Electronic Theses and Dissertations

Identifier

1076

Maki Doiuchi

Date

2014

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Comm Sciences and Disorders

Concentration

Speech Lang Sci & Disorders

Committee Chair

Eugene H Buder

Committee Member

Michael P Cannito

Committee Member

Joel C Kahane

Committee Member

D Kimbrough Oller

Abstract

The purpose of this dissertation was to explore vibratory regime of infant phonation. The first study examined 1) differences in overall levels of acoustic and respiratory variables between different regimes and 2) differences in relationships between the acoustic and respiratory variables among regimes. The second study examined 3) the acoustic and respiratory ranges of modal phonation with respect to other regimes and 4) the range of modal phonation among infants of different ages. Two datasets were used in the study. Dataset I was acquired from eight infants of ages 8-18 months, and Dataset II from one infant of ages 4-6 months. Their vocalizations and respiratory movements were recorded during adult-interaction. Phonated segments were identified through waveform, spectrogram, and auditory inspection, and categorized into six mutually exclusive regimes (modal, pulse, loft, subharmonics, biphonation, and chaos). For each regime segment, the following measurements were made: fundamental frequency (F0), sound pressure level (SPL), expiratory slope, and relative lung volume at regime initiation. A series of linear mixed-effects model analysis and analysis of variance revealed differences in mean F0 between regimes, mean SPL, and mean. Correlations between the acoustic and respiratory variables differed among regimes, indicating their relationships were regime-dependent. The most revealing findings were that regime categories readily distributed into different regions of the intensity-frequency space, and that F0 ranges of modal regime tended to decrease with increasing age. In addition to modal, pulse, and loft distributing around the mid, low, and high intensity-frequency regions, respectively, biphonation and subharmonics were found between modal and loft ranges. The upper end of F0 range for pulse was much higher in infants compared to adults, however, biphonation and subharmonics rarely occurred between pulse and modal ranges. A range of modal F0 was about 500 Hz for the young infant in the vocal expansion stage, and about 200 Hz for older infants in the (post-)canonical stage. Although the results are tentative, this finding suggests that F0 variability decreases with age and phonation becomes more restricted to a lower end of an F0 range.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.

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