Are voice endurance tests able to assess vocal fatigue?

Voice endurance tests are often used to evaluate vocal fatigue or to test the suitability of an individual for voice demands. It is assumed that these tests help to identify subjects with laryngeal or vocal fatigue out of a population of persons with complaints of discomfort in the throat, recurrent hoarseness and decreased voice power. In this study we evaluated the Voice Interval Test with respect to its discriminative power by comparison of voice performances in 20 patients with a history of vocal fatigue with that in 12 healthy subjects. Voice performance was studied during the Voice Interval Test as well as during regular use of the voice on a working day by electroglottography (EGG), acoustic analysis and a self-rating scale for pain and fatigue. Despite the number of tests the data did not reveal any significant difference between the patients and the healthy subjects. Voice fatigue could therefore not be identified and the clinical relevance of the Voice Interval Test appears to be questionable.