PhD, University of Cincinnati, 2011, Allied Health Sciences: Communication Sciences and Disorders

Cool-down exercises are routinely prescribed for singers, yet few data exist about the efficacy of active recovery or cooling down of the vocal mechanism. The purpose of the present study was to compare three aspects of vocal function after using different recovery methods following rigorous voice use. Vocal function was assessed using (1) phonation threshold pressure (PTP); (2) acoustic measures (accuracy of tone production, duration of notes and duration of intervals between notes); and (3) measures of subjective perception: perceived phonatory effort (PPE) and Singing Voice Handicap Index (SVHI). Data were collected after 10-minutes of cool-down exercises, complete voice rest, and conversation immediately following a 50-minute voice lesson. Data were collected again 12-24 hours later. Participants included actively performing elite singers (7 women, 2 men) enrolled in the graduate program (M.M., D.M.A.) at the University of Cincinnati's College-Conservatory of Music. While it was expected that PTP estimates after cool downs would be significantly lower than baselines and the other conditions, it turns out that PTP estimates after cool downs were significantly higher at the 80% level of the pitch range. Statistically significant correlations between PTP estimates and PPE scores were found when comparing levels of the participants' pitch ranges (10%, 20%, 80%). Mean PPE scores were highest at the 80% level of the pitch range. The acoustic measures yielded variable results. Cool-down exercises did not result in significantly more accurate tone production and shorter staccato note duration and duration of intervals between staccato notes as compared to baselines and recovery conditions. Instead, participants demonstrated greater accuracy of tone production during baselines and lesser accuracy after voice rest. Staccato notes were significantly shorter in duration after the conversation condition as compared to voice rest. Duration between staccato notes was signific (open full item for complete abstract)

Committee: Lisa Kelchner PhD (Committee Chair); Suzanne Boyce PhD (Committee Member); Wendy Leborgne PhD (Committee Member); Mary Stucky MM (Committee Member); Bradley Wilson PhD (Committee Member) Subjects: Speech Therapy

Master of Science (MS), Bowling Green State University, 2009, Physics

Titze (1988) used the surface wave model to derive an analytical expression for threshold pressure in terms of the glottal geometry and biomechanical parameters of the larynx. This formula was tested in a series of experiments in 1995 and 1997. Since the membrane of the physical model used in the experiments becomes rounded when a fluid flows beneath it, the effects of glottal curvature were investigated. Because physical model used for the experiments could be adjusted to give a divergent prephonatory glottal geometry, an angle θ was also introduced in addition to the curvature correction. Including the curvature coefficient b and the prephonatory glottal angle θ do not seem likely candidates for discrepancies observed in the experiments because such effects are hard to distinguish from changes in the effective values of the glottal halfwidth and the damping coefficient. Nardone's mathematical model was built from the classic, lumped element, two-mass model of Ishizaka and Flanagan. The mathematical model is based on ten, second-order, nonlinear, coupled, ordinary differential equations that are solved simultaneously using the software Mathematica. Nardone's model was employed to study the role of vocal tract parameters and viscous damping constants in determining the threshold pressure. Calculated results were compared with Chan and Titze's (2006) experimental data. The results indicate that the threshold pressure is consistently lowered when the vocal tract is included, which follows the same trend as the experimental results of Chan and Titze (2006). Increasing the vocal tract area in the mathematical model achieved a larger difference between the calculated results with vocal tract and with a larger vocal tract area. We have also shown that an increased viscous damping constant leads to a bigger threshold pressure differences. Comparison of the calculated results with Chan and Titze's (2006) experiments were not able to generate a consistent fit over the entire (open full item for complete abstract)

Committee: Lewis Fulcher PhD (Advisor); Ronald Scherer PhD (Committee Member); Haowen Xi PhD (Committee Member) Subjects: Biophysics