Characteristics of Nasal Coarticulation by Nasality Visualization System in Children with Speech Sound Disorders

Objectives: In this study, we analyzed the nasal coarticulation characteristics of children with and without speech sound disorders by comparing nasalance scores according to speech contexts. Methods: The subjects of this study were 30 children, 15 children with speech sound disorder (SSD) and 15 typically developing (TD) children, aged 4 to 6 years old. Subjects were asked to speak stimuli in different speech contexts-low vs. high vowels, nasal consonant+vowel (NV) vs. vowel+nasal consonant (VN) syllables, words vs. nonwords - and nasalance scores were measured using the Nasality Visualization System (NVS) on their speech samples. Results: First, both groups showed significantly higher naslance scores for high vowels compared to low vowels, with a significant between-group difference in high vowel. Second, both groups showed significantly higher nasalance scores for VN syllables than for NV syllables, with no between-group difference. Third, both groups showed significantly lower nasalance scores in nonwords compared to words. While there was no group difference in the words, the nasalance scores of the SSD group was lower in the nonwords, which was significantly different from that of the TD groups. Conclusion: These results suggest that the SSD group exhibits somewhat different nasal characteristics than the TD group, and furthermore, that SSD children articulate phoneme sequences more segmentally in unlearned nonword contexts.