Comparing the Temporal Aspects of Velopharyngeal Closure in Children with and without Cleft Palate.

Introduction: Children with cleft palate exhibit differences in the 4 temporal components of nasalization (nasal onset and offset intervals, nasal consonant duration, and total speech duration), with various patterns having been noted based on different languages. Thus, the current study aimed to examine the temporal aspects of velopharyngeal closure in children with and without cleft palate; this is the first study to do so in the Turkish language.

Methods: This study evaluated and compared the 4 temporal characteristics of velopharyngeal closure in children (aged 6-10 years) with (n = 28) and without (n = 28) cleft palate using nonword consonant and vowel speech samples, including the bilabial nasal-to-stop combination /mp/ and the velar nasal-to-stop combination /ηk/. Acoustic data were recorded using a nasometer, after which acoustic waveforms were examined to determine the 4 temporal components of nasalization. Flexible nasoendoscopy was then used to evaluate velopharyngeal closure patterns.

Results: With regard to the 4 closure patterns, significant differences in the nasal offset interval (F4-25 = 10.213, p = 0.04; p < 0.05) and the nasal consonant duration ratio (F4-25 = 12.987, p = 0.02; p < 0.05) were observed for only /ampa/. The coronal closure pattern showed the longest closure duration (0.74 s). Children with cleft palate showed prolonged temporal parameters in all 4 characteristics, reflecting oral-nasal resonance imbalances. In particular, the low vowel sound /a/ was significantly more prolonged than the high vowel sounds /i/ and /u/.

Conclusions: The examined temporal parameters offer more accurate characterizations of velopharygeal closure, thereby allowing more accurate clinical assessments and more appropriate treatment procedures. Children with cleft palate showed longer nasalization durations compared to those without the same. Thus, the degree of hypernasality in children with cleft palate may affect the temporal aspects of nasalization.