Immittance Audiometry

Middle Ear Magic: Uncovering the Secrets of Your Hearing with Immittance Audiometry

Immittance Audiometry is a test used to assess the middle ear’s function and the mobility of the eardrum. It helps in evaluating how well sound is transmitted through the ear canal to the inner ear. This test is primarily used to diagnose conditions affecting the middle ear, such as fluid in the ear, ear infections, or Eustachian tube dysfunction.

Key Components of Immittance Audiometry:

• Tympanometry:

  • Measures the movement of the eardrum in response to air pressure variations in the ear canal. It helps determine if the eardrum is functioning properly or if there is a blockage or fluid in the middle ear.
  • The test involves placing a probe in the ear, which changes the air pressure and records how well the eardrum moves. Abnormal results could indicate middle ear problems like fluid buildup, perforated eardrum, or eustachian tube dysfunction.

• Acoustic Reflex Testing:

  • Assesses the contraction of the middle ear muscles (stapedius and tensor tympani) in response to loud sounds. This reflex helps protect the inner ear from loud noises.
  • The test measures the reflex pathway from the ear to the brainstem and back. An absent or abnormal reflex could suggest a problem in the auditory nerve, brainstem, or middle ear.

• Static Compliance:

  • Measures the movement of the eardrum when pressure in the ear canal is varied. This helps assess the flexibility of the eardrum, which can be reduced by conditions like otitis media or a perforated eardrum.

How the Test Is Conducted:

• A small probe is placed into the ear canal.
• The probe generates a series of air pressure changes and measures the ear canal’s response.
• The audiologist may also emit sound stimuli to trigger the acoustic reflex and measure the response from the middle ear muscles.

Why It’s Done:

Immittance audiometry is useful for diagnosing:

• Middle ear fluid (e.g., otitis media)
• Eustachian tube dysfunction
• Perforated eardrum
• Hearing loss due to middle ear problems
• Evaluation of ear drum mobility (e.g., in cases of otosclerosis or other structural abnormalities)

After the Test:

• The results will help determine if there is a middle ear problem affecting hearing.
• Based on findings, the audiologist or ENT specialist will recommend further treatments, such as medications for infections, surgery for structural issues, or hearing aids for hearing loss caused by middle ear dysfunction.

Immittance audiometry provides valuable information for diagnosing non-sensorineural causes of hearing loss and is commonly used alongside pure-tone audiometry and speech audiometry to assess hearing health comprehensively.