A hearing aid is an electronic, battery-operated device that amplifies and changes sound to allow for improved communication. Hearing aids receive sound through a microphone, which then converts the sound waves to electrical signals. The amplifier increases the loudness of the signals and then sends the sound to the ear through a speaker.
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Hearing aids are like a special personalized amplifier, helping you to
hear. Hearing
aids contain three main components, which help
to make sounds come through louder and more clearly |
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The microphone The microphone picks up sound waves from the air and transforms them into electrical signals.
The amplifier The loudspeaker.
And that’s how hearing
aids help you hear better! |
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1: The microphone
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Approximately 28 million Americans have a hearing impairment. Hearing loss is one of the most prevalent chronic health conditions in the United States, affecting people of all ages, in all segments of the population, and across all socioeconomic levels. Hearing loss affects approximately 17 in 1,000 children under age 18. Incidence increases with age: approximately 314 in 1,000 people over age 65 have hearing loss. Hearing loss can be hereditary, or it can result from disease, trauma, or long-term exposure to damaging noise or medications. Hearing loss can vary from a mild but important loss of sensitivity, to a total loss of hearing.
There are different types of hearing loss. Conductive hearing loss occurs when sound waves are prevented from passing to the inner ear. This can be caused by a variety of problems including buildup of earwax (cerumen), infection, fluid in the middle ear (ear infection or otitis media), or a punctured eardrum. Sensorineural (nerve) hearing loss develops when the auditory nerve or hair cells in the inner ear are damaged by aging, noise, illness, injury, infection, head trauma, toxic medications, or an inherited condition. Mixed hearing loss is a combination of both conductive and sensorineural hearing loss. A conductive hearing loss can often be corrected with medical or surgical treatment, while sensorineural hearing loss usually cannot be reversed.
People with hearing loss may experience some or all of the following problems:
Difficulty hearing conversations, especially when there is background noise.
Hissing, roaring, or ringing in the ears (tinnitus).
Difficulty hearing the television or radio at a normal volume.
Fatigue and irritation caused by the effort to hear.
Dizziness or problems with balance.
If you think you might have hearing loss, visit your physician, who may refer you to an otolaryngologist or audiologist. An otolaryngologist is a physician who specializes in ear, nose, and throat disorders, and will investigate the cause of the hearing loss. An audiologist is a hearing health professional who identifies and measures hearing loss and will perform a hearing test to assess the type and degree of loss.
On the basis of the hearing test results, the audiologist can determine whether hearing aids will help. Hearing aids are particularly useful in improving the hearing and speech comprehension of people with sensorineural hearing loss. When choosing a hearing aid, the audiologist will consider your hearing ability, work and home activities, physical limitations, medical conditions, and cosmetic preferences. For many people, cost is also an important factor. You and your audiologist must decide whether one or two hearing aids will be best for you. Wearing two hearing aids may help balance sounds, improve your understanding of words in noisy situations, and make it easier to locate the source of sounds.
There are several types of hearing aids. Each type offers different advantages, depending on its design, levels of amplification, and size. Before purchasing any hearing aid, ask whether it has a warranty that will allow you to try it out. Most manufacturers allow a 30- to 60-day trial period during which aids can be returned for a refund.
There are four basic styles of hearing aids for people with sensorineural hearing loss:
In-the-Ear (ITE) hearing aids fit completely in the outer ear and are used
for mild to severe hearing loss. The case, which holds the components, is made
of hard plastic. ITE aids can accommodate added technical mechanisms such as a
telecoil, a small magnetic coil contained in the hearing aid that improves
sound transmission during telephone calls. ITE aids can be damaged by earwax
and ear drainage, and their small size can cause adjustment problems and
feedback. They are not usually worn by children because the casings need to be
replaced as the ear grows.
Behind-the-Ear (BTE) hearing aids are worn behind the ear and are connected to a plastic earmold that fits inside the outer ear. The components are held in a case behind the ear. Sound travels through the earmold into the ear. BTE aids are used by people of all ages for mild to profound hearing loss. Poorly fitting BTE earmolds may cause feedback, a whistle sound caused by the fit of the hearing aid or by buildup of earwax or fluid.
Canal Aids fit into the ear canal and are available in two sizes. The
In-the-Canal (ITC) hearing aid is customized to fit the size and shape of the
ear canal and is used for mild or moderately severe hearing loss. A
Completely-in-Canal (CIC) hearing aid is largely concealed in the ear canal
and is used for mild to moderately severe hearing loss. Because of their small
size, canal aids may be difficult for the user to adjust and remove, and may
not be able to hold additional devices, such as a telecoil. Canal aids can
also be damaged by earwax and ear drainage. They are not typically recommended
for children.
Body Aids are used by people with profound hearing loss. The aid is
attached to a belt or a pocket and connected to the ear by a wire. Because of
its large size, it is able to incorporate many signal processing options, but
it is usually used only when other types of aids cannot be used.
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The inside mechanisms of hearing aids vary among devices, even if they are
the same style. Three types of circuitry, or electronics, are used:
Using hearing aids successfully takes time and patience. Hearing aids will not restore normal hearing or eliminate background noise. Adjusting to a hearing aid is a gradual process that involves learning to listen in a variety of environments and becoming accustomed to hearing different sounds. Try to become familiar with hearing aids under nonstressful circumstances a few hours at a time. Programs are available to help users master new listening techniques and develop skills to manage hearing loss. Contact your audiologist for further information about programs that may suit your individual needs.
Before you buy a hearing aid, ask your audiologist these important questions:
Are there any medical or surgical considerations or corrections for my
hearing loss?
Which design is best for my hearing loss?
What is the total cost of the hearing aid?
Is there a trial period to test the hearing aids? What fees are
nonrefundable if they are returned after the trial period?
How long is the warranty? Can it be extended?
Does the warranty cover future maintenance and repairs?
Can the audiologist make adjustments and provide servicing and minor
repairs? Will loaner aids be provided when repairs are needed?
What instruction does the audiologist provide?
Can assistive devices such as a telecoil be used with the hearing aids?
What problems might I experience while adjusting to my hearing aids?
The following suggestions will help you care for your hearing aids:
The National Institute on Deafness and Other Communication Disorders (NIDCD) supports more than 30 grants for scientists to conduct studies on hearing aid research and development. These studies cover areas such as the application of new signal processing strategies and ways to improve sound transmission and reduce noise interference, as well as psychophysical studies of the impact of abnormal hearing function on speech recognition. Other studies focus on the best way to select and fit hearing aids in children and other difficult-to-test populations, and on reducing bothersome aspects such as feedback and the occlusion effect. Further research will determine the best ways to manipulate speech signals in order to enhance understanding.
To improve hearing aid performance, especially in noisy situations, NIDCD has entered into two collaborative ventures. The first was formed between NIDCD and the Department of Veterans Affairs (VA) to expand and intensify hearing aid research and development. The program includes a contract for the development of hearing aids as well as clinical trials. The knowledge gained will be used to help people choose the best hearing aid for their particular type of hearing impairment.
In the second collaboration, the National Aeronautics and Space Administration (NASA) and the VA have joined NIDCD in surveying all Federal laboratories for acoustic and electronic technologies that might improve hearing aids. The most promising technologies have been presented to auditory scientists and hearing aid manufacturers in the hope of forming research partnerships that will lead to commercial application of these technologies.
The
BAHA consists of three parts: a titanium implant, an
external abutment, and a sound processor. The system
works by enhancing natural bone transmission as a
pathway for sound to travel to the inner ear, bypassing
the external auditory canal and middle ear. The titanium
implant is placed during a short surgical procedure and
over time naturally integrates with the skull bone. For
hearing, the sound processor transmits sound vibrations
through the external abutment to the titanium implant.
The vibrating implant sets up vibrations within the
skull and inner ear that finally stimulate the nerve
fibers of the inner ear, allowing hearing.
Congenital
conductive hearing loss caused by a malformation of the
middle or external ear resulting in a missing or
incomplete ear canal (external auditory canal atresia)
are effectively managed with a BAHA. Traditionally
people with this type of hearing loss have been offered
an old-fashioned bone conducting hearing aid. These are
either held on the head using a steel spring headband or
included in the frame of a pair of glasses. Traditional
bone conductors have several disadvantages. The sound
quality is poor as the skin acts as a barrier for the
sound to travel to the inner ear. They are uncomfortable
- patients complain of pain and headaches due to the
constant pressure of the headband. They are also
cumbersome, obtrusive and insecure. 
One
ear does not provide adequate hearing in many
situations. Patients with severe hearing loss on one
side, but normal hearing in the other ear have
difficulty understanding speech in background noise
(such as group conversations and restaurants) and
determining which direction sound comes from. Unilateral
deafness can result from viral infections, trauma,
acoustic neuromas and other ear tumors and ear surgery.