Characteristics of Alveolo-palatal Affricates Produced by Mandarin-speaking Children with Repaired Cleft Palate.

Abstract

Objectives: In this study, examined the acoustic properties of affricates /t/ and /th/ in Mandarin Chinese, and analyzed the differences of the acoustic characteristics of these affricates produced by children with repaired cleft palate and normally developing children. We also explored the relationship between the affricates and high-front vowel /i/. Methods: We analyzed 16 monosyllabic words with alveolo-palatal affricates as the initial consonants produced by children with repaired cleft palate (N=13, Mean=5.9 years) and normally developing children (N=6, Mean age=5.3 years). We used several acoustic parameters to investigate the characteristics of these affricates, such as the center of gravity, VOT and the formants of vowels. Results: Compared with normally developing children, children with cleft palate exhibited a lower center of gravity for the 2 affricates /t/ and /th/. Data from the control group showed that the affricate /th/ had a significantly greater center of gravity than that of /t/. The accuracy of /t , th/ produced by speakers of cleft palate was significantly correlated with that of /i/ (r=0.63). High-front vowel /i/ is a significant index in diagnosing speech intelligibility which is more valuable than /a/ and /u/. There was a significant difference in F2 of vowel /i/ between children with cleft palate without speech therapy (CS1) and after speech therapy (CS2). After speech intervention, the accuracy of affricates produced by children with cleft palate was improved, the acoustic properties "stop + noise segments" appeared. Conclusion: Children with cleft palate can be distinguished better from children with normal development by 2 significant acoustic characteristics: center of gravity and VOT. As alveolo-palatal affricates /t , th/ and high-front vowel /i/ have a similar place of articulation, front-tongue-blade, their production accuracy can be improved mutually. The analysis showed that the articulation of Chinese /i/ has a higher frontal lingual position and less variability, which is more conducive to articulation training and improves the effect of cleft palate training. These findings provide a potential relationship on affricates /t, th/ and vowel /i/. Children with cleft palate have difficulty pronouncing the /t, t h/ and /i/. It is better to start with a vowel /i/, resulting in improvement in overall speech intelligibility.