Types of Hearing Loss
Hearing loss can be present at birth or occur later in life, can last a short time or a lifetime, can be partial or total, slight to profound in severity and can be present in one ear (unilateral) or both ears (bilateral).
As you read about the different types of hearing loss, please visit AboutKidsHealth-Ear to facilitate your understanding.
Conductive Hearing Loss
A conductive hearing loss exists when there is an abnormality in the middle or outer ear but the inner ear (cochlea) 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 or rupture of the eardrum
- Small or absent ear canals or pinnas
- Abnormalities of the bones in the middle ear
Sensorineural Hearing Loss
In this type of loss, the problem lies in the inner ear (cochlea) or in the transmission of impulses along the auditory (hearing) 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 the 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 hearing aids.
There is usually no medical or surgical treatment for this type of hearing loss.
Potential causes include:
- Anatomical abnormalities of the cochlea
- Noise exposure
- Certain drugs that are toxic to the ear
- Head injuries
- Prolonged high fevers
- Meningitis, mumps, and measles
- Congenital Cytomegalovirus (CMV)
In many cases, especially when the child is born with the hearing loss, the cause remains unknown.
Mixed Hearing Loss
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.
Auditory Neuropathy Spectrum Disorder (ANSD)
ANSD is a hearing disorder in which the hearing organ located in the inner ear (cochlea) seems to receive sounds normally.
However, signals leaving the cochlea may be disorganized or the hearing itself may not process sound normally.
For more information see Auditory Neuropathy Spectrum Disorder.
Central, Corticol or Audiotry Processing Hearing Loss
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 Hearing Loss
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 unilateral hearing loss typically respond to normal conversation and environmental sounds and demonstrate normal or near normal speech and language development. Before Newborn Hearing Screens, the average age at which a child with a unilateral hearing loss was identified was older than that of a child with a bilateral hearing loss. Thus, many of these children were not identified until they were in school.
For more information see Unilateral Hearing Loss