Influence of Forced Transglottal Pressure Changes on Vocal Fundamental Frequency

Abstract

Forced transglottal pressure changes (ΔPt) were produced in 10 subjects while they sustained vowels and uttered monosyllables. Pressure changes were applied sinusoidally at both the body surface (subglottally) and the airway opening (supraglottally) by loudspeakers driven at 4–6 Hz (the empirically determined resonant frequency of each subject). Vocal fundamental frequency (f0) was recorded with a throat microphone and analyzed from narrow-band spectrograms. Results showed values for (Δf0/ΔPt) to be dependent upon vocal frequency, intensity, and register, and to be independent of vowel, voice quality, utterance type (i.e., sustained vowels versus vowels in syllables), and mode of applying pressure. Except for falsetto phonations, (Δf0/ΔPt) values exceeded 5 Hz/cm H2O in only one subject and in the speech range of f0 they were typically 2–4 Hz/cm H2O. These findings fail to support earlier work (Lieberman et al., 1969) based on one of the subjects included here. We conclude that f0 changes characteristic of conversational speech can be accounted for only in part on the basis of changes in (Pt) and that significant control of f0 is vested in laryngeal adjustments.