What Is Hearing Impairment?

What Is Hearing Impairment?

Hearing impairment occurs when there's a problem with or damage to one or more parts of the ear.

Conductive hearing loss results from a problem with the outer or middle ear, including the ear canal, eardrum, or ossicles. A blockage or other structural problem interferes with how sound gets conducted through the ear, making sound levels seem lower. In many cases, conductive hearing loss can be corrected with medications or surgery.

Sensorineural (pronounced: sen-so-ree-nyour-ul) hearing loss results from damage to the inner ear (cochlea) or the auditory nerve. The most common type is caused by the outer hair cells not functioning correctly. The person has trouble hearing clearly, understanding speech, and interpreting various sounds. This type of hearing loss is permanent. It may be treated with hearing aids.

In most severe cases, both outer and inner hair cells aren't working correctly. This is also a type of permanent hearing loss and can be treated with a cochlear implant. In some other cases, the outer hair cells work correctly, but the inner hair cells or the nerve are damaged. This type of hearing loss is called auditory neuropathy spectrum disorder. The transmission of sound from the inner ear to the brain is then disorganized.

Children with auditory neuropathy spectrum disorder can develop strong language and communication skills with the help of medical devices, therapy, and visual communication techniques.

Mixed hearing loss happens when someone has both conductive and sensorineural hearing problems.

Central hearing loss happens when the cochlea is working properly, but other parts of the brain are not. This is a less frequent type of hearing loss and is more difficult to treat.

Auditory processing disorders (APD). This is not exactly a type of hearing loss because someone with APD can usually hear well in a quiet environment. But most people with APD have difficulty hearing in a noisy environment, which is the usual environment we live in. In most cases, APD can be treated with proper therapy.

The degree of hearing impairment can vary widely from person to person. Some people have partial hearing loss, meaning that the ear can pick up some sounds; others have complete hearing loss, meaning that the ear cannot hear at all (people with complete hearing loss are considered deaf). In some types of hearing loss, a person can have much more trouble when there is background noise. One or both ears may be affected, and the impairment may be worse in one ear than in the other.

The timing of the hearing loss can vary, too. Congenital hearing loss is present at birth. Acquired hearing loss happens later in life — during childhood, the teen years, or in adulthood — and it can be sudden or progressive (happening slowly over time).

According to the National Institute on Deafness and Other Communication Disorders, about 28 million Americans are deaf or hearing impaired. That's about 1 out of every 10 people. Another 30 million are exposed to hazardous noise levels on a regular basis. Hearing loss is also the most common birth anomaly

r genes"? They were probably talking about a physical characteristic, personality trait, or talent that you share with other members of your family.

We know that genes play an important role in shaping how we look and act and even whether we get sick. Now scientists are trying to use that knowledge in exciting new ways, such as treating health problems.

What Is a Gene?

To understand how genes work, let's review some biology basics. Most living organisms are made up of cells that contain a substance called deoxyribonucleic (pronounced: dee-AHK-see-rye-bow-noo-klee-ik) acid (DNA).

DNA contains four chemicals (adenine, thymine, cytosine, and guanine — called A, T, C, and G for short) that are strung in patterns on extremely thin, coiled strands in the cell. How thin? Cells are tiny — invisible to the naked eye — and each cell in your body contains about 6 feet of DNA thread, for a total of about 3 billion miles of DNA inside you!

So where do genes come in? Genes are made of DNA, and different patterns of A, T, G, and C code for the instructions for making things your body needs to function (like the enzymes to digest food or the pigment that gives your eyes their color). As your cells duplicate, they pass this genetic information to the new cells.

DNA is wrapped together to form structures called chromosomes. Most cells in the human body have 23 pairs of chromosomes, making a total of 46. Individual sperm and egg cells, however, have just 23 unpaired chromosomes. You received half of your chromosomes from your mother's egg and the other half from your father's sperm cell. A male child receives an X chromosome from his mother and a Y chromosome from his father; females get an X chromosome from each parent.

Genes are sections or segments of DNA that are carried on the chromosomes and determine specific human characteristics, such as height or hair color. Because you have a pair of each chromosome, you have two copies of every gene (except for some of the genes on the X and Y chromosomes in boys, because boys have only one of each).

Some characteristics come from a single gene, whereas others come from gene combinations. Because every person has about 25,000 different genes, there is an almost endless number of possible combinations

how Is It Treated?

Treatment for hearing loss varies depending upon the cause of the hearing impairment

Treatment may involve removing wax or dirt from the ear or treating an underlying infection. If there is damage or a structural problem with the eardrum or ossicles, surgery may help to repair it. If the problem is with the cochlea or hearing nerve, a hearing aid or cochlear implant may be recommended.

Hearing aids come in various forms that fit inside or behind the ear and make sounds louder. They are adjusted by the audiologist so that the sound coming in is amplified enough to allow the person with a hearing impairment to hear it clearly.

Sometimes, the hearing loss is so severe that the most powerful hearing aids can't amplify the sound enough. In those cases, a cochlear implant may be recommended.

Cochlear implants are surgically implanted devices that bypass the damaged inner ear and send signals directly to the auditory nerve. A small microphone behind the ear picks up sound waves and sends them to a receiver that has been placed under the scalp. This receiver then transmits impulses directly to the auditory nerve. These signals are perceived as sound and allow the person to hear.

Depending upon whether someone is born without hearing (congenital deafness) or loses hearing later in life (after learning to hear and speak, which is known as post-lingual deafness), medical professionals will determine how much therapy the person needs to learn to use an implant effectively. Many people with implants learn to hear sounds effectively and even use the telephone.

More than 200,000 people around the world have received cochlear implants and about one third of them are children.

Some patients with hearing loss and their families may decide not to restore hearing. This is particularly true of children whose parents are hearing impaired and want their children to be able to function in the deaf community. The language of the deaf community is American Sign Language (ASL). ASL is a system of gestures many deaf and hearing-impaired people use to communicate

Description:

A hearing impairment is a hearing loss that prevents a person from totally receiving sounds through the ear. If the loss is mild, the person has difficulty hearing faint or distant speech. A person with this degree of hearing impairment may use a hearing aid to amplify sounds. If the hearing loss is severe, the person may not be able to distinguish any sounds. There are four types of hearing loss:

Conductive: caused by diseases or obstructions in the outer or middle ear that usually affect all frequencies of hearing. A hearing aid generally helps a person with a conductive hearing loss.

Sensorineural: results from damage to the inner ear. This loss can range from mild to profound and often affects certain frequencies more than others. Sounds are often distorted, even with a hearing aid.

Mixed: occurs in both the inner and outer or middle ear.

Central: results from damage to the central nervous system.

People with hearing impairment can communicate using numerous methods of communication, such as:

American Sign Language (ASL): This is the primary language of people who are deaf. It consists of a combination of hand movements and positions to express thoughts and phrases.

Finger spelling: This is a manual form of communication in which the hand and fingers spell out letters of the alphabet to form words.

Lipreading: This is a difficult skill used only by about 10% of people with hearing impairments. Therefore, don't assume that a deaf person to whom you are speaking can lip read. Even if a person cannot lip read, however, being allowed to see the speaker's mouth provides helpful visual cues.

Written communication ("Pad and Pencil"): This is a fairly simple way to communicate with a person who is deaf. Remember, however, that sign language is the primary language for most persons who are deaf; English is a second language, so keep your words simple.

Oral communication

(From: "Those of Us DisLabeled: A Guide to Awareness and Understanding", University of Kentucky Human Development Institute, Cooperative Extension Service)

Adaptations/Accommodations:

Smile and maintain eye contact during the time you are talking to a person who is hearing impaired. The person always needs to be able to see your lips if he has learned to read lips. If a sign language interpreter is present, talk directly to the person who is deaf, not the interpreter.

If at all feasible, use complete sentences, especially when communicating with children. Good language development is dependent upon correct use of verbs, adjectives, adverbs, nouns, etc. Restricting communication to a single word or short phrase deprives this population of opportunities to master the English language, thus limiting their academic development.

Speak slowly and clearly, but do not exaggerate. Be expressive, but not overly so.

If a word is not understood, try another word. Demonstrate if possible.

Use sign language only if you're qualified. Otherwise, incorrect information may be conveyed.

Do not shout. Hearing aids make sounds louder, but they do not clarify the person's reception or understanding of the sound. The presence of a hearing aid does not mean that the person can hear normally.

If all else fails, use a pad and pencil to communicate. Since this often isolates the person with a hearing impairment from the group, try to use writing only if oral speech, lip reading, sign language, gestures, and finger spelling have failed.

During group gatherings, seat the person with a hearing impairment so s/he can see others in the group. Try a semi-circle arrangement. If possible, arrange to have an interpreter or note-taker. Use visual aids whenever possible.

Watch the person who is deaf or hearing impaired carefully for facial expressions and body language that will help you determine the success of your communication.

If you have trouble understanding the speech of a person who is deaf, don't hesitate to ask him to repeat what he said. Your willingness and desire to communicate is what is most important, not the ease with which you understand

.Visual Impairment

Definition

Total blindness is the inability to tell light from dark, or the total inability to see. Visual impairment or low vision is a severe reduction in vision that cannot be corrected with standard glasses or contact lenses and reduces a person's ability to function at certain or all tasks. Legal blindness (which is actually a severe visual impairment) refers to a best-corrected central vision of 20/200 or worse in the better eye or a visual acuity of better than 20/200 but with a visual field no greater than 20° (e.g., side vision that is so reduced that it appears as if the person is looking through a tunnel).

Description

Vision is normally measured using a Snellen chart. A Snellen chart has letters of different sizes that are read, one eye at a time, from a distance of 20 ft. People with normal vision are able to read the 20 ft line at 20 ft-20/20 vision—or the 40 ft line at 40 ft, the 100 ft line at 100 ft, and so forth. If at 20 ft the smallest readable letter is larger, vision is designated as the distance from the chart over the size of the smallest letter that can be read.

Eye care professionals measure vision in many ways. Clarity (sharpness) of vision indicates how well a person's central visual status is. The diopter is the unit of measure for refractive errors such as nearsightedness, farsightedness, and astigmatism and indicates the strength of corrective lenses needed. People do not just see straight ahead; the entire area of vision is called the visual field. Some people have good vision (e.g., see clearly) but have areas of reduced or no vision (blind spots) in parts of their visual field. Others have good vision in the center but poor vision around the edges (peripheral visual field). People with very poor vision may be able only to count fingers at a given distance from their eyes. This distance becomes the measure of their ability to see.

The World Health Organization (WHO) defines impaired vision in five categories:

Low vision 1 is a best corrected visual acuity of 20/70.

Low vision 2 starts at 20/200.

Blindness 3 is below 20/400.

Blindness 4 is worse than 5/300

Blindness 5 is no light perception at all.

A visual field between 5° and 10° (compared with a normal visual field of about 120°) goes into category 3; less than 5° into category 4, even if the tiny spot of central vision is perfect.

Color blindness is the reduced ability to perceive certain colors, usually red and green. It is a hereditary defect and affects very few tasks. Contrast sensitivity describes the ability to distinguish one object from another. A person with reduced contrast sensitivity may have problems seeing things in the fog because of the decrease in contrast between the object and the fog.

According to the WHO there are over forty million people worldwide whose vision is category 3 or worse, 80% of whom live in developing countries. Half of the blind population in the United States is over 65 years of age.

Causes and symptoms

The leading causes of blindness include:

macular degeneration

glaucoma

cataracts

diabetes mellitus

Other possible causes include infections, injury, or nutrition.

Infections

Most infectious eye diseases have been eliminated in the industrialized nations by sanitation, medication, and public health measures. Viral infections are the main exception to this statement. Some infections that may lead to visual impairment include:

Herpes simplex keratitis. A viral infection of the cornea. Repeated occurrences may lead to corneal scarring.

Trachoma. This disease is responsible for six to nine million cases of blindness around the world, of the third of a billion who have the disease. Trachoma is caused by an incomplete bacterium, Chlamydia trachomatis, that is easily treated with standard antibiotics. It is transmitted directly from eye to eye, mostly by flies. The chlamydia gradually destroy the cornea.

Leprosy (Hansen's disease). This is another bacterial disease that has a high affinity for the eyes. It, too, can be effectively treated with medicines.

River blindness. Much of the tropics of the Eastern Hemisphere are infested with Onchocerca volvulus, a worm that causes "river blindness." This worm is transmitted by fly bites and can be treated with a drug called ivermectin. Nevertheless, twenty-eight million people have the disease, and 40% of them are blind from it.

Other causes

Exposure of a pregnant woman to certain diseases (e.g., rubella or toxoplasmosis) can cause congenital eye problems. Injuries to the eyes can result in blindness. Very little blindness is due to disease in the brain or the optic nerves. Multiple sclerosis and similar nervous system diseases, brain tumors, diseases of the eye sockets, and head injuries are rare causes of blindness.

Nutrition

Vitamin A deficiency is a widespread cause of corneal degeneration in children in developing nations. As many as five million children develop xerophthalmia from this deficiency each year. Five percent end up blind.

Diagnosis

A low vision exam is slightly different from a general exam. While a case history, visual status, and eye health evaluation are common to both exams, some things do differ. Eye charts other than a Snellen eye chart will be used. Testing distance will vary. A trial frame worn by the patient is usually used instead of the instrument containing the lenses the patient sits behind (phoropter). Because the low vision exam is slightly more goal oriented than a general exam, for example, what specifically is the patient having trouble with (reading, seeing street signs, etc.) different optical and nonoptical aids will generally be tried. Eye health is the last thing to be checked so that the lights necessary to examine the eyes will not interfere with the rest of the testing.