Source: Better Hearing Institute
A comprehensive audiologic evaluation must be completed in order to determine the types and severity of hearing loss to make appropriate recommendations for each patient. Pure tone and speech audiometry as well as the immittance test battery must be completed, in addition to any additional assessments necessary for an exhaustive profile of the hearing system. A balance test called electronystagmography (ENG) might also be needed if dizziness or imbalance is also a complaint. Some patients who are bothered by tinnitus only might have a complete tinnitus evaluation. Finally, the audiologic data provides a clinical foundation for recommendations on hearing aids and other assistive devices suitable for treating the types of hearing impairments listed below.
In general terms, there are two types of hearing loss, conductive and sensorineural. A combination of both is also seen as a mixed hearing loss. Each is discussed below.
HEARING LOSS TYPES
Conductive Hearing Loss
Conductive hearing loss is caused by any condition or disease that impedes the conveyance of sound in its mechanical form through the middle ear cavity to the inner ear. A conductive hearing loss can be the result of a blockage in the external ear canal or can be caused by any disorder that unfavorably effects the middle ear’s ability to transmit the mechanical energy to the stapes footplate. This results in reduction of one of the physical attributes of sound called intensity (loudness), so the energy reaching the inner ear is lower or less intense than that in the original stimulus. Therefore, more energy is needed for the individual with a conductive hearing loss to hear sound, but once it’s loud enough and the mechanical impediment is overcome, that ear works in a normal way. Generally, the cause of conductive hearing loss can be identified and treated resulting in a complete or partial improvement in hearing. Following the completion of medical treatment for cause of the conductive hearing loss, hearing aids are effective in correcting the remaining hearing loss.
The audiometric profile that indicates a conductive hearing loss is the presence of air-bone gaps (better hearing by bone conduction than by air conduction), excellent word recognition at a comfortable listening level, and evidence of a middle ear dysfunction on immittance. For situations where a blockage is noted in the external ear canal, hearing testing is deferred until the canal is cleared.
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