Short-Term Evaluation of Laryngeal Double Valve Function in Phonation in Vocally Healthy Adults Using Electroglottographic and Acoustic Analyses.

OBJECTIVES

The laryngeal double valve function (LDVF) principle posits that various laryngeal sphincter systems (eg, vocal folds and ventricular folds) are differently engaged in activities requiring breath control. The vocal folds may act as an inspiratory valve, while the ventricular folds with the aryepiglottic structures function as an expiratory valve. The present study aimed to investigate LDVF-oriented exercises used in voice therapy, with the goal of examining the LDVF principle and assessing the extent to which objective vocal changes can be detected through electroglottographic (EGG) and acoustic measures in vocally healthy adults.

METHODS

In a within-subject design, 40 vocally healthy participants performed two LDVF-oriented isometric bar exercises intended to emphasize first an under-pressure (UP) thoraco-petal body activity and second an over-pressure (OP) thoraco-fugal body activity. EGG was recorded at vocal fold and at ventricular fold levels assessing contact quotient and open quotient. Acoustic measures included harmonics-to-noise-ratio, 5-point pitch-perturbation quotient, smoothed cepstral peak prominence, glottal-to-noise excitation ratio and relative fundamental frequency. Overall tests and paired comparisons were performed, and effect sizes were evaluated with Cohen's d.

RESULTS

No significant differences were found, for example, between UP- and OP-oriented exercises for both EGG measures at vocal fold or at ventricular fold levels, and no preintervention versus postintervention effects were detected (all P > 0.05, negligible to small effect sizes). Furthermore, none of the acoustic parameters showed significant UP-OP differences or pre-post effects (all P > 0.05; small effect sizes).

CONCLUSION

LDVF-oriented exercises did not produce measurable changes in EGG measures or acoustic voice quality parameters in vocally healthy adults. These findings provide no evidence for detectable LDVF principle-related effects under the present experimental conditions.