COMPARISON OF DIRECT AND INDIRECT CALCULATIONS OF LARYNGEAL AIRWAY-RESISTANCE IN VARIOUS VOICING CONDITIONS

Calculation of laryngeal airway resistance using intraoral pressure di vided by airflow has become a widely accepted clinical tool. The estim ation is based largely on theoretical assumptions, particularly regard ing the relationship between intraoral and subglottal pressure. To det ermine the estimate's validity, direct measures of airflow and subglot tal, intraoral and pharyngeal pressures were obtained for four men and four women. Subjects produced normal, loud, soft and simulated breath y and strained syllable trains. Comparison of direct and indirect calc ulations of laryngeal airway resistance revealed generally good corres pondence, particularly for [pi] syllables, although the estimate's acc uracy varied among individual subjects. Some interpretive caution is w arranted for the extremes of laryngeal airway resistance, with resista nce likely to be underestimated in the strained condition, and overest imated in the breathy condition.