Effects of surgery on the relationship between subglottic pressure and fundamental frequency in vocal fold dynamics in patients with benign laryngeal diseases.

PURPOSE: Subglottic pressure (Ps) and fundamental frequency (F0) play important roles in governing vocal fold (VF) dynamics. Theoretical description, model simulation, excised larynx and animal models have been used in previous studies, yet clinically applicable measurements are still lacking. This study aimed to evaluate the effects of surgery for benign laryngeal lesions by investigating the relationship between F0 and Ps. METHODS: Patients with benign laryngeal lesions who underwent phonosurgery were prospectively recruited. Participants were instructed to sustain voicing the vowel /o/ at three incremental frequencies four semitones apart in the modal register (F01, F02, F03). F0 was estimated by VF vibration on the accelerometer. Ps change was achieved and measured using the airflow interruption method. RESULTS: Thirteen patients with a mean age (SD) of 43.5 (12.4) years were included. The change in F0 per unit change of Ps, which is the slope (Hz/kPa) of the regression line of the frequency-pressure data pairs, decreased as the tension of the VF increased. The slopes significantly increased after the operation for F01 and F02 (36.43 ± 14.68 preoperatively, 53.91 ± 30.71 postoperatively, p = 0.011 and 26.02 ± 10.71; 34.85 ± 17.92, p = 0.046, respectively). In addition, there was a significant decrease in phonation threshold pressure and improvements in the grade, roughness, breathiness, asthenia, strain scale, and the voice handicap inventory-10. CONCLUSIONS: The relationship between F0 and Ps may serve as an objective assessment of the outcomes in the treatment of benign laryngeal diseases with clinical relevance.

Estimating vocal fold stiffness: Using the relationship between subglottic pressure and fundamental frequency of phonation as an analog.

OBJECTIVE: The stiffness of the vocal folds is an important factor in voice production, yet clinically applicable measurements are still lacking. It has been demonstrated in an in vivo canine model that fundamental frequency (F0 ) increased linearly as subglottic pressure (Ps ) increased, but with a lesser slope for higher levels of vocal fold tension. In this study, the relationship between F0 and Ps was investigated using the airflow interruption method in awake patients non-invasively. DESIGN: Healthy volunteers enrolled for evaluation. SETTING: Single-centre. PARTICIPANTS: Thirty-three healthy volunteers aged 20 and older were recruited, with one excluded for a recent asthma attack. MAIN OUTCOME MEASURES: The relationships between F0 and Ps , described as the slope (Hz/kPa), were investigated when the participants sustained voicing the vowel/o/at 3 incremental frequencies 4 semitones apart in the modal register (F1, F2 and F3). RESULTS: Thirty-two healthy volunteers (20 females, 12 males) aged 20-47 years were enrolled for final analyses. There was a statistically significant difference in the slopes of the linear regression lines of F0 -Ps , depending on the frequency with which the vowel/o/ was produced (P < .001). The slope differed significantly between F2 and F1 (P < .001; P = .015), F3 and F1 (P < .001; P = .002) and F3 and F2 (P < .001; P = .005) for both women and men, respectively. CONCLUSIONS: It was demonstrated that the higher the vocal fold tension, the smaller the slope between F0 and Ps . Using the relationship between F0 and Ps as an analog of vocal fold stiffness is potentially practical for clinical application.