Measurement of core temperature remains a significant problem, especially in hypothermic i\environments. Oral temperature readings are inaccurate and inappropriate for some types of patients. Rectal temperatures also often do not reflect true core temperature readings, are often considered invasive, and are inappropriate in cold environments. Esophageal readings are at time difficult to obtain and sensitive to the precise placement of the thermistor. In contrast, tympanic membrane temperatures have been reported to accurately reflect core temperatures in steady state conditions and to rapidly adapt during dynamic changes in core temperature. This application proposes to evaluate the limitations of tympanic membrane temperature in regard to its ability to reflect core temperature in extreme hypothermic conditions and to design technology such that the tympanic membrane temperature can be monitored remotely, thus eliminating the danger of tympanic membrane damage due to direct thermal sensing. If this phase I feasibility study proves to be productive, phase II efforts will center on the design of a portable unit which can quickly and effectively monitor core temperature in a wide range of environmental conditions.