Preliminary Study of the Open Quotient in an Ex Vivo Perfused Human Larynx

Abstract

Importance Scientific understanding human voice production to date is a product of indirect investigations including animal models, cadaveric tissue study, or computational modeling. Due to its invasive nature, direct experimentation of human voice production has previously not been possible. The feasibility of an ex-vivo perfused human phonatory model has recently allowed systematic investigation in virtually living human larynges with parametric laryngeal muscle stimulation. Objective In this study, the relationship between adductor muscle group stimulation and the open quotient (OQ) of vocal fold vibration was investigated using an ex-vivo perfused human larynx. Design Human perfused tissue study. Setting Physiology Laboratory. Participants Human larynx is recovered from research-consented organ donors within two hours of cardiac death. Interventions, Main Outcomes and Measures Perfusion with donated human blood is re-established shortly after cardiac death. Human perfused phonation is achieved by providing subglottal airflow under graded neuromuscular electrical stimulation bilaterally to the intrinsic adductor groups and cricothyroid muscles. The phonation resulting from the graded states of neuromuscular stimulations are evaluated through high-speed vibratory imaging. OQ is derived through digital kymography and glottal area waveform analysis. Results Under constant glottal flow, step-wise increase in adductor muscle group stimulation decreased OQ. Quantitatively, OQ values reached a lower limit of 0.42. Increased stimulation above maximal muscle deformation was unable to affect OQ beyond this lower limit. Conclusions and Relevance For the first time in a neuromuscularly activated human larynx, a negative relationship between adductor muscle group stimulation and phonatory OQ was demonstrated. Further experience with the ex-vivo perfused human phonatory model will work to systematically define this causal relationship.

3D-FV-FE Aeroacoustic Larynx Model for Investigation of Functional Based Voice Disorders

“…Open Quotient (OQ) [a.u.] 0.37-1.00 (Holmberg et al, 1988;Baken and Orlikoff, 2000) 0.42-1.00 (Mendelsohn et al, 2015) 0.93 0.93…”

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“…The differences in the point fields can in part be explained by the fact that the DEGG method is more dependent on a highly stable and simple EGG signal. This is caused by the because there are many factors including interglottal mucus and irregular vibration of vocal cords which affect the relationship between the DEGG and glottal closure [12][13][14][15][16][17]. In comparison, the neural network is better able to identify and predict the position of the opening and closing of the glottis because it is better able to filter the irregularities in the EGG signal from the HSV training.…”

Combining Artificial Intelligence and Automatic Analysis to Study of the Closure Characteristics of Healthy Human Vocal Cords during Phonation Using Synchronous Electroglottography and Laryngeal High-Speed Videoendoscopy

“…The differences in the point fields can in part be explained by the fact that the DEGG method is more dependent on a highly stable and simple EGG signal. This is caused by the because there are many factors including interglottal mucus and irregular vibration of vocal cords which affect the relationship between the DEGG and glottal closure [12][13][14][15][16][17]. In comparison, the neural network is better able to identify and predict the position of the opening and closing of the glottis because it is better able to filter the irregularities in the EGG signal from the HSV training.…”