Tympanogram Characteristics
Figure 24 illustrates a MicroTymp2 tympanogram. A description of the key
characteristics of the tympanogram follows.
Figure 24
Static Admittance (Peak Ya) is a measure of the height of the tym-
panometric peak. Given appropriate normative values, static admittance
is a useful indicator of middle ear disease.
Tympanometric Gradient (GR), or tympanometric width, is a measure
of the width of the tympanometric peak. Defined as the width of the tym-
panogram (in decapascals) at 50% of peak eardrum admittance, tympan-
ometric width is a good indicator of the presence of middle ear effusion.
Tympanometric Peak Pressure (TPP) is the position of the tympano-
metric peak on the pressure axis. TPP is an imprecise measure of the
middle ear pressure. By itself, TPP is not an accurate indicator of middle
ear disease.
Equivalent Ear Canal Volume (+200 Vea) is the admittance value
determined with an ear canal air pressure of +200 daPa (decapascals).
A flat tympanogram with an abnormally-high equivalent ear canal volume
suggests the presence of a tympanic membrane perforation or a patent
tympanostomy tube.
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