The examination of the patient’s ears to prepare for tympanometry is important and the probe should be pointed in the direction of the tympanic membrane. The probe frequency for the routine measurements is 226 Hz and the tracking in the normal should be done at 200 data which must be stopped once the peak is recorded. It is also suggested that a repetition of the test should be conducted in its entirety if an unexpected result is obtained and the probe tip be cleaned after the completion of tympanometry. Though there is no consensus on standard normal values for middle ear pressure and admittance, a mean value of zero may be fixed for middle ear pressure and the range between 0.3 to 1.6 with a mean of 0.7 for middle ear admittance or compliance.
Tympanometric measurements require the acoustic properties of the ear canal and the application of air pressure in tympanometry distinguish the carnal and middle ear components. The technical note also gives details about acoustic reflex measurements and, accordingly, there are facilities in impedance/admittance instruments to provide acoustic stimulus to the ear and to detect the associated reflex. The reflex measurements are usually made at a pressure corresponding to the tympanometric peak. Tympanometry and other instruments are then applied to the evaluation of Eustachian tube function. “Tympanometric results do not identify pathology uniquely and should be interpreted in the context of other information… Report forms should include normal values as an aid to interpretation.” (Technical note, 257)