Design of a clinical vocal loading test with long-time measurement of voice.

OBJECTIVES The aim of this study was to design a clinical vocal loading task (VLT) and to track vocal loading and recovery in voice-healthy subjects. STUDY DESIGN Pilot study. METHODS Voice-healthy subjects (six female, five male) took part in a controlled VLT in the voice clinic. The VLT was designed to induce vocal fatigue. The subjects read aloud while making themselves heard through ambient speech-babble aired at 85 dB sound pressure level (SPL). Reading was terminated by the subjects when or if they felt any discomfort from the throat. The subjects wore a voice accumulator and filled out a voice activity questionnaire 1 day preceding and for 2 days following the VLT. Expert panels assessed vocal quality and laryngeal physiology from recordings. RESULTS The subjects endured the VLT for 3-30 minutes. All subjects perceived vocal loading in the VLT. All subjects raised the fundamental frequency and SPL of their speech during the VLT. No match was shown between assessment of voice quality and laryngeal physiology. The subjects showed phonation quotients of 64-82% in the task. Measurements of phonation threshold pressure (PTP) were unstable and were not used. Self-perceived vocal loading receded after 24 hours. CONCLUSIONS An authentic vocal load was simulated through the chosen method. Onset and recovery from self-perceived vocal loading was traceable through the voice activity questionnaire. The range of endurance in the VLT was an unexpected finding, indicating the complexity of vocal loading.