Types of Hearing Loss
A conductive hearing loss exists when there is an abnormality in the middle or outer ear but the inner ear functions normally. This causes sound to be attenuated before it reaches the inner ear. This type of loss often can be treated with either medication or surgery. The most common conductive hearing loss seen in children is caused by otitis media (ear infections causing accumulation of fluid in the middle ear).
Other causes include:
--extreme wax buildup
--holes in the eardrum
--small or absent ear canals or pinnas
--abnormalities of the bones in the middle ear
In this type of loss, the problem lies in the inner ear or in the transmission of impulses along the auditory nerve.
Within the cochlea, the site of damage is usually the sensory hair cells. As a result of the hearing loss, not only does the individual notice decreased sensitivity to sound, but there is often a decrease in the clarity of sound as well. Sound may reach the inner ear, but because of damage to the cochlea or auditory nerve, it is not received clearly by the brain, even if it is made sufficiently loud through the use of amplification.
There is usually no medical treatment for this type of hearing loss.
Potential causes include:
--anatomical abnormalities of the cochlea
--prolonged high fevers
--meningitis, mumps, and measles
In many cases, especially when the child is born with the hearing loss, the cause remains unknown.
A mixed hearing loss is a combination of both a conductive and a sensorineural hearing loss. Usually the conductive component can be treated with medication or surgery, but no treatment is available for the sensorineural component.
Central or Cortical
This type of hearing loss refers to the inability of the brain to interpret sound information even though peripheral hearing sensitivity is essentially normal. Varying degrees of auditory comprehension result.
Unilateral or Bilateral
Hearing loss is also referred to as either unilateral or bilateral, depending on whether one or both ears are affected.
In a unilateral hearing loss, there is a hearing loss in one ear and normal hearing in the other. Unlike children with bilateral hearing loss, children with a unilateral hearing loss typically respond to normal conversation and environmental sounds and demonstrate normal speech and language development. Because of this, the average age at which a child with a unilateral hearing loss is identified is generally later than that of a child with a bilateral hearing loss. Thus, many of these children are not identified until they are in school.
Individuals with unilateral hearing loss find sound localization extremely difficult. That is, they have problems determining where a sound originates from. This is an important consideration in terms of classroom management of this child. Many of the educational implications for children with bilateral hearing loss are similar for a child with a unilateral hearing loss as well.
Factors such as type, degree, duration and etiology of the hearing loss, and even the child's intelligence may affect how the child responds to his or her hearing difficulty.
See a picture of the ear
See the classifications and impacts of hearing loss