A PRESSURE-REGULATED MODEL OF NORMAL AND PATHOLOGICAL PHONATION

Recent evidence suggests that the lung-thorax system functions as a co nstant pressure source during phonation. However, previous animal mode ls used a constant flow source. This article describes an in vivo cani ne model that maintains a constant subglottic pressure during phonatio n to more closely simulate the pulmonary system. At any given subglott ic pressure, increasing levels of recurrent laryngeal nerve stimulatio n resulted in a significant rise in resistance followed by a plateau. Increasing levels of superior laryngeal nerve stimulation, however, pr oduced no significant change in glottal resistance. Three experimental conditions were studied: normal, unilateral recurrent laryngeal nerve paralysis, and paralysis followed by arytenoid adduction. In normal c anines, maximal vocal efficiency values were the highest, indicating t he best match between pressure and resistance. The vocal efficiency va lues were significantly lower in recurrent laryngeal nerve paralysis, indicating pressure-resistance mismatch. Arytenoid adduction increased the maximal vocal efficiency values and decreased the mismatch observ ed in the paralyzed state. These findings may provide insight into an understanding of normal and pathologic laryngeal behavior.