Ear Pressure (PCS1, PCS2, PMBC¹, PCS3)

Participant ear pressure was measured on both right and left sides using a hand-held middle ear analyzer (Titan, Interacoustics A/S, Assens, Denmark). The instrument sends out a sound signal and measures the energy that is returned while the pressure in the ear canal is varied from +200 to -400 decapascals (daPa).  Under normal conditions, pressure in the middle ear should be equal to atmospheric (0 daPA).  The returned sound is at a minimum when the eardrum is in its resting position (middle ear pressure = ambient pressure) because most of the sound is transmitted to the inner ear (normal hearing).  The applied pressure at which the returned sound is minimal is considered to be a measure of the middle ear pressure because it is the pressure required to move the eardrum to its normal position (middle ear pressure = ear canal pressure).  If there is no change in returned sound over the pressure range, the eardrum is not moving in response to the pressures, and this could indicate fluid in the middle ear, i.e., otitis media.  Extreme negative pressures usually indicate an improperly functioning Eustachian tube, which can be a consequence of having a cold.

¹ PMBC ear pressure data are not available for trials 3 (n = 12) and 7 (n = 14).

Reference

Doyle, W. J., Winther, B., & Alper, C. M. (2008). Daily tympanometry for high-resolution measurement of the time between onset of cold-like illness and middle ear effusion.  Laryngoscope, 118(6), 1066-1071.