Nasalance scores for normal Korean-speaking adults and children: Effects of age, vowel context, and stimulus length

ObjectivesThe purpose of this study was to collect nasalance scores for normal Korean-speaking children and adults and to determine whether age, vowel contexts, and stimulus length influence nasalance scores.MethodsFifty-seven children aged 4–6 years and 17 adults participated in the study. Mean nasalance scores were obtained for eight sentences devoid of nasal consonants divided into the vowel/a/and/i/contexts; the sentences consisted of 4, 8, 16, and 31 syllables. All subjects were asked to repeat the speech stimuli twice after the examiner. The headset of the nasometer was replaced between the first and second recordings. An average value of the nasalance scores from the two recordings for each stimulus was calculated and used in the statistical analysis as a representative measure for each subject.ResultsMean and standard deviations of nasalance scores were obtained for each speech stimulus and each age group. The statistical analysis indicated significant effects of age and vowel context and a significant interaction between age and the vowel context on nasalance scores. However, the effect of stimulus length on nasalance scores was not significant. All speakers had higher nasalance scores for the vowel/i/contexts than for the vowel/a/contexts. Adults had higher nasalance scores compared to children in both vowel contexts.ConclusionsThese normal nasalance values from Korean-speaking children aged 4–6 years will provide important reference information for resonance assessment of children with cleft palate who have been considered for secondary palatal surgery. The results of the study suggest that subjects’ age and the vowel content of speech stimuli should be carefully considered when interpreting the nasalance scores.