Relationship between transglottal pressure and fundamental frequency of phonation, with effects of dehydration produced by atropine, in healthy volunteers.

We investigated the effects of the intravenous injection of atropine sulfate on the relationship between the fundamental frequency of phonation (F0) and the magnitude of F0 change per unit change in transglottal pressure (dF/dP) in 4 healthy male volunteers. Before the injection of atropine, we observed a nonlinear or V-shaped relationship between dF/dP and F0. After the injection, the values for dF/dP were reduced at a lower F0, whereas the values were unchanged at a higher F0. The results support our hypothesis that the relationship between dF/dP and F0 reflects adjustments in the length and depth of the vocal folds in controlling F0.