The fundamental frequency of phonation (F0) change per unit change in transglottal pressure (dF/dP) was studied at different extension lengths and masses of the vibrating part of a rubber model. The dF/dP was decreased when the vibrating part was extended, and also when the mass of the vibrating part was increased. In the former, the F0 was increased, and in the latter, the F0 was decreased. In humans, we have noticed that when the F0 was increased, the dF/dP first decreased and then increased, taking a V-shaped curve as a function of the F0. The present study reveals the mechanism underlying the V-shaped curve observed in humans.