Vocal motor control in school-age children with and without vocal fold nodules
Heller Murray, Elizabeth
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The purpose of this dissertation was to examine voice and vocal motor control in school-age children (5 – 12 years of age) with vocal fold nodules (CwVN) and children with typical voices (CwTV). This work is divided into three chapters, the first two examining CwTV and CwVN and the third providing a comprehensive examination of vocal motor control in adults and children without voice disorder. Study one analyzed relative fundamental frequency (RFF), an acoustic measure of fo change during vowels before and after a voiceless consonant. Average RFF values for offset cycle 10 and onset cycle 1 did not differ between CwVN and CwTV; however, variability of offset cycle 10 was decreased in CwVN. Across both groups, male children had lower offset cycle 10 RFF values as compared to female children. Additionally, onset cycle 1 values were decreased in younger children as compared to older children. Study two examined auditory discrimination to changes in vocal fo in CwVN and CwTV. There were no differences in pitch discrimination abilities between CwVN and CwTV. Younger CwTV had significantly poorer discrimination than older CwTV and adults. However, some CwTV across all ages examined were able to achieve adult-like discrimination abilities, suggesting that these abilities are mitigated by more than solely age in children. Study three evaluated the relationships among vocal pitch discrimination, feedback control, and sensorimotor adaptation in vocally healthy children and adults. Prior to analysis, children were subdivided into two groups based on their auditory discrimination abilities, defined as either being adult-like or immature. Children with immature auditory pitch discrimination had significantly larger vocal responses to unexpected pitch-shifts and significantly smaller responses to sustained pitch-shifts over time.