Hearing loss can be divided into three basic types: conductive, sensorineural and mixed hearing loss.
Conductive hearing loss
This type of hearing loss is caused by anything that interferes with the transmission of sound to the inner ear. Sound travels from the environment to the outer ear (visible part of the ear and the ear canal) to the middle ear (the eardrum and the three little bones inside the middle ear) and on towards the inner ear. If there is a breakdown in this chain of transmission, sound cannot reach the inner ear and cannot be transferred to the brain for interpretation. This type of hearing loss can usually be successfully treated medically or with surgery. If treated early and correctly, this type of hearing loss can be non-permanent but if left untreated or not treated correctly, it can cause a permanent hearing loss. A conductive hearing loss does not necessarily affect both ears. Should the person still need amplification after treatment, they can benefit greatly from an assistive device (like a hearing aid).
Sensorineural hearing loss
When one has a sensorineural hearing loss, the cause is due to damage to the inner ear and / or the acoustic nerve. The inner ear consists of the cochlea and the acoustic nerve that transmits sound to the brain for interpretation. If the hair cells inside the cochlea are damaged, they are unable to respond to sound. In turn, the sound then cannot be transmitted to the acoustic nerve that connects them to the brain. Sensorineural hearing loss can usually not be restored and the damage is therefore permanent. This type of hearing loss is usually present in both ears but can also affect only one ear leaving the other ear’s hearing ability intact. The only treatment for this type of hearing loss is an assistive device such as hearing aid that can amplify the sound and restore hearing ability to some degree.
Mixed hearing loss
When someone has damage to both the outer and / or middle part of the ear as well as to the inner ear, it is called a mixed hearing loss. In some cases the conductive part of the hearing loss can still be treated medically but usually the person will still need to make use of an assistive listening device such as a hearing aid. A mixed hearing loss can be present in one or both ears depending on the cause of the hearing loss.
There is one more type of hearing loss that is worth mentioning, namely functional hearing loss.
Functional hearing loss
A functional hearing loss is when a person reports symptoms of a hearing loss in the absence of any physical or medical condition. There will be no conductive component to constitute a hearing loss and when tested the person will usually either have normal hearing ability or have inconsistent test results. A person showing a functional hearing loss can either be exaggerating an existing hearing loss or feigning a hearing loss altogether. Displaying a functional hearing loss can be conscious or unconscious and the possible reasons / motivation for this behavior must be investigated. It can be associated with a desire for compensation or financial gain for the hearing loss, psychological disorders, poor adaptation to a certain environment, frustration or personal problems. It is important that the Audiologist is aware of the possibility of a false or exaggerated hearing loss and evaluate the person accordingly in order to determine the true hearing thresholds.