There are many conditions and diseases that affect voice production. One of these, subglottic stenosis (SGS), is characterized by a narrowing of the trachea near the cricotracheal junction. SGS causes dyspnea (labored breathing) and frequently surgery is necessary to eliminate the airway obstruction. SGS is also believed to adversely affect voice quality. While significant research has been conducted to study the effect of SGS on breathing, relatively few studies concerning its effect on voice production have been performed. The purpose of this research was to provide quantitative results concerning the predicted effects of SGS on vocal fold (VF) vibration and resulting sound production, and to provide tools for more extensive research involving synthetic VF models in the future. This was achieved through an experimental procedure in which a device simulating SGS was coupled with synthetic VF models and acoustic, aerodynamic, and vibratory measurements were acquired. Additionally, a device was developed and tested to study the effects of VF posturing using synthetic VF models. The design of the device is anticipated to serve as a useful tool in future experiments.The device simulating SGS was capable of creating an artificial stenosis of adjustable severity. The device was designed so that synthetic VF models inserted into rigid plates could be placed on top of the device, downstream of the stenosis. An experiment was conducted with the SGS device in conjunction with synthetic four-layer VF models in which flow and pressure were measured, radiated sound data were recorded, and visual data from a high-speed camera were captured as the percent obstruction was changed. The effects of subglottic stenosis were quantified using metrics such as onset pressure, glottal area, smoothed cepstral peak prominence (CPPS), harmonic-to-noise ratio (HNR), acoustic spectra, air flow, and pressure below and above the stenosis. The results show that the glottal area was not noticeably affected by the stenosis until 80% or 90% obstruction, and flow resistance through the stenosis was not significantly affected until 85% obstruction. However, changes in acoustics occurred as low as 65% or 70% obstruction.An MRI-compatible posturing device was developed which was capable of causing abduction/adduction and elongation in synthetic VF models. The device was used to adduct synthetic VF models from an abducted position into a pre-determined final phonatory posture as high-speed video and pressure data were collected. The device adducted to final phonatory posture in 500 ms, and phonation was initiated 680 ms later. In addition, the elongation of the synthetic models was varied as high-speed data were collected. The frequency of vibration of the four-layer models was found to not vary significantly when the models were elongated.
College and Department
Ira A. Fulton College of Engineering and Technology; Mechanical Engineering
BYU ScholarsArchive Citation
Hilton, Benjamin Allen, "The Effect of Subglottic Stenosis on the Aerodynamic, Acoustical, and Vibratory Output of Synthetic Vocal Fold Models" (2019). Theses and Dissertations. 7595.
synthetic vocal fold, subglottic stenosis, stenosis, vocal fold posturing, MRI