Audiologic Testing for Hearing Loss
Audiometry (Hearing Test)
The main purpose of a hearing test is to determine the degree, configuration and type of hearing
loss. The results of the test are recorded on an audiogram, a graphic chart of hearing results.
Results from your audiometric evaluation will help determine the nature of hearing loss
(conductive vs. mixed) and if one or both ears are affected. Testing is completed pre-operatively
as well as post-operatively. Otosclerosis typically causes one of the following:
- Conductive hearing loss is caused due to lack of sound transmission through the middle ear and hearing bones. Otosclerosis causes poor movement, or fixation, in the 3 rd hearing bone, the stapes bone. The immobility of the stapes bone causes the conductive hearing loss.
- Mixed hearing loss is a combination of conductive hearing loss and sensorineural hearing loss (damaged inner ear and/or auditory nerve function).
Otosclerosis can affect the inner ear as well and this process can cause sensorineural hearing loss in addition to the conductive hearing loss, thus
causing a mixed hearing loss.
The specific type of hearing loss will dictate management options and can be determined by
detailed hearing tests.
Tympanometry (Acoustic Immittance testing)
Acoustic Reflex Thresholds (ARTs)
Acoustic Reflex Thresholds assessment takes a deeper look at middle ear function, specifically involving the contraction of the stapedius muscle. The stapedius muscle is the smallest muscle in your body that connect to the the stapes bone. This muscle contracts and stiffens the stapes bone and the eardrum in response to louder sounds, thus serving to protect our inner ear when we are exposed to loud sudden sounds. The acoustic reflex pathway involves both the sensory and motor pathways of the 7th and 8th cranial nerves. At the Center for Otosclerosis, we check ART to assess the reflex pathway. In otosclerosis, the reflex pathway is not active because the stapes bone is already immobile, thus not allowing the stapedius muscle to contract and limit the motion of the stapes bone as it should in normal ears. Performing this test allows us to further confirm the diagnosis of otosclerosis.
