Abstract
Vocal fold vibration was observed in normal volunteers and patients with laryngeal paralysis using a laryngeal stroboscope to quantitatively evaluate the size of the glottal area. In addition, in order to evaluate vocal function, supraglottic pressure, subglottic pressure and air flow rate were simultaneously measured to determine supra-subglottic pressure difference and average glottal resistance. The subjects consisted of 12 normal volunteers and 24 patients with unilateral laryngeal paralysis (11 median fixation cases, 9 paramedian fixation cases and 4 intermediate fixation cases). For phonatory examination, the sustained vowel /e/ with easy phonation was used. In the laryngeal paralysis patients, the average glottal area was larger as the glottal position deviated from the median position. The supra-subglottic pressure difference was maintained almost constantly regardless of the average glottal area in both the normal volunteers and laryngeal paralysis patients. The average glottal area was directly proportional to the average air flow rate, and the average glottal area was inversely proportional to the average glottal resistance. The supra-subglottic pressure difference, average air flow rate and average glottal resistance of the median fixation cases without glottal closure disorders were almost the same as those of normal volunteers. However, in the median fixation cases with glottal closure disorders, the average air flow rate was higher and the average glottal resistance was lower than those of the normal volunteers.
