PROBLEMS OF VOICE COMMUNICATION IN THE NAVY: Regulation of Vocal Intensity at Low Fundamental Frequencies

Previous investigations indicate that as one approaches, the upper or lower limits of the modal or falsetto phonational registers, the range of vocal intensities the speaker is capable of producing decreases. However, no data are available relating frequency/ intensity changes for extremely low frequency phonation, often called glottal or vocal fry due to its perceptual attributes. The purpose of this study was to determine the relationship between fundamental frequency and vocal intensity during low frequency phonation. Subjects sustained the low frequency pulse-like phonation for three seconds at three points in their total low frequency range and the intensity recorded. Thereafter, the subjects sustained glottal fry at the three recorded intensities previously obtained and the fundamental frequency recorded. The findings indicate that glottal fry is produced at low intensities in relation to intensity levels noted by previous investigators for the modal and falsetto registers. Furthermore, it appears that frequency and intensity changes for normally sustained low frequency phonation are inter-dependent. Finally, combined results of this and previous studies indicate that the predominant frequency/intensity changing mechanism for this normal but low frequency phonation is siibglottal air pressure.