Intrasubject variability of objective voice measures.

Recent advances in the diagnosis and treatment of voice disorders necessitate the need for accurate and reliable objective voice measurements. There are many instruments commonly used to analyze voice data. Many, if not most, of these instruments have not been adequately tested for reliability or consistency. This study evaluates the intrasubject variability of the objective voice measurements from two commonly used voice analysis instruments. The study also presents data correlating subjective mood states, room temperatures, sleep times of the subject, time since last meal, and hydration levels to the various acoustic measures. Several weak but significant correlations were obtained and are discussed. Guidelines for the appropriate use of these instruments are described.