Duration and Voice Quality of Early Infant Vocalizations Purpose Infant vocal durations have been studied from a variety of perspectives, including medical, social, and linguistic. The resultant developmental profile across the first 6 months of life, however, is still far from clear. The purpose of this study was to evaluate the durational properties of infant vocalizations from the ... Research Article
Research Article  |   July 13, 2018
Duration and Voice Quality of Early Infant Vocalizations
 
Author Affiliations & Notes
  • Adele Gregory
    Department of Speech Pathology, James Cook University, Townsville, Australia
  • Marija Tabain
    Department of Languages and Linguistics, La Trobe University, Melbourne, Australia
  • Michael Robb
    School of Health Sciences, University of Canterbury, Christchurch, New Zealand
  • Disclosure: The authors have declared that no competing interests existed at the time of publication.
    Disclosure: The authors have declared that no competing interests existed at the time of publication. ×
  • Correspondence to Adele Gregory: adele.gregory@jcu.edu.au
  • Editor-in-Chief: Julie Liss
    Editor-in-Chief: Julie Liss×
  • Editor: Jack Jiang
    Editor: Jack Jiang×
Article Information
Development / Speech, Voice & Prosodic Disorders / Voice Disorders / Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   July 13, 2018
Duration and Voice Quality of Early Infant Vocalizations
Journal of Speech, Language, and Hearing Research, July 2018, Vol. 61, 1591-1602. doi:10.1044/2018_JSLHR-S-17-0316
History: Received August 23, 2017 , Revised February 8, 2018 , Accepted February 28, 2018
 
Journal of Speech, Language, and Hearing Research, July 2018, Vol. 61, 1591-1602. doi:10.1044/2018_JSLHR-S-17-0316
History: Received August 23, 2017; Revised February 8, 2018; Accepted February 28, 2018

Purpose Infant vocal durations have been studied from a variety of perspectives, including medical, social, and linguistic. The resultant developmental profile across the first 6 months of life, however, is still far from clear. The purpose of this study was to evaluate the durational properties of infant vocalizations from the unique perspective of voice quality. By considering an infant's modal and nonmodal voice qualities, the developmental range of vocalizations produced by infants during the early months of life was captured.

Method Four Australian English–speaking infants were recorded for approximately 1 hr per week during the first 6 months of life. A total of 6,309 vocalizations were perceptually identified and labeled according to voice quality. The duration of each vocalization was subsequently measured.

Results A nonlinear curve was evident for the duration of all vocalizations combined. Duration increased significantly between Months 3 and 5. Modal voice was the only voice quality that displayed a linear increase in duration across the study. All other voice qualities displayed polynomial trends.

Conclusions Based on the current results, the inconsistent pattern of vocal duration development found previously can be reconciled when voice quality properties of vocalizations are taken into account. A nonlinear curve is evident when a broad corpus of infant vocalizations is used, whereas a narrow corpus containing predominantly modal vocalizations displays a linear trend. The results demonstrate the necessity of including nonmodal voice qualities in infant duration experiments so as to not overstate the linear nature of duration increases.

Acknowledgments
This research was undertaken in the first author's capacity as a PhD student of La Trobe University and was funded in part by La Trobe's FHuSS Postdoctoral Write-Up Award Scheme 2014. A preliminary version of this article appears from “Duration of Early Vocalisations,” by A. Gregory, M. Tabain, & M. Robb, 2013. Interspeech 2013. Lyon: France, pp. 1258–1262.
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