The rate of change of fundamental frequency with respect to transglottal air pressure was determined for a single male speaker by sinusoidally varying buccal air pressure while the speaker sustained short episodes of pronation at various fundamental frequencies. The speaker phonated at two levels of “effort,” i.e., “soft” and “loud” phonation with and without auditory feedback. The sensitivity of the larynx to variations in transglottal air pressure varied from 3 to 18 Hz/cmH2O. Fundamental frequency was most sensitive to variations in transglottal air pressure at high frequencies and in the “soft” mode of phonation. The minimum transglottal air pressure for sustained phonation was 2–3 cmH2O. These results are consistent with some earlier studies and a recent theoretical model of laryngeal activity. These results further indicate that variations in subglottal air pressure and adjustments in laryngeal muscular tension both play a role in regulating fundamental frequency during normal speech.