Subjects will be recruited who only experience symptoms or present signs interpretable as Eustachian (ET) dysfunction (ETD) when exposed to rapid changes in ambient pressure as, for example, during flights in airplanes (in the absence of a concurrent cold/active nasal allergy) or during free and tanked diving. In general, subjects presenting to physicians with these conditions are diagnosed with poor ET function (ETF) based solely on symptom/sign presentation. However, it is not known how to identify those persons who will experience these symptoms/signs at a future time which is the goal of this study or how to prevent those presentations in susceptible individuals. To calibrate the test protocol, 20 subjects/age ranges of 10-19, 20-29 and 30-50 years (total=60 control subjects) who are in good health, fly and/or dive frequently but report no ear-related problems on ascent or descent, will be recruited. One hundred fifty symptomatic subjects in general good health aged 10 to 50 years with the lower age limit chosen to assure good communication between the subject and investigators, will also be recruited. These and the control subjects will have intact tympanic membranes since subjects with non-intact tympanic membranes do not experience barotrauma but maintain ambient middle-ear (ME) pressures throughout a flight.