A comparison of two methods for determining middle ear malfunction
Acoustic impedance testing is an objective method for determining middle ear function. Such an aid to diagnosis of middle ear pathology and application to clinical audiology was first realized by Metz (1946).Acoustic impedance measures the opposition encountered by an acoustic wave. When a sourxd is introduced to the external auditory meatus one can measure the opposition that exists at the lateral surface of the tympanic membrane or at some plane within the external auditory meatus. These clinical acoustic impedance measurements may be classified as either static or dynamic. Static acoustic impedance measurements are made with ambient air pressure within the external auditory meatus, while dynamic measurements are made when the air pressure is varied within the external auditory meatus. Dynamic measurements basically describe the mobility of the tympanic membrane; by knowing the mobility of the tympanic membrane one can determine the function of the middle ear.Tympanic membrane mobility can also be determined by otoscopic examination, using a Siegle otoscope. The physician varies the air pressure within the external auditory meatus by squeezing on a bulb that is attached to the otoscope. The tympanic membrane moves as the air pressure is varied. Middle ear function is then determined by the amount of mobility.The purpose of this study will be to compare two methods far determining middle ear malfunction: acoustic impedance measurement and otoscopic examination. This will be done by testing patients with middle ear pathologies using both methods and comparing the test results with the surgically-confirmed results.