Influence of lung volume on the airflow-intensity relationship.

This study reports airflow-intensity relationships observed in crescendo and decrescendo phonations produced at three fundamental frequency levels by 10 men. The purpose of the investigation was to study the possible influence of lung volume on airflow-intensity relationships. Of the 30 decrescendo phonations, 26 showed statistically significant correlation coefficients and none showed significant negative correlations. The crescendo phonations, however, showed greater inter- and intrasubject variability. Of the 30 crescendo phonations, 16 showed statistically significant positive correlation coefficients and 6 showed significant negative correlations. Because lung inflation varied directly with intensity in the decrescendo task and indirectly in the crescendo task, it was concluded that lung volume does influence the consistency and strength of relationship between airflow and intensity. The findings are discussed in terms of the influence of lung volume on the relative contributions of glottal resistance and expiratory force to the regulation of subglottal pressure.