Acoustic and physiologic analyses of hyperfunctional voice disorders

This study investigated the acoustic and physiologic correlates of vocal fatigue in 10 speakers with vocal nodules and 10 normal speakers in a natural environment and during an experimentally induced vocal fatigue speaking task. All subjects were examined by an otolaryngologist for the presence or absence of vocal nodules. Furthermore, experimental subjects' voices were rated as "abnormal" while the normal subjects' voices were rated as "normal" by three independent listeners.Acoustic (fundamental frequency, jitter, shimmer and signal-to-noise ratio) and physiologic (closed-to-open ratios of electroglottograph waveforms) measures were obtained for each subject over three consecutive days at three target times: "morning" or two hours after waking; "afternoon" or seven hours after waking; and "evening" or twelve hours after waking. On the fourth consecutive day two hours after waking, subjects read orally for 60 minutes using a loud voice (75-80 dB SPL at 30 cm microphone-to-mouth distance). Every twenty minutes subjects were interrupted to obtain acoustic and electroglottographic data.The results showed no significant differences between the groups regarding a pattern of change in the measures across time in a natural environment. Only fundamental frequency and signal-to-noise ratio varied from morning to evening over the three days for individual subjects in both groups. During the prolonged reading task, both groups tended to increase fundamental frequency from baseline to 60 minutes. Signal-to-noise ratio increased from baseline to 60 minutes in the experimental group, but remained relatively stable across time in the normal group. With this exception, no other differences between the groups were found regarding a pattern of change in the acoustic or physiologic measures.It was interesting that the closed-to-open ratio was the only measure that clearly differentiated the experimental from the control group. Specifically, the experimental subjects demonstrated lower closed-to-open ratios than the control subjects. The lack of significant changes over time in the voices of the two groups, or differences between them, both in a natural and controlled conditions, suggests a need to re-evaluate the traditional assumptions regarding the dynamics of vocal fatigue.U of I OnlyETDs are only available to UIUC Users without author permissio