Healthy Hearing Program - Special Olympics

ABNORMAL
A compliance values of less then 0.2 cm3 indicates a pathological condition, as the middle-ear system
is stiffer than normal. To distinguish the probable cause of the stiffening, the pressure value where this
stiffened compliance peak occurs is necessary. For example, normal pressure along with a stiff middleear
system is indicative of a “glue-ear”, otosclerosis, a severely scarred tympanic membrane, or a layer
of plaque across the tympanic membrane. On the other hand, abnormal pressure along with a stiff
middle-ear system is consistent with a poorly functioning Eustachian tube with possible effusion
(i.e., serous otitis mediate) within the middle ear.
NOTE
If the measured “peak” compliance value is less than 0.1 cm3, the GSI 37 may
not display any indicator arrows on the compliance and pressure axes, although a
shallow peak may be detectable on the display. If this tympanogram is printed, the
letters NP will appear in place of the peak compliance and pressure values indiciating
that no peak was detected. Also in this instance, no gradient will be calculated,
so three dashes (− − −) will appear under GR on the display.
A compliance value greater than 1.8 cm3 generally indicates a hyperflacid middle-ear system.
Such a condition could be due to some moderate scarring on the tympanic membrane. However,
if the compliance is greater than 3.0 cm3, this may be indicative of a disarticulated ossicular chain.
Further testing may be necessary to confirm this condition.
NOTE
The validity of tympanometry is dependent upon a healthy tympanic membrane. A
pathological condition at this membrane can mask the true condition of the middle
ear.
4.3 PRESSURE PEAK
NORMAL
Strict rules for normal middle-ear pressure indicate a normal range of ± 50 daPa. However, for most
applications, a normal pressure range of -150 daPa to +100 daPa is used.
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