Electronic Theses and Dissertations




Hyunjoo Yoo



Document Type


Degree Name

Doctor of Philosophy


Communication Sciences & Disorders

Committee Chair

D. Kimbrough Oller

Committee Member

Eugene Buder

Committee Member

Dale Bowman

Committee Member

Gavin Bidelman

Committee Member

Miriam van Mersbergen


Caregiver-infant interaction is critical for cognitive, social, emotional, and language development. This dissertation investigated adult responses to infant speech-like (i.e., protophones) and distress vocalizations in three individual projects. Study1 investigated different timing of caregiver responses to protophones and cries. In order for caregivers to respond differently to protophones and cries, they need to be able to differentiate these sounds. Study 2 and Study 3 projects addressed this issue. Infant recordings from a longitudinal study were used for the dissertation. For Study 1 and 3, all-day LENA home recordings were used, and for Study 2, both LENA and laboratory recordings were used. Adult listeners for Study 2 and 3 were students and/or staff in the School of Communication Sciences and Disorders. Pupillometry and reaction time were used in Study 2 to measure listeners’ cognitive load when judging infant vocalizations. Study 1 found that caregivers tended to take turns with protophones, suggesting they viewed protophones as conversational material, while they tended to overlap with cries from the first months of life. This result is important because it suggests parents know that protophones are precursors to speech even in the first months of life, whereas cries express distress, and caregivers intuitively treat them as not being conversational material. Study 2 found that nonparent adult listeners were reliably able to identify high-distress wail cry and mid-distress whine. Listeners judged cry faster in a speech-babble noise condition than in a no-noise or a music-masking condition, a pattern consistent with the fast-guessing principle. Greater pupil dilation was found when listeners identified whine than when they identified cry in the noise condition, suggesting there was greater cognitive load in the noise condition. Study 3 documented that 39 listeners agreed with each other highly in rating levels of distress in infant vocalizations ranging from cries to protophones. The study also showed that moments of the long-term average spectrum in vibratory regimes within utterance, utterance duration, number of acoustic regimes, and maximum fo were strong predictors of the ratings of levels of distress. In addition, regardless of experience in infant vocalization coding, listeners were not significantly different in perceiving the level of distress.


Data is provided by the student.

Library Comment

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