Perceptual DistortionOtoacoustic Emissions, SpontaneousPositron-Emission TomographyTomography, Emission-ComputedReproducibility of ResultsVehicle EmissionsFluorodeoxyglucose F18RadiopharmaceuticalsTomography, Emission-Computed, Single-PhotonSpectrometry, FluorescenceSensitivity and SpecificityFluorine RadioisotopesTime FactorsGreenhouse Effect