Developmental Analysis in Korean Children's Speech Production Using Percentage of Consonants Correct and Whole-Word Measurements

Objectives: The purpose of this study is to present a comprehensive model for speech sound development by comparing the results of performance with segmental and whole-word measurements on the data collected for a large number of children by age. Methods: We conducted a word-level test of the Urimal Test of Articulation And Phonolog-2 (UTAP2) for typically developing children from 2 to 7 years of age in Seoul, Gyeonggi-do, Chungcheong-do, Kyongsang-do, Jeolla-do and Jeju-do in Korea. We assessed children's speech production using various measurements of percentage of consonants correct (PCC), percentage of consonants correct-revised (PCC-R), proportion of whole-word proximity (PWP), phonological mean length of utterance (PMLU), and proportion of whole-word correctness (PWC). After dividing the ages into nine groups, we compared the differences in speech production according to gender and age group at each speech index. Results: There was no statistically significant difference in all indicators between sexes, but age differences were significant. PCC and PCC-R significantly increased the index values until the age of 4 years and 11 months old, and the whole-word measurements increased significantly until the age of 5 years and 5 months old. Conclusion: The results of this study are summarized and the following model is proposed for speech sound development: 'production period of speech sound' (age from 1 to early 2), expansion period of the speech sound inventory' (age from late 2 to early 3), 'elaboration period of speech' (age from late 3 to late 4), and 'stabilization period of speech acquisition' (age from early 5 to age 6).