Tympanometry
Tympanometry studies certain physical characteristics of the middle and inner ear (their capacity to absorb part of the sound energy that reaches the eardrum and ossicular chain and the protective reflexes of the inner ear against loud sounds). It is of great interest for the evaluation of many diseases that affect hearing or balance.
The test is performed by means of a probe inserted into the external ear canal in a airtight manner and consisting of :
- A loudspeaker that emits a reference sound.
- A microphone that picks up sound reflected from the eardrum, ossicular chain and inner ear structures.
- A channel to vary the pressure in the external ear canal.
The measurement results are expressed as a graph with the pressure in the outer ear canal on the abscissa and the middle ear volume, admittance or absorbance on the ordinate, depending on the type of tympanogram.
The different types of tympanometric examination
In current practice, three types of examinations are performed during our hearing and balance assessments:
Conventional tympanometry at 226 Hz, which studies the physical characteristics of the middle ear (tympanum, ossicular chain, oval window)
Multi-frequency tympanometry, which analyses fluid pressure in the inner ear (endolymphatic fluid) and can detect an abnormal increase in this pressure (labyrinthine hydrops).
The search for stapedial reflexes. During intense sound stimulation, the stapedius muscle (inserted into the stapes bone) contracts to limit the transmission of sound energy to the inner ear and protect it. By identifying and measuring this reflex, we can verify the integrity of the middle ear, the inner ear, the central auditory tract and the facial nerve that causes the stapes’ muscle to contract.
In addition, our centre is equipped with an innovative Wideband tympanometry (WBT) device, which analyses middle ear absorption over a wide frequency band. Its promise is to allow a more accurate diagnosis of pathologies affecting the middle ear (tubal dysfunctions, chronic otitis, ossicular chain ruptures, otosclerosis, etc.).
Like all investigations of the auditory system, tympanometry must be part of a comprehensive examination. This includes an accurate anamnesis, examination of the ears under the microscope and subjective (tonal and vocal audiometry), and possibly objective (otoacustic emission, auditory brainstem response) hearing tests.
