Temperature changes in the human middle ear were investigated during surgery. I examined four ears of subjects with facial nerve palsy and three ears of subjects with chronic otitis media. Microthermistors were positioned in the external ear canal, lateral semicircular canal, and attic. Following water irrigation (30°C and 20°C), I recorded the resistance of the thermistor by video-tape recorder and then converted the readings to temperature. The mean maximum temperature change in the lateral semicircular canal was -0.70°C at 30°C stimulation (58 seconds after irrigation) and -1.59°C at 20°C stimulation (62 seconds after irrigation). The degree of mastoid pneumatization seemed unrelated to the maximum temperature change in the lateral semicircular canal. I made a onedimensional mathematical model of thermal conduction and compared it with the measured data, but the model was incomplete.
