HEARING LOST IN WAR !!!

SAN DIEGO - Large numbers of soldiers and Marines caught in roadside bombings and firefights in Iraq and Afghanistan are coming home with permanent hearing loss and ringing in their ears, prompting the military to redouble its efforts to protect the troops from noise.

Hearing damage is the No. 1 disability in the war on terror, according to the Department of Veterans Affairs, and some experts say the true toll could take decades to become clear. Nearly 70,000 of the more than 1.3 million troops who have served in the two war zones are collecting disability for tinnitus, a potentially debilitating ringing in the ears, and more than 58,000 are on disability for hearing loss, the VA said.

"The numbers are staggering," said Theresa Schulz, a former audiologist with the Air Force, past president of the National Hearing Conservation Association and author of a 2004 report titled "Troops Return With Alarming Rates of Hearing Loss."

U.S. Army Sgt. Ryan Kahlor listens for sounds as his hearing is tested at Balboa Navy Medical Center in San Diego, Feb. 6, 2008. Kahlor's hearing was damaged by exposure to multiple IAD blasts in Iraq.

Hearing aid

Behind the ear aid

In the ear aid

For the song, see Flood (They Might Be Giants album).

A hearing aid is an electroacoustic body-worn apparatus which typically fits in or behind the wearer's ear, and is designed to amplify and modulate sounds for the wearer. Earlier devices, known as an "ear trumpet" or "ear horn", were passive funnel-like amplification cones designed to gather sound energy and direct it into the ear canal. Similar devices include the bone anchored hearing aid, and cochlear implant.

Types of hearing aids

There are many types of hearing aids (also known as hearing instruments), which vary in size, power and circuitry. Among the different sizes and models are:

NIH illustration of different hearing aid types.

Body worn aids

This was the first type of hearing aid invented by Harvey Fletcher while working at Bell Laboratories. Thanks to developments in technology they are now rarely used. These aids consist of a case containing the components of amplification and an ear mold connected to the case by a cord. The case is about the size of a pack of playing cards and is worn in the pocket or on a belt. Because of their large size, body worn aids are capable of large amounts of amplification and were once used for profound hearing losses. Today, body aids have largely been replaced by Behind-The-Ear (BTE) instruments.

Behind the ear aids (BTE)

BTE aids have a small plastic case that fits behind the pinna (ear) and provides sound to the ear via air conduction of sound through a small length of tubing, or electrically with a wire and miniature speaker placed in the ear canal. The delivery of sound to the ear is usually through an earmold that is custom made, or other pliable fixture that contours to the individuals ear. BTEs can be used for mild to profound hearing losses and are especially useful for children because of their durability and ability to connect to assistive listening devices such as classroom FM systems. Their colors range from very inconspicuous skin tones to bright colors and optional decorations. Recent innovations in BTEs include miniature "invisible" BTEs with thin hair-like sound tubes (see open-fit devices below). These are often less visible than In-The-Ear aids (ITEs) and some keep the ear canal more open so listeners may still utilise their residual natural hearing (most helpful for those with normal hearing in the lower frequencies). Ideal for high frequency losses, these miniature versions are generally used for mild to moderate hearing loss.

In the ear aids (ITE)

These devices fit in the outer ear bowl (called the concha); they are sometimes visible when standing face to face with someone. ITE hearing aids are custom made to fit each individual's ear. They can be used in mild to some severe hearing losses. Feedback, a squealing/whistling caused by sound of leaking air and being amplified again, may be a problem for severe hearing losses. Some modern circuits are able to provide feedback regulation or cancellation to assist with this. Traditionally, ITEs have not been recommended for young children because their fit could not be as easily modified as the earmold for a BTE, and thus the aid had to be replaced frequently as the child grew. However, there are new ITEs made from a silicone type material that mitigates the need for costly replacements.

Receiver In the ear aids (RITE)

At a first glance, these devices are similar to the BTE aid. There is however one crucial difference: The speaker ('receiver') of the hearing aid is placed inside the ear canal of the user and thin electrical wires replace the acoustic tube of the BTE aid. There are some advantages with this approach: Firstly, the sound of the hearing aid is arguably smoother than that of a traditional BTE hearing aid. With a traditional BTE hearing aid, the amplified signal is emitted by the speaker (receiver) which is located within the body of the hearing aid (behind the ear). The amplified signal is then directed to the ear canal through an acoustic tube, which creates a peaky frequency response. With a RITE hearing aid, the speaker (receiver) is right in the ear canal and the amplified output of the hearing aid does not need to be pushed through an acoustic tube to get there, and is therefore free of this distortion. Secondly, RITE hearing aids can typically be made with a very small part behind-the-ear and the wire connecting the hearing aid and the speaker (receiver) is extremely inconspicuous. For the majority of people this is one of the most cosmetically acceptable hearing device types. Thirdly, RITE devices are suited to "open fit" technology (see below) so they can be fitted without plugging up the ear, offering relief from occlusion.

In the canal (ITC), mini canal (MIC) and completely in the canal aids (CIC)

ITC aids are smaller, filling only the bottom half of the external ear. You usually cannot see very much of this hearing aid when you are face to face with someone. MIC and CIC aids are often not visible unless you look directly into the wearer's ear. These aids are intended for mild to moderately-severe losses. CICs are usually not recommended for people with good low frequency hearing, as the occlusion effect is much more perceivable.

Open-fit devices

"Open-fit" or "Over-the-Ear" OTE hearing aids are small behind-the-ear type devices. This type is characterized by a small plastic case behind the ear, and a very fine clear tube running into the ear canal. Inside the ear canal, a small soft silicone dome or a molded, highly vented acrylic tip holds the tube in place. This design is intended to reduce the occlusion effect. Conversely, because of the increased possibility of feedback, they are limited to moderate high frequency losses.

Bone Anchored Hearing Aids (BAHA)

The BAHA is a auditory prosthetic which can be surgically implanted. The BAHA uses the skull as a pathway for sound to travel to the inner ear. For people with conductive losses, the BAHA, bypasses the external auditory canal and middle ear, stimulating the functioning cochlea. For people with unilateral hearing loss, the BAHA uses the skull to conduct the sound from the deaf side to the side with the functioning cochlea.

Individuals under the age of 5 typically wear the BAHA device on a headband. Over age 5, a titanium "post" can be surgically embedded into the skull with a small abutment exposed outside the skin. The BAHA sound processor sits on this abutment and transmits sound vibrations to the external abutment of the titanium implant. The implant vibrates the skull and inner ear, which stimulate the nerve fibers of the inner ear, allowing hearing.

Eyeglass aids

During the late 1950s through 1970s, before in-the-ear aids became common (and in an era when thick-rimmed eyeglasses were popular), people who wore both glasses and hearing aids frequently chose a type of hearing aid that was built into the temple pieces of the spectacles. However, the combination of glasses and hearing aids was inflexible: the range of frame styles was limited, and the user had to wear both hearing aids and glasses at once or wear neither. Today, people who use both glasses and hearing aids can use in-the-ear types, or rest a BTE neatly alongside the arm of the glasses. There still are some specialized situations where hearing aids built into the frame of eyeglasses can be useful, such as when a person has hearing loss mainly in one ear: sound from a microphone on the "bad" side can be sent through the frame to the side with better hearing.

• This can also be achieved by using CROS or bi-CROS style hearing aids, which are now wireless in sending sound from the "bad" or "worse" side to the better side.

Recently, a new type of eyeglass aid was introduced. These 'hearing glasses' feature directional sensitivity: four microphones on each side of the frame effectively work as two directional microphones, which are able to discern between sound coming from the front and sound coming from the sides or back of the user ^[6]. This improves the Signal-to-noise ratio by allowing for amplification of the sound coming from the front, the direction in which the user is looking, and active noise control for sounds coming from the sides or back. Only very recently has the technology required become small enough, in size, to be put in the frame of the glasses. As a recent addition to the market, the geographical market for this particular hearing aid is currently limited to a few European countries.

Noise-induced hearing loss

Noise-induced hearing loss (NIHL) is an increasingly prevalent disorder that results from exposure to high-intensity sound, especially over a long period of time.

Description

NIHL is a preventable hearing disorder that affects people of all ages and demographics. According to a position statement released by the American Academy of Audiology in 2003;

"The average, otherwise healthy, person will have essentially normal hearing at least up to age 60 if his or her ears are not exposed to high noise levels".

Unfortunately, around 30 million adults in the United States are exposed to hazardous sound levels in the workplace. Among these 30 million people, one in four will acquire a permanent hearing loss as result of their occupation (AAA, 2003). Even though NIHL primarily affects the adult working population, NIHL can be identified in the adolescent and young adult population as well. “The Hearing Alliance of America reports that 15 percent of college graduates have a level of hearing loss equal to or greater than their parents”. The incidence of NIHL in young adults is not surprising, due to the popularity of portable music devices (Walkmans and iPods), concerts, and nightclubs within this population. However, through education, audiological evaluations, hearing conservation programs in the workplace, and the proper use of ear protectors, NIHL is preventable.

Mechanism of Causes

NIHL occurs when too much sound intensity is transmitted into and through the auditory system. An acoustic signal from an energy source, such as a radio, enters into the external auditory canal, and is funneled through to the tympanic membrane. The tympanic membrane acts as an elastic diaphragm and drives the ossicular chain of the middle ear system into motion. Then the middle ear ossicles transfer mechanical energy to the cochlea by way of the stapes footplate hammering against the oval window of the cochlea. This hammering causes the fluid within the cochlea (perilymph and endolymph) to push against the stereocilia of the hair cells, which then transmit a signal to the central auditory system within the brain. When the ear is exposed to excessive sound levels or loud sounds over time, the force placed on the stereocilia of the hair cells becomes damaging, producing abnormalities of the cells.

“

Some of the abnormalities include metabolic exhaustion of the hair cells, structural changes and degeneration of structures within the hair cells, morphological changes of the cilia, ruptures of cell membranes, and complete degeneration and loss of hair cells, neural cells and supporting cells. (Gelfand, 2001, p. 202)

”

NIHL is therefore the consequence of overstimulation of the hair cells and supporting structures. Structural damage to hair cells (primarily the outer hair cells) will result in hearing loss that can be characterized by an attenuation and distortion of incoming auditory stimuli.

Types

There are two basic types of NIHL:

• NIHL caused by acoustic trauma and
• gradually developing NIHL.

Acoustic Trauma

NIHL caused by acoustic trauma refers to permanent cochlear damage from a one-time exposure to excessive sound pressure. This form of NIHL commonly results from exposure to high-intensity sounds such as explosions, gunfire, and firecrackers.

Gradually developing NIHL

Gradually developing NIHL refers to permanent cochlear damage from repeated exposure to loud sounds over a period of time. Unlike NIHL from acoustic trauma, this form of NIHL does not occur from a single exposure to a high-intensity sound pressure level. Gradually developing NIHL can be caused by multiple exposures to musical concerts, nightclubs, excessive noise in the workplace, and personal music devices. The U.S. Department of Labor’s Occupational Safety and Health Administration (OSHA) states that exposure to 90 dB(A) of noise, known as an exposure action value, for more than eight hours per day can result in permanent hearing loss (Occupational Health and Safety Administration [OSHA], 2002). Since decibels are based on a logarithmic scale, every increase of 3 decibels SPL results in a doubling of intensity, meaning hearing loss can occur at a faster rate. Therefore, gradually developing NIHL occurs from the combination of sound intensity and duration of exposure.

Both NIHL caused by acoustic trauma and gradually developing NIHL can often be characterized by a specific pattern presented in audiological findings. NIHL is generally observed to affect a person’s hearing sensitivity in the higher frequencies, especially at 4000 Hz. “Noise-induced impairments are usually associated with a notch-shaped high-frequency sensorineural loss that is worst at 4000 Hz, although the notch often occurs at 3,000 or 6,000 Hz, as well” (Gelfand, 2001, p. 202). Doctoral students at the University of Iowa have termed this notch, specific to a noise-induced etiology, a "muna." The symptoms of NIHL are usually presented equally in both ears (Gelfand). Not all audiological results from patients with NIHL match the above description. Often a decline in hearing sensitivity will occur at frequencies other than at the typical 3000-6000 Hz range. Variations arise from differences in people’s ear canal resonance, the frequency of the harmful acoustic signal, and the length of exposure (Rösler, 1994). As harmful noise exposure continues, the commonly affected frequencies will broaden and worsen in severity (Gelfand). “NIHL usually occurs initially at high frequencies (3k, 4k, or 6k Hz), and then spreads to the low frequencies (0.5k, 1k, or 2k Hz)” (Chen, 2003, p. 55).

Prevention

NIHL can easily be prevented through the use of some of the most simple, widely available and economical tools. This includes but is not limited to ear protection (i.e. earplugs and earmuffs), education, and hearing conservation programs. Earplugs and earmuffs can provide the wearer with at least 5 to 10 dB SPL of attenuation (Gelfand, 2001). According to a survey by Lass, Woodford, C. Lundeen, D. Lundeen and Everly-Myers (1987), which examined high school students’ attitudes and knowledge concerning hearing safety, 66% of the subjects reported a positive response to wearing hearing protection devices if educated about NIHL. Unfortunately, more often than not, individuals will avoid the use of ear protection due to embarrassment, lack of comfort, and reduced sound quality.

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However, the effectiveness of hearing protection programs is hindered by poor compliance in the use of hearing protection devices due to communication difficulties, comfort issues, individuals’ attitudes about protecting themselves from noise-induced hearing loss, and individuals’ perceptions about how others who do not use hearing protection will view them if they choose to use hearing protection. (Fausti et al., 2005, p. 51)

”

Workplace Standards

The Occupational Safety and Health Administration (OSHA) describes standards for occupational noise exposure in articles 1910.95 and 1926.52. OSHA states that an employer must implement hearing conservation programs for employees if the noise level of the workplace is equal to or above 85 dB(A) for an averaged 8-hour time period (Gelfand, 2001). OSHA also states that "exposure to impulsive or impact noise should not exceed 140 dB peak sound pressure level" (CFR 1910.95(b)(2)). The United States Department of Defense (DoD) instruction 605512 has some differences from OSHA 1910.95 standard. OSHA 1910.95 has a Permissible Exposure Limit of 90 dBA for an hour eight hour period, while the DoD has a Permissible Exposure Limit of 85 dBA for an eight hour period. Additionally, OSHA 1910.95 uses a 5 dB exchange rate and DoD instruction 605512 uses a 3 dB exchange rate.

“Hearing conservation programs in the workplace and in the general population seek to increase compliance and effectiveness of hearing protection protocols through audiometric screening tests and education on the dangers of noise exposure” (Fausti et al., 2005, p. 51).

Employees are required to wear hearing protection when it is identified that their 8-hour TWA is above the exposure action value of 85 dB. If subsequent monitoring shows that 90 dB is not surpased for an 8-hour TWA the employee is no longer required to wear hearing protection (OSHA 3074, 2002 (Revised)).

Few companies have emerged offering solutions for employers wishing to comply with the myriad regulations regarding hearing protection. One such company is Tomorrow's Safety Today.

Mitigation

For people living with NIHL, there are several management options that can improve the ability to hear and effectively communicate. Management programs for people with NIHL include counseling and the use of hearing aids and FM systems. With proper amplification and counseling, the prognosis is excellent for people with NIHL. The prognosis has improved with the recent advancements in digital hearing aid technology, such as directional microphones, open-fit hearing aids, and more advanced algorithms. Annual audiological evaluations are recommended to monitor any changes in a patient’s hearing and to modify hearing-aid prescriptions. There are no medical options at present for a person with NIHL. However, current research for the possible use of drug and genetic therapies look hopeful (National Institute on Deafness and Other Communication Disorders [NIDCD], 2006).

Hearing loss with craniofacial syndromes

Hearing loss with craniofacial syndromes is a common occurrence. Many of these multianomaly disorders involve structural malformations of the outer or middle ear, making a significant hearing loss highly likely.

Treacher Collins syndrome

Individuals with Treacher Collins syndrome often have both cleft palate and hearing loss, in addition to other disabilities. Hearing loss is often secondary to absent, small, or unusually formed ears (microtia), and commonly results from malformations of the middle ear. Researchers have found that most patients with Treacher Collins syndrome have symmetric external ear canal abnormalities and symmetrically dysmorphic or absent ossicles in the middle ear space. Inner ear structure is largely normal. Most patients show a moderate hearing impairment or greater, and the type of loss is generally a conductive hearing loss. Patients with Treacher Collins syndrome exhibit hearing losses similar to those of patients with malformed or missing ossicles (Pron et al., 1993).

Pierre Robin sequence

Persons with Pierre Robin sequence (PRS) are at greater risk for hearing impairment than persons with cleft lip and/or palate without PRS. One study showed an average of 83% hearing loss in PRS, compared to 60% in cleft individuals without PRS (Handzic et al., 1995). Similarly, PRS individuals typically exhibit conductive, bilateral hearing losses that are greater in degree than in cleft individuals without PRS. Middle ear effusion is generally apparent, with no middle ear or inner ear malformations. Accordingly, management by ear tubes (myringotomy tubes) is often effective and may restore normal levels of hearing (Handzic et al., 1995).

Stickler syndrome

The hearing loss most typical in patients with Stickler syndrome is a sensorineural hearing loss, indicating that the source of the deficit lies in the inner ear, the vestibulocochlear nerve, or the processing centers of the brain. Szymko-Bennett et al. (2001) found that the overall hearing loss in Type I Stickler Syndrome is generally mild and is not significantly progressive. Hearing loss is more common in the higher frequencies, from about 4000-8000 Hz (Szymko-Bennett et al., 2001). This mildly progressive sensorineural loss, or more significant losses (associated with Types II and III Stickler syndrome) is present in about 80% of patients with Stickler syndrome. However, other patients are also susceptible to conductive losses, similar to nonsyndromic cleft patients (Peterson-Falzone et al., 2001).

Apert Syndrome

Patients with Apert syndrome have a high occurrence of middle ear disease, otitis media and conductive hearing loss (Perterson-Fazone et al., 2001). Conductive hearing loss is frequently seen in this population due to almost constant middle ear disease (Gould et al., 1982).

Crouzon Syndrome

Patients with Crouzon syndrome sometimes exhibit malformations of the external ear and/or the middle ear, such as malalignment of the pinna (Peterson-Falzone et al., 2001). Literature has suggested that persons with Crouzon syndrome typically have conductive hearing loss caused by middle ear effusion (or fluid in the middle ear) and perforation to ossicular fixation (ossicles), intratympanic bony masses (tympanic membrane), ossicular anomalies (anomaly), and closure of the oval window. Patients with a sensorineural hearing loss have also been reported, but are less likely to occur.

Pfeiffer syndrome

A conductive hearing loss along with middle ear disease is most commonly seen in patients with Pfeiffer syndrome; although, there have been reports of mixed hearing loss as well. The hearing loss is most typically caused by stenosis or atresia of the auditory canal, middle ear hypoplasia, and ossicular hypoplasia (Vallino-Napoli, 1996).

Ectrodactyly-ectrodermal dysplasia-cleft syndrome

Conductive hearing loss has been reported by many with ectrodactyly-ectodermal dysplasia-cleft (EEC) syndrome in association with a cleft palate (Perterson-Falzone, 2001).

Saethre-Chotzen Syndrome

In Saethre-Chotzen syndrome the ears may be low set, posteriorly rotated, have other minor anomalies, and there may be a presence of a conductive hearing loss or a mixed hearing loss (Perterson-Falszone, 2001). Hearing loss in this group can also be caused by middle ear disease when a cleft palate is present (http://www.worldcf.org/chotzen.cfm).

Velocardiofacial Syndrome

About 70% of individuals with velocardiofacial syndrome (VCFS) have minor auricular malformations, or malformations of the ear. In this syndrome, the ears are typically low-set and somewhat posteriorly rotated. In addition to external malformations, individuals with VCFS are more vulnerable to otitis media because of the presence of a cleft or other form of velopharyngeal inadequacy. The hearing loss associated with VCFS is conductive when otitis media is present (Peterson-Falzone et al., 2001). There are also sporadic reports of sensorineural hearing loss and a mixed hearing loss. Of individuals with VCFS who have a hearing loss, only 11% had a sensorineural loss and 5% a mixed loss (Reyes et al., 1999).

Hemifacial microsomia

Individuals with hemifacial microsomia, also called oculoauriculo-vertebral spectrum, often have ear malformations. These malformations can be in the form of preauricular ear pits, complete absence of the auricle, stenosis or atresia of the external auditory canal, ossicular malformations, middle ear deformities, and incomplete pneumatization of the temporal bone. Rahbar et al. (2001) found that 95% of individuals with this syndrome have an ear malformation of some type. In addition to ear malformations, a conductive hearing loss can be present, typically ranging from mild to severe. There are also reported cases of cochlear involvement and sensorineural hearing loss. Rahbar et al. (2001) found that 86% of patients with Hemifacial Microsomia have a conductive hearing loss and 10% have a sensorineural hearing loss. There is no correlation between the severity of dysmorphic features and the degree of hearing loss, meaning individuals with mild malformations can have severely impaired hearing.

Nager syndrome

Individuals with Nager syndrome typically have the malformations of the auricle, external auditory canal, and middle ear, including the ossicles. These malformations were found in 80% of individuals with Nager syndrome. Inner ear malformations, however, are not typically seen in this population. Middle ear disease is common among individuals with Nager syndrome. Chronic otitis media and Eustachian tube deformity can result in conductive hearing loss. For this reason, early detection and treatment for middle ear disease is crucial in this population. Sensorineural hearing loss is not a typical characteristic of Nager syndrome; however, a subset of individuals present with a mixed hearing loss, due to a progressive sensorineural component combined with the typical conductive hearing loss (Herrman et al., 2005).

Health care

Health care, or healthcare, is the prevention, treatment, and management of illness and the preservation of mental and physical well being through the services offered by the medical, nursing, and allied health professions. Health care embraces all the goods and services designed to promote health, including “preventive, curative and palliative interventions, whether directed to individuals or to populations”. The organised provision of such services may constitute a health care system. This can include specific governmental organizations such as, in the UK, the National Health Service or a cooperation across the National Health Service and Social Services as in Shared Care. Before the term "health care" became popular, English-speakers referred to medicine or to the health sector and spoke of the treatment and prevention of illness and disease.

In most developed countries and many developing countries health care is provided to everyone regardless of their ability to pay. The National Health Service, established in 1948 by Clement Atlee's Labour government in the United Kingdom, were the world's first universal health care system provided by government and paid for from general taxation. Alternatively, compulsory government funded health insurance with nominal fees can be provided, as in Italy. Other examples are Medicare in Australia, established in the 1970s by the Labor government, and by the same name Medicare was established in Canada between 1966 and 1984. Universal health care contrasts to the systems like health care in the United States or South Africa, though South Africa is one of the many countries attempting health care reform. The United States is the only wealthy, industrialized nation that does not provide universal health care.

The United States is alone among developed nations with the absence of a universal health care system.^[10][11] Healthcare in the U.S. does, however, have significant publicly funded components. Medicare covers the elderly and disabled with a historical work record, Medicaid is available for some, but not all of the poor, and the State Children's Health Insurance Program covers children of low-income families. The Veterans Health Administration directly provides health care to U.S. military veterans through a nationwide network of government hospitals; while active duty service members, retired service members and their dependents are eligible for benefits through TRICARE. Together, these tax-financed programs cover about 27% of the population and make the government the largest health insurer in the nation. In 2001, only the governments of Iceland and Norway spent more per capita on healthcare. This care is generally provided by privately owned hospitals or physicians in private practice, but public hospitals are common in older cities. Just under 60% of Americans receive health insurance through an employer, although this number is declining and the employee's expected contribution to these plans varies widely and is increasing as costs escalate. A significant and growing number of people cannot obtain health insurance through their employer or are unable to afford individual coverage. Currently, the U.S. Census Bureau estimates that 16% of the U.S. population, or 47 million people, are uninsured. More than a third of the uninsured are in households earning $50,000 or more per year. Some uninsured are people under age 30 who don't believe they need to purchase health care; others are eligible for Medicaid but have not applied. The cost of medicines is frequently not covered by insurance, and some U.S. citizens travel to Canada and Mexico for drug purchases at prices far below those in their home areas. A few states have taken serious steps toward universal health care coverage, most notably Minnesota and Massachusetts, with a recent example being the Massachusetts 2006 Health Reform Statute.^[15] Other states, while not attempting to insure all of their residents, cover large numbers of people by reimbursing hospitals and other health-care providers using what is generally characterized as a charity care scheme; New Jersey is perhaps the best example of a state that employs the latter strategy. It is typical for most forms of general liability insurance sold in the U.S., such as home, automobile, or business insurance to have a significant premium allocation for medical damages. The U.S. legal system, which has the highest number of attorneys per capita of any country in the world, is available to assist in proving liability and collecting the money for medical bills from such insurances.

The Indian Health Service provides public funded care for indigenous peoples. Employer benefit based health insurance remains quite common with larger employers. Workers injured on the job are covered by government mandated worker compensation insurance and wage replacement benefits. These benefits vary considerably state-to-state and employers bear the cost of this insurance. Businesses with considerable risks, such as bridge-building, mining, or meat processing face far higher worker compensation insurance costs than do office based clerical businesses. Although the Medical colleges and research institutes form a backbone structure for providing healthcare, the private hospitals and nursing homes also are becoming an increasingly necessary part of the healthcare structure in the country.

Source From : www.wikipedia.org

HEARING PROBLEMS AND CARES

You know what hearing is, but what is hearing loss? Hearing loss, or hearing impairment (say: im-pare-ment), happens when there is a problem with one or more parts of the ear or ears. Someone who has hearing loss or impairment may be able to hear some sounds or nothing at all. Impairment means something is not working correctly or as well as it should. People also may use the words deaf, deafness, or hard of hearing when they're talking about hearing loss.

About 3 in 1,000 babies are born with hearing impairment, making it the most common birth defect. A hearing problem can also develop later in life. To understand how and why hearing loss happens, it helps to know how the ear works.

How Hearing Works

The ear is made up of three different sections: the outer ear, the middle ear, and the inner ear. These parts work together so you can hear and process sounds. The outer ear, or pinna (the part you can see), picks up sound waves and the waves then travel through the outer ear canal.

When the sound waves hit the eardrum in the middle ear, the eardrum starts to vibrate. When the eardrum vibrates, it moves three tiny bones in your ear. These bones are called the hammer (or malleus), anvil (or incus), and stirrup (or stapes). They help sound move along on its journey into the inner ear.

The vibrations then travel to the cochlea, which is filled with liquid and lined with cells that have thousands of tiny hairs on their surfaces. There are two types of hair cells: the outer and inner cells. The sound vibrations make the tiny hairs move. The outer hair cells take the sound information, amplify it (make it louder), and tune it. The inner hair cells send the sound information to your hearing nerve, which then sends it to your brain, allowing you to hear.

Types of Hearing Loss

There are a few different types of hearing loss: conductive, sensory, mixed (conductive and sensory combined), and neural.

• Conductive (say: kun-duk-tiv) hearing loss. This happens when there is a problem with a part of the outer or middle ear. Most kids with conductive hearing loss have a mild hearing loss and it is usually temporary because in most cases medical treatment can help.
• Sensory (say: sen-suh-ree) hearing loss. This happens when the cochlea is not working correctly because the tiny hair cells are damaged or destroyed. Depending on the loss, a kid may be able to hear most sounds (although they would be muffled); may be able to hear in quiet but not in noise; only some sounds; or no sounds at all. Sensory hearing impairment is almost always permanent and a kid's ability to talk normally may be affected.
• Neural (say: nur-ul) hearing loss. This happens when there is a problem with the connection from the cochlea to the brain. Neural means related to nerve, so neural hearing loss means the nerve that carries the messages from the cochlea to the brain is damaged.

What Causes Hearing Loss?

Hearing loss can happen because a person was born with parts of the ear that didn't form correctly and don't work well. Other problems can happen later because of an injury or illness, including:

• middle ear fluid
• serious infections, such as meningitis
• head injury
• listening to very loud music, especially through headphones
• repeated exposure to loud sounds, such as machinery

Lots of kids have had ear infections, which also can cause hearing loss. Permanent hearing loss is rare from an ear infection, but you need to visit the doctor if you or your parents suspect you have one.

How Does a Doctor Test for Hearing Loss?

If a doctor thinks that a baby or child may have hearing loss, the doctor will recommend that the parents take him or her to an audiologist. An audiologist (say: awd-ee-ah-luh-jist) is someone who is specially trained to test and help with the problems related to hearing loss.

A pediatric audiologist tests a child's hearing by doing different types of tests. They even have hearing tests for babies! Maybe you've had a hearing test, when you wore headphones and had to raise your left or right hand to show that you could hear in each ear.

If an audiologist finds that a child has hearing loss, he or she will recommend treatment and suggest the family work with a special team. This team can help figure out the best way for the kid to learn and communicate.

How Is Hearing Loss Treated?

The kind of treatment depends on the type of hearing loss, how severe it is, and the child's other needs. Common treatments include medicine, operations, hearing aids, or assistive listening devices, which emphasize voices and help kids hear better in noisy settings. With treatment, most kids will be able to hear normally again.

Hearing aids are kind of like tiny amplifiers. They help someone hear sounds better and can even pick up the sounds so that what kids hear is more clear. Hearing aids deliver amplified sounds (via sound vibrations) from the eardrum and middle ear to the inner ear or cochlea. Hearing aid technology is available that can adjust the volume of sounds automatically.

For some kids who are not able to hear or understand words even with the help of hearing aids, there is a device called a cochlear implant (say: ko-klee-ur im-plant). This is a very tiny piece of electronic equipment that is put into the cochlea during an operation. It takes over the job of the damaged or destroyed hair cells in the cochlea by turning sounds into electrical signals that stimulate the hearing nerve directly.

Learning and Communicating

A kid with hearing loss may attend a special school, special classes within a regular school, or may be part of a regular classroom. Depending on how severe their hearing loss is, some kids may work with audiologists or speech-language pathologists to help them develop their hearing and speaking skills. Some people with hearing loss may need to use special techniques like these to communicate:

• speechreading, which involves looking closely at a person's lips, facial expressions, and gestures to help figure out spoken words
• American Sign Language, or ASL, which is a language of hand movements that allows deaf people to communicate with one another without speaking

What about talking on the phone? Thanks to a telecommunication device, also called a TDD, a conversation can be typed out instead of spoken. The messages appear on a special screen or on a printout.

You might wonder how a hearing-impaired person could see a movie or watch TV. Closed-captioned TV shows and movies provide text at the bottom of the screen, so people with hearing loss can read along to follow the action.

So hearing-impaired kids can go to school, talk on the phone, and watch a movie. If that sounds a lot like a typical kid's life, you're right!

Reviewed by: Robert C. O'Reilly, MD, and Thierry Morlet, PhD
Date reviewed: June 2006
Originally reviewed by: Steven Dowshen, MD