Children's acquisition of consonants, semivowels, vowels, and tones in Northern Viet Nam

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The purpose of this doctoral research was to describe the speech acquisition of typically-developing Northern Vietnamese-speaking children. To achieve this overarching purpose, five aims were addressed: (1) to identify the consonants, semivowels, vowels/diphthongs, and tones of the Northern dialect compared with the Standard, Central, and Southern dialects of Vietnamese, (2) to present an overview of tone languages, (3) to develop a speech assessment to elicit speech samples from Vietnamese-speaking children, (4) to investigate children’s acquisition of Northern Vietnamese phonemes (speech accuracy, phoneme acquisition, non-adult realisations, and phonological patterns/processes), and (5) to investigate Northern Vietnamese-speaking children’s intelligibility. This doctoral research contained two parts and was presented in nine chapters, five of which were publications (one encyclopaedia entry and four journal articles). Part 1 included three comprehensive literature reviews. The first provided a review of phonological differences in the Northern Vietnamese dialect in comparison with the Standard, Central, and Southern Vietnamese dialects (Paper 1). The second provided an overview of tone languages (Paper 2). The third reviewed policy and literature about Vietnamese education and the speech-language pathology profession.Part 2 commenced with a review of definitions of typical speech acquisition, phonological theories, and research design and methods for studying speech acquisition that informed the methodology of this doctoral research. Paper 3 described the conceptualisation and operationalisation of the Vietnamese Speech Assessment (VSA, Phạm, Le, & McLeod, 2016) used to elicit speech samples during data collection. The main findings of this doctoral research were presented in Papers 4 and 5.Paper 4 described speech acquisition of 195 typically developing Northern Vietnamese children aged 2;2-5;11 years. Relational analyses were used to measure speech accuracy, phoneme acquisition, non-adult realisations, and phonological patterns/processes that resulted in four main findings. First, the accuracy scores of consonants, semivowels, vowels, and tones for Northern Vietnamese-speaking children were higher as age increased demonstrating the improvement of speech production accuracy with age. Second, by the age of 5;5-5;11, these Northern Vietnamese-speaking children had acquired all Vietnamese consonants, semivowels, vowels, and tones, with the exception of the initial-syllable consonants /ɲ, s, z, x/, the within syllable semivowel /w/, tone 3 (creaky thanh ngã), and tone 4 (dipping-rising thanh hỏi). Third, typical non-adult realisations of Northern Vietnamese consonants, semivowels, and tones were identified and variability of non-adult productions decreased in the older age groups. Fourth, common phonological patterns for younger children were fronting, stopping, deaspiration, aspiration, and semivowel deletion, and for older children were fronting and deaspiration. The children’s age and maternal education but not sex were found to influence the children’s speech accuracy.Paper 5 described parent-reported data regarding intelligibility of 181 Northern Vietnamese-speaking children aged 2;0-5;11 years and included validation of the Intelligibility in Context Scale: Vietnamese (ICS-VN, McLeod, Harrison, & McCormack, 2012). The mean ICS-VN score of Northern Vietnamese-speaking children was 4.43 (out of maximum 5.00) indicating that these children were “usually” to “always” intelligible. The ICS-VN scores were rated as significantly different between communication partners (higher ICS scores for family members and lower for strangers) and between children whose parents were and were not concerned about their speech and language skills (higher ICS scores for children with no concern). Additionally, factors significantly influencing the ICS-VN scores of Northern Vietnamese-speaking children were children’s age, parents’ occupation level, and mothers’ educational level but not children’s sex or fathers’ educational level. The findings of this doctoral research provide emerging evidence about Northern Vietnamese-speaking children’s typical speech acquisition to inform policy and practice regarding the Vietnamese Government’s Developmental Standard 15 “Trẻ biết sử dụng lời nói để giao tiếp” (The child uses speech to communicate), Item 65 “Nói rõ ràng” (To speak clearly) and Item 70 “Kể về một sự việc hoặc hiện tượng nào đó để người khác hiểu được” (To narrate an event or a fact intelligibly to others). The findings also provide emerging evidence for professionals in Viet Nam and other countries to assist with the identification of children with speech sound disorders. The doctoral research introduces and validates two assessment tools (VSA and ICS-VN) for clinical and research use with Northern Vietnamese-speaking children. The study presented in this doctoral research is aligned with other international studies about speech acquisition providing a reference for future researchers in Viet Nam.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Charles Sturt University
  • McLeod, Sharynne, Principal Supervisor
  • Harrison, Linda, Co-Supervisor
  • McCormack, Jane, Co-Supervisor
Thesis sponsors
Award date13 Dec 2018
Publication statusPublished - 2018


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