Does temperature effect tympanometric evaluation of ear canal volume? A scientific study using an Ear Canal Model.

Tympanometric evaluation is a routine part of the complete otological examination. Although tympanometry when performed in standard conditions is known to accurately and precisely assess ear canal volume, the effects of variation in temperature have not been reported upon. This study examines the effect of temperature on the capability of the tympanometer to accurately evaluate external auditory canal volume in both simple and partially obstructed Ear Canal Models. An Ear Canal Model was designed using simple laboratory equipment including a 5 ml calibrated clinical syringe. This was attached to the sensing probe of a Kamplex tympanometer. Two basic trials were undertaken: (a) evaluation of the effect of temperature on the tympanometer in simple canal volume measurement and (b) assessing canal volume with partial canal occlusion. These studies were conducted at 0, 10, 20 and 30 °C in a Thermotron climatic chamber. 1,400 individual test scenarios were completed over the two arms of the study. At volumes of 1.4 cm(3) or below, tympanometry had a very high level of correlation (Spearman's ρ = 1) with the actual volume present at all tested temperatures except 0 °C. There was no significant relationship between temperature and degree of error in ear canal volume measurement in both simple and partially occluded models. The ability of the Kamplex tympanometer to accurately and precisely assess ear canal volume in this scientific model in both simple and partially occluded scenarios up to a volume of 1.4 cm(3) is not effected by ambient temperature. These findings suggest the Kamplex tympanometer could be used as an effective objective tool in both laboratory and human models of the external auditory canal.