There are two types of hearing impairment. When there is some difficulty in the external or middle ear, a conductive hearing impairment occurs. When the trouble lies in the inner ear, a sensorineural or nerve hearing impairment is the result. Difficulty in both the middle and inner ear results in a mixed impairment. A complete otologic examination by an otologist and an audiologic evaluation by an audiologist are necessary to determine what type of hearing impairment is present, its possible causes, and its treatment.
A conductive impairment may result from a blockage of the external ear canal, a perforation (hole) in the tympanic membrane (eardrum), a middle ear infection, fluid accumulation due to blockage of the Eustachian tube, or a congenital defect or disease of any of the three middle ear bones.
“Sensorineural impairment” is the term used to describe hearing losses which result from disturbances or defects in the inner ear and/or hearing nerve transmission. These impairments may be congenital (present at birth), hereditary (genetic), or developmental, or a combination of these. Fortunately, only one in 100 children with a sensorineural impairment will show a progression of the impairment over time.
German measles or certain other viruses contracted by a mother during the first three months of pregnancy may interfere with inner year development in the fetus. The viruses of measles and mumps may infrequently cause a sensorineural impairment after birth.
Problems at birth
Jaundice (turning yellow) occurring at or shortly after birth is capable of damaging the inner ear. This is most often due to RH incompatibility between the mother’s and the child’s blood. Fortunately, this is preventable and uncommon today. Difficulties in childbirth that result in oxygen deprivation to the infant may also damage the inner ear. The earlier the difficulty is diagnosed, the better the chance to intervene to improve hearing and/or language development.
Hereditary sensorineural hearing impairment may be present at birth or may develop later in life. Even though there may be no hearing impairment in the parents, careful questioning may reveal some more distant relative with a similar problem.
Meningitis occasionally results in sensorineural hearing loss, which may be mild to profound. Ear infections rarely lead to sensorineural hearing loss.
How Does This Hearing Loss Affect My Child?
Impaired hearing can have a profound effect on the social development of young children. An inability to communicate may produce behavioral problems in hearing impaired children, and extreme frustration in both children and parents. Both the amount and type of hearing loss are critically important factors in a child’s speech development. However, speech development is also influenced by the age of diagnosis and institution of treatment, adequacy of amplification, and help provided by parents and educators.
Mild hearing loss
The child with mild hearing loss usually has normal speech, but will have trouble in the school setting because it will be difficult to hear speech from more than 12 feet away or when there is background noise. This is because much of the meaning in English is contained in the voiceless consonants, which are high pitched and soft. They are s, sh, t, p, k, f, ch, and th. A child with a mild loss in both ears will need some amplification in each ear to hear clearly at school, in groups, or at a distance.
Some children with a mild loss are not suspected of poor hearing until they reach first grade. They are often thought to be “slow,” because they cannot understand when the teacher speaks from a distance and, therefore, respond erratically. When these children receive hearing aids, they usually find that school is easier and their school performance improves.
Children with moderate hearing loss can clearly hear speech only when the speaker is very close – less than two feet away. They need hearing aids to hear the softest sounds and to acquire understandable speech. If they receive hearing aids before four years of age, they usually progress rapidly in learning speech. They can attend regular schools, but may need some special help.
Children with a severe hearing loss do not perceive speech, no matter how close they are to the speaker. They will not learn to talk intelligently without hearing aids and special help.
Severely impaired children who receive hearing aids early in life have a far better chance of acquiring useful speech than children who remain unaided longer. This is not to say that a child with a severe loss who gets hearing aids at age three will never learn to speak, but it does mean the task will be harder. Many children who do not receive hearing aids until after age six may never develop clear speech or the ability to easily understand spoken words.
All children with severe hearing losses require special help because they receive only a portion of the clues usually available in speech sounds. With hearing aids, they can detect vowel sounds, pitch, some consonants, and stress clues from speech. With visual input from lip reading, they can learn to detect about 25 percent of the consonant sounds. By using lip reading and listening together, they may receive about half of the clues that normal hearing people use to understand speech.
Children with a profound hearing loss receive even less auditory information. The younger a child is when fitted with hearing aids or a cochlear implant, the greater the likelihood he/she will develop improved speech. Children with a profound loss often depend greatly on their vision to perceive speech.
Fortunately, the child with a conductive hearing impairment will always be able to hear, either through ear surgery or by the use of properly fitted hearing aids.
There is no known medical or surgical treatment that will restore hearing in sensorineural hearing impairment. Treatment consists of rehabilitation through the use of hearing aids and special training. Children with profound sensorineural hearing loss can be treated with a cochlear implant.
Hearing impairment in one ear
A hearing impairment that is confined to one ear deprives a person of the ability to distinguish the direction of sound. He or she will also have difficulty hearing in a noisy background. These are usually minor problems to a young child; however, the child should be carefully monitored. Sometimes speech and language delays may develop. Once the child is of school age, special considerations may be needed