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Acoustic reflex
NORMAL
For screening purposes, an ipsilateral or contralateral reflex measured at any one of the levels
available per frequency can be considered normal. Obviously, the lowest values are desired. However,
without knowing the hearing threshold level of the individual per frequency, it is difficult to make a
more definite statement. Generally speaking, the reflex is reported to occur at between 70 and 90 dB
HL above the hearing threshold in patients with normal hearing. Remember that these values apply
to reflex threshold measurements and that this instrument does not permit reflex threshold
measurements due to the use of a hand-held probe. The presence of a reflex in the absence of a
compliance peak suggests that the tympanometric results should be considered invalid and the test
repeated. This is true because if there is no compliance measured during tympanometry, it is not
possible to measure any stiffening affect during the reflex stimulus presentation.
ABNORMAL
If a pressure leak occurs during the reflex testing and the pressure system is unable to correct for this
leak, the reflex test sequence is aborted. When this occurs, the test results are assigned the letters NT
(Not Tested).
If no response is obtained at the third and final stimulus level, the instrument will indicate this with
the letters NR or No. More detailed testing at the frequency where this occurred is required to
determine the reason for the no response.
Audiometry
NORMAL
A normal response from a child should be at or below 20 dB HL. A normal response from an adult is
at or below 25 dB HL. Remember that these normal values assume a quiet environment during testing.
ABNORMAL
In children, a failure to respond to a 20 dB HL (or lower) stimulus presentation during a retest
performed four to six weeks after the initial test would indicate the need for more extensive diagnostic
testing to determine the cause.
In adults, a failure to respond at or below 25 dB HL when the room noise levels are low indicates the
need for more evaluation. However, the age and employment history of the individual must also be
considered.
