Abstract:
Aims: Aims of this doctoral thesis were to: 1) develop linguistic and cultural guidelines when working with Mandarin-English bilingual children and families in a clinical setting, 2) investigate typical phonological development (phonetic inventories, phonological accuracy, speech error patterns) of Mandarin-English bilinguals aged 5;0-7;11 years in New Zealand (NZ) and 3) explore potential factors (age, gender, socio-economic status (SES), language background and exposure, time in NZ) impacting on development. Methods: This is a cross sectional study on 326 typically developing Mandarin-English bilingual children aged 5;0 to 7;11 years. Children’s phonological skills were assessed using the Diagnostic Evaluation of Articulation and Phonology assessment (Dodd, Zhu, Crosbie, Holm, & Ozanne, 2002) and an adapted Mandarin word test (Zhu & Dodd, 2000a). Consonant and vowel inventories were established for each child in both languages. English and Mandarin phonological accuracy was measured through: percent consonants correct (PCC), percent vowels correct (PVC) and percent phonemes correct (PPC). Additionally, Mandarin tonal percentage was examined. Speech error patterns were identified and further categorised into segmental and syllable error patterns. Multiple linear regression was then performed to examine possible links between demographic factors and phonological accuracy measures. Results: Findings show that while phonetic inventories were similar to that found previously for monolinguals in both languages, there are differences in accuracy measures and speech error patterns between the bilingual children and their monolingual peers in both Mandarin and English. Bilinguals had lower accuracy across all measures for English and Mandarin with the exception of Mandarin PVC and tone accuracy, which showed a ceiling effect. Key factors that had significant impacts on accuracy measures included age, time in NZ, language background and exposure. Bilinguals had error patterns that would be classified as delayed (e.g. gliding, cluster reduction) and atypical (e.g. backing, epenthesis) in monolingual populations. Conclusions: Phonological development of Mandarin-English bilinguals is quantitatively and qualitatively different in comparison to monolingual peers. Phonological development is still a dynamic process for these bilinguals, even at 7;11 years. The descriptive results reported here for Mandarin-English bilinguals aged 5;0-7;11 years in NZ will be valuable when distinguishing language difference from disorder in this population. Findings will support clinical decision making and enable better differential diagnosis for Mandarin-English speaking children with suspected speech sound difficulties and will facilitate the development of guidelines for therapeutic intervention