Tympanometric middle-ear pressure determination with two-component admittance meters.
Exact tympanometric determination of the middle-ear pressure based on the location of the (central) extremum of susceptance, conductance, admittance, impedance, reactance or phase-angle tympanograms is not possible. None of these immittance components reaches its extremum exactly at middle-ear pressure neither at 220 nor at 660 Hz, due to the hysteresis caused by the viscoelastic behaviour of the soft biological tissue of the middle-ear structures. These effects cannot be avoided by lowering the rate of the pressure change during the recordings. The error on the middle-ear pressure determinations using a tympanometric method can be estimated to be of the order of 15 daPa.
D000158:Acoustic Impedance Tests; D000161:Acoustic Stimulation; D004432:Ear, Middle / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D011312:Pressure; D013701:Temporal Bone / Q000502:physiology; D014432:Tympanic Membrane / Q000502:physiology