I was required to collect some data to present my understanding of Tympanometry:
examination used to test….
- the condition of the middle ear and
- mobility of the eardrum (tympanic membrane)
- conduction bones by creating variations of air pressure in the ear canal.
Tympanometry is test of middle-ear function. not a hearing test, but rather a measure of energy transmission through the middle ear.
The test should not be used to assess the sensitivity of hearing and the results of this test should always be viewed in conjunction with pure tone audiometry.
tympanometry permits a distinction between sensorineural and conductive hearing loss
tympanometry can be helpful in making the diagnosis of otitis media by demonstrating the presence of a middle ear effusion.
How it works:
- A tone of 226 Hz is generated by the tympanometer into the ear canal
- sound strikes the tympanic membrane, causing vibration of the middle ear which results in the conscious perception of hearing.
- Some of this sound is reflected back and picked up by the instrument.
- Most middle ear problems result in stiffening of the middle ear, which causes more of the sound to be reflected back.
Admittance is how energy is transmitted through the middle ear. The instrument measures the reflected sound and expresses it as an admittance or compliance, plotting the results on a chart known as a tympanogram.
Normally, the air pressure in the ear canal is the same as ambient pressure. Under normal conditions, the air pressure in the middle ear is approximately the same as ambient pressure since the eustachian tube opens periodically to ventilate the middle ear and to equalize pressure. In a healthy individual, the maximum sound is transmitted through the middle ear when the ambient air pressure in the ear canal is equal to the pressure in the middle ear.
Procedure
After an otoscopy (examination of the ear with an otoscope) to ensure that the path to the eardrum is clear and that there is no perforation, the test is performed by inserting the tympanometer probe in the ear canal. The instrument changes the pressure in the ear, generates a pure tone, and measures the eardrum responses to the sound at different pressures. This produces a series of data measuring how admittance varies with pressure, which is plotted as a tympanogram
- Type A tympanogram (NORMAL) There is a normal pressure in the middle ear with normal mobility of the eardrum and the conduction bones.
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Type B & C tympanograms - reveal fluid in the middle ear, perforation of the tympanic membrane, scarring of the tympanic membrane, lack of contact between the conduction bones of the middle ear or a tumor in the middle ear.
The categorising of tympanometric data should not be used as a diagnostic indicator. It is merely a description of shape.
