Publication Date



Open access

Embargo Period


Degree Type


Degree Name

Doctor of Philosophy (PHD)


Music Education and Music Therapy (Music)

Date of Defense


First Committee Member

Stephen F. Zdzinski

Second Committee Member

Don D. Coffman

Third Committee Member

Corin Overland

Fourth Committee Member

Rachel Lebon

Fifth Committee Member

Julia Gerhard


The purpose of this study was to examine the relationship of Motivation, Affective State and Physiology on the vocal outcomes of Range, Registration Fluency, and Vocal Quality. Participants were members of community boys’ choirs from four states (N = 196). Surveys on motivation and mood provided the psychological data. Height, weight, and lung capacity measures provided physiological data. Sound data consisted of glides, speech and messa di voces. Data analysis included Pearson correlation analysis, exploratory factor analysis and two-step maximum likelihood structural equation modeling. Results indicated a strong effect of Physical Maturity on Registration Fluency. Correlations among observed variables height, age, and speaking pitch with ranges in upper and lower registers, intensity ranges and breathiness confirmed previous research on adolescent male signing. Motivation had a moderate effect on Range (𝛽 = .13). Speaking Vocal Quality strongly predicted Range (𝛽 = -.22). Physical Maturity had strong effect on Registration Fluency (𝛽 = .27). Physical Maturity outcomes predicted Range (𝛽 = -.08) indicated by multiple registers, which supported elements of both the Eclectic Theory (Cooksey, 2000a) and Expanding Voice Theory of voice change (Leck, 2009; Phillips, Williams, & Edwin, 2012; Williams, 2013).


adolescent male; boy choir; registration; vocal; psychological; motivation; model; singing