Date of Award

Spring 2019

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

School

Psychology

Committee Chair

Dr. Alen Hajnal

Committee Chair School

Psychology

Committee Member 2

Dr. Valeria Vergara

Committee Member 3

Dr. Richard Mohn

Committee Member 3 School

Education

Committee Member 4

Dr. Donald Sacco

Committee Member 4 School

Psychology

Abstract

There is a shortage of literature regarding beluga (Delphinapterus leucas) vocal ontogeny, as presently, there has only been one published study on the vocal development of beluga calves, despite the value of ontogenetic studies for our understanding of sound-centered species. Here I offer the second longitudinal study of beluga vocal development. Using a calibrated digital hydrophone with a sampling rate of 256 kHz, I studied the vocal progression of a male beluga calf in early life. From his first day, the calf produced broadband pulse trains with upper frequency limits extending past the study’s Nyquist frequency (128 kHz); higher than what was initially reported in studies limited by lower sampling rates. Pulse signals were the most common sound type in the calf’s vocal repertoire during his first year. Mixed calls were produced in month one but were rare overall and not regularly produced until the calf’s fifth month of life. Tonal production was also infrequent and not apparent until month four. Over the calf’s first month of life, pulse repetition rate, source level, and third quartile frequencies of the calf’s pulse trains increased significantly. First and third quartile, center, and peak frequencies increased significantly over the first year, as did pulse repetition rate and call duration. In his second year of life, the calf developed a contact call that was most similar to his mother’s, analogous to the contact call acquisition of other beluga calves. Parallel findings from this and previous studies imply species-specific trends in vocal development.

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