When there is damage to any part of the path that sound takes through the hearing system, hearing ability may be compromised. A person is hearing impaired if there is a hearing loss less than 90 decibels (dB). In case of hearing loss of 90 dB or more, a person is deaf. Hearing impairment is divided into several categories: (1) conductive hearing loss–here, the problem is located in the outer ear or the middle ear.
This is normally caused by cerumen (earwax), middle ear diseases or otosclerosis (the eardrum and the ossicles have increased mobility) (2) sensorineural hearing loss–In this kind of hearing loss, the inner ear of the hearing nerve is affected. The loss is normally permanent and more in the higher frequencies than the lower frequencies. This type of hearing impairment is normally caused by congenital or inherited reasons, noise trauma, aging, trauma (head injury) or a tumor compressing the hearing nerve. (3)
Mixed–some combination of sensorineural and conductive hearing loss The most common cause associated with either of the categories are as follows: Family history of hereditary childhood sensorineural hearing loss In utero infection, such as cytomegalovirus, rubella, syphilis, herpes and toxoplasmosis Craniofacial anomalities, including those with abnormalities of the pinna and ear canal Birth weight less than 1,500 grams Hyperbilirubinemia at a serum level requiring exchange transfusion Bacterial meningitis Mechanical ventilation lasting 5 days or longer Stigmata or other findings associated with a syndrome known to include a sensorineural and/or conductive hearing loss Head trauma associated with loss of consciousness or skull fracture Neurodegenerative disorders Perforation of the ear drum
Therapy for conductive hearing loss often involves treatment with medication or surgery. A person suffering from sensorineural hearing loss is best helped with the use of a hearing aid. In the case of a tumor, the impairment can normally only be helped if the tumor is removed in an early stage. There is no treatment which can restore the inner ear. Medical or surgical treatment of hearing loss is almost exclusively confined to abnormalities or diseases of the middle and outer ear.
Some malformations of the outer ear and middle ear can be partly or wholly corrected by surgery but there are risks involved with the surgical procedures. These risks include paralysis of the face, further loss of hearing in the operated ear or postoperative infections. One in every 10 Americans is hearing impaired. This translates into 28 million cases.
Although many of these cases arise from loud music, loud sounds, antibiotics and accidents, genetics is frequently an undiagnosed cause. Researchers are now saying that up to 60% of hearing loss is genetic in origin. Many of the patients with family history of hearing loss are never examined for possible hereditary causes of the hearing impairment. Each year in the United States, 4,000 children are born with a hearing loss and another 37,000 have milder degrees of loss that have a significant impact on their speech, language and educational development. Certain factors can influence the impact of a hearing loss on a child's development.
A child born with a hearing loss has a greater risk of delayed speech and language development than a child that acquires the hearing impairment after speech and language are developed. The degree of the impairment also has a major impact. If a child's hearing loss is not identified at birth, it generally goes undetected until the child reaches 2 ½ years of age. This causes severe speech and language delays. One would think that a hearing screening would be routine at birth, but it is not. Unlike hearing tests for older children, which require the child to respond to respond to a sound by raising a hand, hearing tests for infants measure vibrations produced by the cochlea.
The infant tests are painless. If the vibrations are weak, further computer-aided testing can measure the baby's brain activit in response to noise, confirming the diagnosis of a hearing impairment. The prognosis for the intellectual, emotional, language and speech development of the hearing impaired child is improved when the diagnosis is made early and intervention is begun before the age of 6 months. Neonatal screening gives hearing impaired children the very best prognosis of optimal care and development. Children who are hearing impaired are a very diverse group.
A wide range of educational choices are needed to meet their teaching a learning needs. Some may learn best in a special setting for students who are hearing impaired, while others are best served in integrated or mainstream educational environments. One should also realize that the educational needs of the hearing impaired may change as the child develops. I have concentrated most of my presentation on hearing impaired children. Hearing impairment affects all ages, races, creeds and sexes. It is a major health problem throughout the world.
References
- Wade, Will. (2000) Hearing Trouble. http://www.my.webmd.com/content/Article/13/1739_50509.htm?printing=true
- Hearing Loss. http://widex-master.dynamicweb.dk/Default.asp?ID=69
- Hearing Impairment. http://www.ridbc.org.au/information/hearing/hearing_education.html
- Hearing Impairment and Deafness. http://jmk.su.se/global99/access/hearing/inthetxt.html
- Hearing Loss: Genetic Defects. http://hearform.com/articles/genetic_defects.htm
