Acoustic Properties of Turkish Sibilants in Cleft Palate Speech

Objective: Cleft lip and palate is one of the most common birth defects. It may result in anatomical differences, feeding, dental, hearing, and speech problems. Many speech problems occur due to insufficient velopharyngeal closure, and this causes inappropriate air leakage to the nasal cavity resulting in hypernasality. In such speech, the obstruent sounds are weakened or distorted. The aim of this study is to analyze the acoustic properties of Turkish fricatives of children with cleft lip and palate having hypernasality. Methods: For this purpose, duration, voicing duration, center of gravity (M1), skewness (L3), and kurtosis (L4) values of sibilants (/s, z, ʃ, ʒ/) were measured. Each sibilant was located word-initial position within a sentence. Four children with cleft palate with hypernasality and 4 children without cleft palate participated in the study. All the participants were Turkish native speakers, and their age range was 10-12. The data was analyzed with R and linear mixed model. Results: It has been seen that the duration of target sounds is longer for children with cleft palate having hypernasality. Moreover, M1 is found lower for these participants than those without hypernasality. Although L3 does not show any discrepancy for both groups, L4 is lower for the children with cleft palate having hypernasality. Conclusion: It has been found that hypernasality affects the duration, M1 and L4 of target sibilant sounds. All results have shown that children with hypernasality need more time and prefer back articulation to create the intra-oral pressure; however, they canno create enough turbulence required for fricatives. Cite this article as: Balo E. Acoustic properties of Turkish sibilants in cleft palate speech. Arch Health Sci Res. 2024;11(2):70-76.