What type of thermometer is commonly used in the ear canal?

The type of thermometer commonly used in the ear canal is known as a tympanic thermometer. This device is specifically designed to measure the temperature inside the ear, which can provide a quick and accurate assessment of a person's body temperature. The tympanic thermometer works by detecting the infrared heat emitted by the eardrum and surrounding tissue, making it a convenient option for both clinical and home use.

Other types of thermometers, such as digital and aural thermometers, may serve similar functions but are not specifically tailored for ear use. A digital thermometer typically takes readings orally, rectally, or axillary, while an aural thermometer is a broader term that can include both tympanic thermometers and other types of ear-based measurement devices. Rectal thermometers are primarily used in clinical settings for precise measurements, especially in infants, but are not applicable for ear canal measurement. Hence, the specificity and design of a tympanic thermometer make it the correct choice for this question.