The purpose of the study, Effects of Interaction of Caffeine and Hydration on Voice Performance, is to gather information about the effects of caffeine and hydration upon voice performance. The research question involves whether systemic hydration may reduce degradation on voice performance caused by caffeine ingestion. It is hypothesized that the hydration conditions will result in a less degraded vocal performance as compared with the nonhydration condition.The investigation involves abstention from any caffeine ingestion for 24 hours - from 8pm the day before testing to 8am the morning of testing. In addition, preparation for participation involves abstaining from ingesting any foods and liquids for 12 hours - from 8pm to 8am of the following morning. Each test will take about 10 minutes.

The objective of this investigation is to explore the interaction of water and caffeine on voice performance through (a) acoustic measures of voice, and (b) aerodynamic measurements (minimum lung pressure required to initiate phonation. The acoustic and aerodynamic measurements were selected for this study in an effort to demonstrate the effects of four levels of hydration and caffeine status on voice quality: 1) caffeine and water1 (i.e.., Experimental Group 1 - ingestion of 200 mg of caffeine in conjunction with 500 ml of water), 2) caffeine and water2 (i.e., Experimental Group 2 - ingestion of 200 mg of caffeine in conjunction with 1.0 liter of water), 3)caffeine only (i.e., Experimental Group 3: ingestion of 200 mg of caffeine and no water), and 4) control (i.e. no ingestion of caffeine or water). The research question involves whether systemic hydration may reduce degradation on voice performance caused by caffeine ingestion. It is hypothesized that the hydration conditions will result in a less degraded vocal performance as compared with the nonhydration condition. Additionally, it is hypothesized that ingestion of 1.0 liter of water will have a greater effect on voice performance than ingestion of 500 ml of water. An additional objective of this study is to increase scientific knowledge of voice functioning by providing further data about the effect of the interaction of water and caffeine on voice performance. The results of this project may be a valuable addition to the scientific literature in vocology, and may also contribute to prevention plans for minimizing vocal disturbances. Therefore, vocational programs may include vocal prevention directions based on this study. In addition, knowledge about prevention of voice disorders may be included in the academic curriculum of students enrolled in training programs for professions involving substantial voice use.

Inclusion Criteria:

• Healthy individuals, ranging from 18 to 35 years of age.

Exclusion Criteria:

• History of voice disorders, history of coronary disease, history of high blood pressure.