Interference in the transmission of sound to the inner ear is called conductive hearing loss and is typically brought about by ear infections in infants and young children. Mildly threatening, medicine or surgery is often used to correct the condition.
Sensorineural hearing loss is a rare condition which is caused by problems in the auditory cortex of the brain and includes any malformation, dysfunction, or damage to the inner ear (cochlea). Cochlear hearing loss involves problems with either the inner hair cells or outer hair cells or both.
This is usually an inborn defect and causes are mostly unknown but can stem from hereditary or medical problems, and are almost always permanent. Hearing loss can range from mild, moderate, severe, or profound and at times progressive (hearing is gradually lost) or unilateral (loss only in one ear), hence, repeat audiologic testing should be done. Children with this type of hearing loss are fitted with hearing aids and will generally not benefit from medical or surgical remedies.
A combination of both conductive and sensorineural hearing loss is also possible and is called a mixed hearing loss.
Central hearing loss on the other hand, or "auditory processing disorder", occurs when the hearing parts of the brain shows difficulty in processing speech and other auditory information.
Causes of Hearing Loss
Being a common birth defect, 1 to 3 out of every 1,000 babies are often affected with a form of hearing loss and about half of the time, no cause can be found.
Some of the factors which greatly contribute to hearing loss in children would be:
- premature birth
- prolonged confinement in a neonatal intensive care unit
- a history of hearing loss in the family
- a transfusion due to high bilirubin
- medications which are known to cause hearing loss in infants
- ear infections such as meningitis or cytomegalovirus
- exposure to loud sounds