "compromise" VOT values that were intermediate to the short-lag values observed for Spanish monolinguals and the long-lag values observed for English monolinguals. The early learners' VOT values for English /t/, on the other hand, did not differ from English monolinguals' VOT. The same pattern of results was obtained for stops in utterance-medial position and in absolute utterance-initial position. The results of experiment 1 were replicated in experiment 2, where bilingual subjects were required to produce Spanish and English utterances (sentences, phrases, words) in alteration. The results are interpreted to mean that individuals who learn an L2 in early childhood, but not those who learn an L2 later in life, are able to establish phonetic categories for sounds in the L2 that differ acoustically from corresponding sounds in the native language. It is hypothesized that the late L2 learners produced /t/ with slightly longer VOT values in English than Spanish by applying different realization rules to a single phonetic category.

/pdf/age-of-learning-affects-the-authenticity-of-voice-onset-time-yhly6blwqv.pdf

Age of learning affects the authenticity of voice‐onset time (VOT) in stop consonants produced in a second language

https://jimflege.com/files/Flege_Eefting_English_stops_JP_1987.pdf

Production and perception of English stops by native Spanish speakers

This study examined imitation of a voice onset time (VOT) continuum ranging from /da/ to /ta/ by subjects differing in age and/or linguistic experience. The subjects did not reproduce the incremental increases in VOT linearly, but instead showed abrupt shifts in VOT between two or three VOT response ‘‘modes.’’ The location of the response shifts occurred at the same location as phoneme boundaries obtained in a previous identification experiment. This supports the view that the stimuli were categorized before being imitated. Children and adults who spoke just Spanish generally produced only lead and short‐lag VOT responses. English monolinguals tended to produce stops with only short‐lag and long‐lag VOT values. The native Spanish adults and children who spoke English, on the other hand, produced stops with VOT values falling into all three modal VOT ranges. This was interpreted to mean that they had established a phonetic category {th} with which to implement the voiceless aspirated realizations of /t/ in English. Their inability to produce English /p,t,k/ with the same values as native speakers of English must therefore be attributed to the information specified in their new English phonetic categories (which might be incorrect as the result of exposure to Spanish‐accented English), to partially formed phonetic realization rules, or both.

/pdf/imitation-of-a-vot-continuum-by-native-speakers-of-english-1lksy8sv8e.pdf

Imitation of a VOT continuum by native speakers of English and Spanish: evidence for phonetic category formation.

Background
Children who are bilingual and have speech sound disorder are likely to be under-referred, possibly due to confusion about typical speech acquisition in bilingual children.

Aims
To investigate what is known about the impact of bilingualism on children's acquisition of speech in English to facilitate the identification and treatment of bilingual children with speech sound disorder.

Methods & Procedures
A systematic review of studies from the last 50 years was conducted. Studies investigating speech acquisition in bilingual infants and children (where one language was English) were identified through searching seven electronic databases, bibliographies of relevant articles and e-mailing authors. Sixty-six studies investigating bilingual speech production met inclusion criteria, with 53 describing typically developing children and 13 describing children with speech sound disorder. The 66 studies were analysed thematically and summarized in terms of methods, key findings and underlying theories.

Main Contribution
There was limited evidence to suggest that bilingual children develop speech at a slower rate than their monolingual peers; however, there was evidence for qualitative differences and increased variation in speech production. Nearly all studies provide evidence for transfer between the two phonological and language structures, although the amount of transfer varied between studies. There was evidence of positive and negative transfer of features from the dominant language (L1) to the second language (L2) as well as from L2 to L1. Positive transfer became more evident with increased age and length of exposure to a second language. More recently researchers have moved away from investigating whether there are one or two phonological systems and accept that there are two systems that interact. Interest has shifted to examining how phonological systems interact and to identifying factors that influence interactions. The review revealed a number of inconsistencies in the findings of studies due to differences in methodology, languages investigated and degree of language exposure. Overall, measurement issues were addressed well but most studies provided limited sample information about language experience, schooling and socio-economic status.

Conclusions & Implications
There are differences in speech sound acquisition between monolingual and bilingual children in terms of rate and patterns of error, with both positive and negative transfer occurring in bilingual children.

The influence of bilingualism on speech production: A systematic review

This article responds to the arguments raised against the Critical Period Hypothesis (CPH) by James Emil Flege in 'A Critical Period for Learning to Pronounce Foreign Laniuages ?'published in Applied Linguistics (8/2). An examination of the relevant literature leads to the conclusion that there is sufficient evidence to support the notion of an age-based limitation on eventual proficiency that can be attained by learners in a second language. It is argued that Flege did not represent the CPH entirely accurately, and that convincing counter-evidence to the CPH has not been presented. It is further argued that there is enough evidence to show that child second language acquirers are indeed superior in terms of ultimate ability, so that rejection of the CPH is unjustified at this time.

/pdf/age-and-accent-in-a-second-language-a-reply-3i6wt7yx83.pdf

Age and Accent in a Second Language: A Reply

Children are typically more proficient than adults in learning the phonetic detail of a second language. The purpose of this study was to investigate the acquisition of the English voicing contrast as cued by voice onset time in syllable-initial position and preconsonantal vowel duration in final position in the speech of children whose native language is Arabic. The children, 24 to 135 months in age, were recorded producing minimal pairs differing in the voicing of consonants. Voice onset time and vowel duration were measured from spectrograms. Children were highly variable in their mastery of the voicing contrast. For this sample, neither age nor experience with English could predict phonetic proficiency.

Acquisition of the English Voicing Contrast By Arab Children

Children are typically more proficient than adults in learning the phonetic detail of a second language. The purpose of this study was to investigate the acquisition of the English voicing contrast as cued by voice onset time in syllable‐initial position comparing the performance of children whose native language is Arabic with that of American English speaking children and of adult speakers of Arabic learning English as a second language. Twelve children, 24 to 135 months in age, were recorded producing 11 minimal pairs differing in the voicing of the initial stop consonant, such as pea/bee and cab/gab. Voice onset time (VOT) was measured from spectrograms for labial, apical, and velar stops. Children were highly variable in their mastery of the voicing contrast; neither a child's age nor his experience with English could predict his phonetic proficiency.

Marcy Steinberg

Papers

Acquisition of the English Voicing Contrast By Arab Children

Acquisition of the English voicing contrast by Arabic children