Types of Hearing Loss
There are four categories of hearing loss:
central, conductive, sensory-neural, and mixed.
Central Hearing Loss
This least common form of hearing impairment occurs as a result of a problem in the central auditory system. Although the outer, middle and inner ear parts deliver sound signals, they are not processed by the brain. Sound amplification does not address this type of dysfunction.
Conductive Hearing Loss
Conductive hearing loss results from malfunction of the outer and/or middle ear. Causes can be as simple as impacted earwax, or as serious as middle ear infection, eardrum perforation or dislocation of the middle ear bones.
Most of these symptoms can be medically or surgically treated. When treated in time, some conductive hearing losses may not require artificial amplification. Untreatable cases often result in the need for hearing instruments or other hearing assistive devices.
Sensory-neural Hearing Loss
By far the most common type of hearing impairment, sensory-neural loss is usually the result of cochlear hair cell damage. Sound may be conducted normally to the inner ear, but the damaged hair cells are unable to ‘trigger’ and therefore cannot send signals to the central auditory system. In most cases those that do ‘transmit’ are damaged and as a result send a distorted message to the brain.
Because the cochlea is tiny, and the hair cells are microscopic, there is no medical procedure and reversal of sensory-neural hearing loss treatment available. The loss can be aided with amplification, essentially allowing remaining hair cells to respond to the best of their abilities.
Common causes of sensory-neural hearing loss are:
- Prolonged exposure to excessive noise
- Hereditary predisposition
- Ototoxic medication
- Prenatal or congenital factors
Hearing and Age
Age is the most prevalent cause of hearing loss and impairment. Age induced hearing loss, known as presbycusis, occurs as part of the body’s natural wear and tear over time.
Mixed Hearing Loss
A condition in which both the conductive and sensory-neural hearing loss is present. Both the middle and inner ear are affected.