Immittance audiometry generally consists of three separate tests:
tympanometry, acoustic reflex thresholds, and reflex decay.
Tympanometry is an objective test used to evaluate the movement of
the eardrum and status of the middle ear.
In acoustic reflex testing, the audiologist measures slight changes
in the eardrum because of two muscles in the middle ear (stapedius and
tensor tympani muscle) that automatically contract to loud sounds.
The softest level at which these muscles contract is noted at several
pitches. This level is measured in two ways at each pitch:
1)ipsilaterally - stimulate one ear and measure the changes in the
same ear, and 2)contralaterally - stimulate one ear and measure the
changes in the opposite ear. This test allows the audiologist to
help determine if the hearing loss is conductive or sensorineural.
In the reflex decay test, a loud tone is presented for 10 seconds
and the changes in the eardrum are again monitored during this period
as the stapedius muscle contracts. The results of this test can
allow the audiologist to determine if the hearing loss is related to
problems in the cochlea or the acoustic nerve. This testing may also be done
contralaterally or ipsilaterally.
Information obtained from immittance audiometry
can offer insight into pathologies of the middle and inner ear.
Back to Audiology Services Page