Vertical laryngeal position during continuous and discrete vocal frequency change.

Six young adult male subjects produced sustained phonation throughout their vocal frequency ranges: first, in a glissando or continuous frequency change maneuver, and second, in discrete intervals at separate trials. Measures of intrinsic and extrinsic laryngeal muscle activity and vertical laryngeal position were related to voice fundamental frequency in the two conditions. Each subject consistently positioned his larynx at a resting level when he was instructed to relax or when he was not performing experimental tasks. All larynx positions during experimental tasks were measured as deviations from this resting level. Subjects showed a close correspondence between their vertical laryngeal positions and voice frequencies--more so for the glissando maneuver than for changes in discrete frequency tasks. In general, subjects lowered their larynges from the resting position for low-frequency phonation and raised their larynges for higher fundamental frequencies. Absolute larynx position for the same frequency was quite varied both within and between subjects. Vertical laryngeal position during phonation most often was directly related to the activity of the thyrohyoid and sternothyroid muscles. Neither vertical laryngeal movement nor intrinsic laryngeal activity showed any pattern of relationship to changes between modal and falsetto voice registers.