Types of Hearing Loss

Hearing loss is categorized by what part of the auditory system is affected. The four basic types of hearing loss are conductive hearing loss, Sensorineural hearing loss, mixed hearing loss and central auditory processing disorders.

Conductive Hearing Loss:
Conductive hearing loss occurs when sound does not move efficiently through the outer or middle ear systems. The presence of a foreign bodies, impacted Cerumen (ear wax) and fluid in the middle ear from colds, allergies or ear infections can all cause conductive hearing loss. In addition, disorders or malformation of the pinna, ear canal or ossicles (tiny bones in the middle ear) can cause this type of loss. Conductive hearing loss can often be corrected with medicine or surgery.

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Sensorineural Hearing Loss:
Sensorineural hearing loss results from damage to the cochlea (inner ear) or to the auditory nerve that runs from the cochlea to the brain. Certain diseases, injuries, ototoxic drugs and genetic syndromes can cause Sensorineural hear loss. It can also occur as a result of noise exposure, viruses, head trauma, aging and tumors. Usually, Sensorineural hearing loss is permanent and cannot be medically or surgically corrected.

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Mixed Hearing Loss:
Mixed hearing loss occurs when there is damage to both the outer/middle ear systems and the inner ear or auditory nerve resulting in a combination of Sensorineural and conductive hearing loss.

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Congenital Hearing Loss:
Congenital hearing loss refers to hearing loss that is present at birth. Hearing loss can be conductive or Sensorineural in nature and range from mild to profound in severity. Congenital hearing loss may be due to genetic abnormalities or from other factors such as infections, illnesses or conditions occurring at the time of birth or shortly thereafter. Some examples of genetic syndromes that are associated with hearing loss are Down syndrome, Usher syndrome, Treacher-Collins syndrome, Fetal alcohol syndrome, Crouzon syndrome and Alport syndrome. Non-hereditary causes of congenital hearing loss include rubella, cytomegalovirus, herpes simplex, RH factor incompatibility, prematurity, maternal diabetes, toxemia during pregnancy, lack of oxygen at birth, syphilis and malformation of the ear.

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Acquired Hearing Loss:
Acquired hearing loss appears after birth or at a later time in life, as a result of a disease, condition or an injury. Examples of conditions that can cause acquired hearing loss in children include ear infections, ototoxic drugs, meningitis, measles, encephalitis, chicken pox, influenza; mumps head injury and noise exposure.

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Central Auditory Processing Disorders:
Central auditory processing disorders (CAPD) occur when the parts of the brain that interpret sound are affected by injury, disease, tumor or other unknown causes. Central auditory processing disorders may result in a diminished ability to localize sound, discriminate and recognize auditory patterns, utilize temporal aspects of sound, or deal with degraded or competing acoustic signals.