Aerodynamic, Acoustic, and Vibratory Consequences of Subglottic Stenosis in a Model of the Respiratory Airway Containing Self-Oscillating Vocal Fold Replicas

Subglottic stenosis (SGS) is characterized by a narrowing of the airway below the vocal folds. The extra growth—frequently made of scar tissue—is most commonly caused by prolonged intubation or trauma to the area, although it can develop as a result of disease or be idiopathic. While SGS clearly inhibits respiration, the aerodynamic and acoustic consequences of SGS on voicing remain relatively understudied. It is hypothesized that the jet caused by SGS has the potential to impinge on the vocal folds, causing additional sound production and an altered loading on the vocal folds. For this study, an adjustable, actuated device simulating subglottic stenosis was developed. Synthetic models of the vocal folds in conjunction with upper and lower airway replicas, the latter including regions with geometric changes representative of SGS, and the former including different vowel-vocal tract configurations, were used to explore the influence of SGS on vibratory and acoustic output during voicing. Measurement methods and results are described, including data characterizing the relationships between SGS severity and parameters such as onset pressure, vocal fold model vibratory response, and radiated acoustic spectra.