−47− Synthesiology English edition Vol.1 No.1 (2008) In the 1990s, a U.S. company developed a new infrared clinical thermometer in which measurement was taken by inserting the sensor probe into the ear canal (hereinafter will be called “ear thermometer”), and was marketed in the United States and Europe. Figure 1 shows the external appearance of ear thermometers and the schematic diagram of the...