The Relationship between Vocabulary and Phonological Processing according to the Speech Sound Acquisition of 3-Year-Old Children

Purpose : This study examined the relationship between vocabulary and phonological processing skills across levels of speech sound acquisition and investigated whether speech sound acquisition influences these skills. Methods : Thirty-six typically developing 3-year-old children were divided into three groups (n = 12 each) based on their level of speech sound acquisition: Group A (complete acquisition), Group B (mispronunciations of fricatives only), and Group C (mispronunciations of fricatives and other sounds). Vocabulary skills were assessed using receptive and expressive vocabulary tests; phonological processing skills were evaluated with nonword and sentence repetition tasks. Group differences were analyzed using one-way analysis of variance (ANOVA) and Pearson’s correlation coefficient, and variable influence was evaluated using logistic regression. Results : Both vocabulary and phonological processing differed significantly across groups, with Groups A and B outperforming Group C in all tasks. Receptive and expressive vocabulary scores, and nonword and sentence repetition scores, were significantly correlated. Higher scores in both domains increased the likelihood of belonging to Groups A or B rather than Group C. Conclusions : Vocabulary and phonological processing are strongly associated in typically developing 3-year-olds and early phonological development influences these skills. These results have implications for early language assessments and intervention strategies.