An electropalatographic investigation of lingual consonants produced by a typically developing 9-year-old boy
(2017) An electropalatographic investigation of lingual consonants produced by a typically developing 9-year-old boy, no. 115.
Background: Electropalatography has been used for many years in the treatment of children with intractable speech disorders. However, to this day, children's tongue-palate contact patterns are compared to adult patterns as there are no published norms for children. Previous studies have found that children's lingual motor control continues to develop into adulthood. This can cause a problem when comparing to typical adult data, as development may cause a child's tongue-palate contact patterns to be different than adults. The focus of the current pilot study was to find useful information to help in the development of methodologies for future research to eventually develop EPG norms for children. Aims: 1. To identify and chart lingual palatal contact patterns for a range of lingual consonants for a typical 9-year-old boy. 2. To identify any differences in lingual palatal contact patterns between a typically developing 9-year-old boy and adult typical data provided by McLeod and Singh (2009). Methodology: This pilot study analysed pre-existing data to identify tongue-palate contact patterns for a typically developing 9-year-old boy. The lingual consonants of focus were /t/, /d/, /n/, /k/, /g/, /ŋ/, /s/, /z/, /ʃ/, /l/, /ɹ/, and /j/. The phonemes were present in single-word and sentence-level wordlists. These wordlists presented the target phonemes in word-initial and word- final positon and in various vowel contexts. The maximum point of contact was identified for each target sound which enabled the variability index to be calculated and cumulative displays to be created. The tongue-palate contact patterns and the variability index were charted to identify intra-speaker variability, and the cumulative displays were compared to typical adult patterns to identify if any inter-speaker variability could be found. Results: The participants' tongue-palate contact patterns on the most part showed consistent shapes throughout, however, they did remain variable as a decrease in variability over a three-month period was not observed. Vowel context appeared to have an influence on variability for alveolar and velar stops. When comparing to adult patterns, the child appeared to have differences in tongue-palate contact patterns for all the lingual consonants apart from /k/. Conclusions: The findings suggested that the child was continuing to go through a period of refinement of their lingual motor control, as variability was seen throughout the data and differences in contact patterns were observed when compared to adults. However, meaningful conclusions could not be made as the data was limiting due to varying repetitions and vowel/word contexts. Despite this, the current pilot study did find information that is essential to the development of methodologies for future EPG research focusing on typical children. A study was proposed taking the limitations from this pilot study into consideration, so that child EPG norms could be established in the future.