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The purpose of this study is to present a comprehensive model for speech sound development by comparing the results of performance with segmental and wholeword 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 wholeword 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).