Experimental study of vocal–ventricular fold oscillations in voice production

Abstract

Ventricular folds are located in the supraglottal region above the vocal folds. Although the ventricular folds do not vibrate under normal vocalizations, they vibrate under certain conditions, e.g., throat singing or ventricular fold dysphonia. In throat singing, the ventricular folds vibrate at the same frequency as (or at integer ratios of) the vocal fold vibration frequency. In ventricular fold dysphonia, on the other hand, the ventricular folds interfere with the vocal folds, giving rise to a hoarse voice. In the present study, the synthetic larynx model was utilized to examine the vocal–ventricular fold oscillations. Our experiments revealed that the vocal and ventricular folds can co-oscillate at the same frequency with an out-of-phase relation. Compared to the control condition, under which no ventricular folds exist, the phonation threshold pressure was increased in the presence of the ventricular folds. Acoustic analysis indicated that jitter was reduced and vocal efficiency was increased by the ventricular folds. Distance between the vocal and ventricular folds did not alter these oscillation properties. A computational model was further simulated to elucidate the mechanism underlying the observed vocal–ventricular fold oscillations. It has been suggested that out-of-phase oscillations of the vocal and ventricular folds are important for sustaining periodic laryngeal vibrations.

Twin vocal folds as a novel evolutionary adaptation for vocal communications in lemurs

“…Because in vivo and ex vivo evidence of phonation is scarce in lemurs for methodological reasons, to examine the acoustic function of the twin vocal folds, we utilized a silicone compound model developed to study human VF vibration (Fig. 4 a, b) 32 , 33 . Such models have proven extremely useful for understanding the physiology of vocal production, since their oscillation properties have been deeply investigated and the essential features of animal vocalizations can be captured by such models 2 , 3 , 6 , 8 , 12 , 34 .…”

“…The surface is covered with a very soft superficial layer, enabling surface movement similar to the mucosal wave. The model was fabricated following the methodology of Murray and Thomson 32 and Matsumoto et al 33 . In the experiment, an airflow was injected through a pair of two MRI models (Fig.…”