This thesis examined the effects of combination inhaled corticosteroids (ICs) on the stability of six aerodynamic measures of phonation utilizing a traditional benchtop model with leporine larynges. The motivation for this study was based on the increase of voice disorders associated with IC use in recent years. The aerodynamic measures examined were phonation threshold pressure (PTP), phonation threshold flow (PTF), onset resistance, sustained pressure, sustained flow, and sustained resistance. Leporine larynges were selected as the model for this study due to histological similarities between leporine and human vocal folds that make them ideal for translational research. Rabbits were either exposed to saline solution or ICs for 8 weeks before being sacrificed. After being sacrificed, larynges were excised and dissected. After dissection, the larynges were mounted on a benchtop, the aerodynamic data were gathered, and stability over multiple phonation trials was calculated. The results indicate that the variation between individual rabbits across the measures did not differ significantly. However, after controlling for trial, the average variation of the groups across all trials did differ significantly. PTP and sustained pressure were more variable for the inhaler group, while PTF, sustained flow, onset resistance, and sustained resistance were more variable for the control group. These results suggest that some level of variability in aerodynamic measures both within and between subjects is to be expected when using the leporine benchtop model. Furthermore, while IC exposure does not seem to impact within-subject variability, it does influence between-subjects variability.

Combination corticosteroid inhalers are the primary treatment option for long-term pulmonary disorders including asthma, persistent bronchitis, and chronic obstructive pulmonary disease. Common side effects of these medications are xerostomia in the mouth and throat, hoarseness, and soreness in the oropharynx. Research indicates that a large percentage of the inhaler particles are deposited onto laryngeal tissue, leaving an alteration of laryngeal mucosal properties. As the first stage in a long-term project, this thesis addresses the need for baseline phonatory data that will lay groundwork for quantifying inhaler-induced phonatory changes. Excised larynx research is a powerful tool for assessing aerodynamic alterations that accompany laryngeal pathology. Porcine (pig) larynges are a traditional species employed in voice disorder research, though leporine (rabbit) larynges are an emerging species that lends itself to histologic vocal fold studies as they have the most similar vocal fold cover structure to humans compared to any other animal to date. The purpose of this study was to examine the measurement stability of six aerodynamic parameters in a traditional excised larynx benchtop model. Specifically, the current author assessed measurement stability of leporine larynges compared to porcine larynges with the following aerodynamic metrics: phonation onset pressure (PTP; cmH2O), phonation onset flow (PTF; L/m), sustained pressure (cmH2O), sustained flow (L/m), onset laryngeal resistance (cmH2O/L/m), and sustained laryngeal resistance (cmH2O/L/m). A total of 30 larynges—15 leporine and 15 porcine—were mounted on a benchtop setup; phonation was sampled over 15 trials for each larynx. Measurement stability for the above six tokens was examined using coefficient of variation (%) analyses. Leporine larynges demonstrated significantly less variation across all six aerodynamic parameters when compared to porcine larynges. The leporine PTP values were most stable as compared to leporine and porcine pressure and airflow values. Leporine airflow values were also more stable than porcine PTP and PTF values. These results indicate that leporine larynges might be a preferred excised larynx specimen for certain benchtop phonation studies. These findings are important for establishing expected measurement variability in porcine and leporine larynges, particularly when translating benchtop research to laryngeal pathology.