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ORIGINAL ARTICLE
Commun Sci Disord. 2021;26(1): 1-12.
Published online March 31, 2021.
doi: https://doi.org/10.12963/csd.20786
Early Emergence and Development of Protophones in the First Year of Life
Hyunjoo Yooa , D. Kimbrough Ollerb ,c , and Seunghee Had
aDepartment of Communicative Disorders, University of Alabama, Tuscaloosa, USA
bSchool of Communication Sciences and Disorders, University of Memphis, TN, USA
cKonrad Lorenz Institute for Evolution and Cognition Research, Klosterneuburg, Austria
dDivision of Speech Pathology and Audiology, Audiology and Speech Pathology Research Institute, Hallym University, Chuncheon, Korea
Corresponding Author: D. Kimbrough Oller ,Tel: +82-33-248-2215, Fax: +82-33-256-3420, Email: shha@hallym.ac.kr
Received January 5, 2021  Revised: January 30, 2021   Accepted January 30, 2021
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ABSTRACT
Objectives
Speech-like vocalizations (i.e., protophones) are precursors to speech. Infants produce various types of protophones (e.g., squeals, vocants and growls), practicing phonatory control before mastering articulation. In order to better understand infant vocal development, it is important to systematically investigate production of protophones from the beginning of life. The purposes of this study were (1) to investigate early emergence of protophones, (2) to measure volubility for both cry and protophones across the first year of life, (3) to explore effects of age and types of vocalizations, and (4) to examine protophone volubility in circumstances where the caregiver did not speak to or in the vicinity of the infant.
Methods
16 typically developing Korean-learning infants participated in all-day LENA (Language Environment Analysis) recordings in their homes as part of a longitudinal study. We categorized infant protophones as either squeals, vocants, growls, or cries based on auditory/acoustic criteria. We calculated average numbers of each type of vocalization and average vocalizations per minute. Generalized Estimating Equations (GEE), t-test, and ANOVA were conducted to address the research questions.
Results
Results showed that even in the first month of life, infants do not merely cry, but instead predominantly produce protophones. Infants also endogenously produced protophones from the beginning of life in the absence of caregiver language input.
Conclusion
This study suggests that even in the first month protophones begin to occur, and may form a foundation upon which vocal category development and vocal interaction can proceed rapidly.
Keywords: Speech-like vocalizations | LENA | Newborns | Infants | Cry
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