Respiratory-laryngeal coordination in airflow conservation and reduction of respiratory efforts of phonation
Zhaoyan Zhang · The Journal of the Acoustical Society of America · 2015
Although many previous studies investigated the effects of respiratory-laryngeal coordination during voice production, the importance of respiratory-laryngeal coordination to airflow conservation and reducing respiratory efforts of phonation has not been systematically investigated. In this study, a computational model of the pressure-volume-flow relationship in the respiratory system is developed and coupled to a three-dimensional continuum model of phonation. Simulations at different conditions of the lung initiation volume and laryngeal resistance show that small laryngeal resistance, as observed in vocal fold paralysis or soft voice conditions, leads to large airflow rate out of the lungs and thus below-normal duration of speech between breaths. Although the speech duration can be increased by an increase in either the lung initiation volume or laryngeal resistance, increased laryngeal resistance also reduces the respiratory effort required to maintain a target subglottal pressure. The demand for laryngeal resistance increase in order to maintain a normal breath group duration increases when phonating at a lower lung initiation volume or when a higher subglottal pressure is desired. Finally, the simulations show that tightening vocal fold approximation is more effective than vocal fold stiffening in increasing speech duration between breaths and reducing respiratory effort of phonation. [Work supported by NIH.]