Introduction: Vocal loading tasks (VLTs) help researchers gather acoustic measurements and understand how a healthy speaker adjusts their voice in response to challenges. There is a dearth of evidence measuring the impact of speaking rate in VLTs on acoustic voice parameters and vocal fatigue.
Objectives: In the present study, the relationships between acoustic voice parameters and self-reported vocal fatigue were examined through an experimental VLT.
Methods: 38 students completed a 45-minute VLT which involved the recording of three randomized reading tasks. The tasks varied by the speed in which the words were presented (slow, medium, fast) on a computer monitor. Vocal fatigue ratings were measured subjectively using a Borg scale and negative adaptations to vocal loading were measured objectively using Sound Pressure Level (SPL, in dBA), fundamental frequency (fo, in semitones), and phonation time (Dt %).
Results: Analysis indicated that vocal fatigue increases with time, and the slope of this relationship is affected by the speaking rate. SPL and fo increased with speaking rate and the standard deviation of SPL and fo decreased with speaking rate. On average, the male participants' phonation time values were 7.8% lower than the female participants. The rate of increase of vocal fatigue with time during the experiment was higher in the fast speaking style compared to the slow and medium ones.
Conclusion: The results provide support that the novel VLT altered multiple vocal parameters to induce measurable changes in vocal fatigue.
Keywords: Phonation time; Speaking rate; Speech acoustics; Vocal effort; Vocal loading.
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