HEARING CONSERVATION--PROTECT YOUR HEARING

NOISE INDUCED HEARING LOSS

NIHL can be caused by a one-time exposure to loud sound as well as by repeated exposure to sounds at various loudness levels over an extended period of time. The loudness of sound is measured in units called decibels. For example, normal conversation is approximately 60 decibels, the humming of a refrigerator is 40 decibels, and city traffic noise can be 80 decibels. Examples of sources of loud noises that cause NIHL are motorcycles, firecrackers, and firearms, all emitting sounds from 120 to 140 decibels. Sounds of less than 80 decibels, even after long exposure, are unlikely to cause hearing loss.

Exposure to harmful sounds causes damage to the sensitive hair cells of the inner ear as well as the hearing nerve. These structures can be injured by two kinds of noise: loud impulse noise, such as an explosion, or loud continuous noise, such as that generated in a woodworking shop.
Impulse sound can result in immediate hearing loss that may be permanent. The structures of the inner ear may be severely damaged. This kind of hearing loss may be accompanied by tinnitus
a ringing, buzzing, or roaring in the ears or head, which may subside over time. Hearing loss and tinnitus may be experienced in one or both ears, and tinnitus may continue constantly or occasionally throughout a lifetime.

Continuous exposure to loud noise also can damage the structure of the hair cells, resulting in hearing loss and tinnitus. Exposure to impulse and continuous noise may cause only a temporary hearing loss. If the hearing recovers, the temporary hearing loss is called a temporary threshold shift. The temporary threshold shift largely disappears 16 to 48 hours after exposure to loud noise.

Both forms of NIHL can be prevented by the regular use of hearing protectors such as earplugs or earmuffs.

The symptoms of NIHL increase gradually over a period of continuous exposure. Sounds may become distorted or muffled, and it may be difficult for the person to understand speech. The individual may not be aware of the loss, but it can be detected by an audiologist through comprehensive hearing evaluation.

More than 30 million Americans are exposed to hazardous sound levels on a regular basis. Individuals of all ages, including children, adolescents, young adults, and older people, can develop NIHL. Exposure occurs in the workplace, in recreational settings, and at home. Noisy recreational activities include target shooting and hunting, snowmobiling, riding go-carts, woodworking and other noisy hobbies, and playing with power horns, cap guns, and model airplanes. Harmful noises at home include vacuum cleaners, garbage disposals, gas-powered lawn mowers, leaf blowers, and shop tools. And it makes no difference where a person lives--both urban and rural settings offer their own brands of noisy devices on a daily basis. Of the 28 million Americans who have some degree of hearing loss, about one-third can attribute their hearing loss, at least in part, to noise.

HEARING PROTECTION IN NOISE
Choose The Hearing Protection That's Right For You
by
Carol Merry Stephenson, Ph.D.,
National Institutes for Occupational Safety and Health
www.cdc.gov/niosh


Expandable foam plugs:
These plugs are made of a formable material designed to expand and conform to the shape of each person's ear canal. Roll the expandable plugs into a thin, crease-free cylinder. Whether you roll plugs with thumb and fingers or across your palm doesn't matter. What's critical is the final result-a smooth tube thin enough so that about half the length will fit easily into your ear canal. Some individuals, especially women with small ear canals, have difficulty rolling typical plugs small enough to make them fit. A few manufacturers now offer a small size expandable plug.


Pre-molded, reusable plugs:
Pre-molded plugs are made from silicone, plastic or rubber and are manufactured as either "one-size-fits-most" or are available in several sizes. Many pre-molded plugs are available in sizes for small, medium or large ear canals.


A critical tip about pre-molded plugs is that a person may need a different size plug for each ear. The plugs should seal the ear canal without being uncomfortable. This takes trial and error of the various sizes. Directions for fitting each model of pre-molded plug may differ slightly depending on how many flanges they have and how the tip is shaped. Insert this type of plug by reaching over your head with one hand to pull up on your ear. Then use your other hand to insert the plug with a gentle rocking motion until you have sealed the ear canal.
Advantages of pre-molded plugs are that they are relatively inexpensive, reusable, washable, convenient to carry, and come in a variety of sizes. Nearly everyone can find a plug that will be comfortable and effective. In dirty or dusty environments, you don't need to handle or roll the tips.


Canal caps:
Canal caps often resemble earplugs on a flexible plastic or metal band. The earplug tips of a canal cap may be a formable or pre-molded material. Some have headbands that can be worn over the head, behind the neck or under the chin. Newer models have jointed bands increasing the ability to properly seal the earplug.


The main advantage canal caps offer is convenience. When it's quiet, employees can leave the band hanging around their necks. They can quickly insert the plug tips when hazardous noise starts again. Some people find the pressure from the bands uncomfortable. Not all canal caps have tips that adequately block all types of noise. Generally, the canal caps tips that resemble stand-alone earplugs seem to block the most noise.


Earmuffs:
Earmuffs come in many models designed to fit most people. They work to block out noise by completely covering the outer ear. Muffs can be "low profile" with small ear cups or large to hold extra materials for use in extreme noise. Some muffs also include electronic components to help users communicate or to block impulsive noises.


Workers who have heavy beards or sideburns or who wear glasses may find it difficult to get good protection from earmuffs. The hair and the temples of the glasses break the seal that the earmuff cushions make around the ear. For these workers, earplugs are best. Other potential drawbacks of earmuffs are that some people feel they can be hot and heavy in some environments.


Miscellaneous devices:
Manufacturers are receptive to comments from hearing protection users. This has led to the development of new devices that are hybrids of the traditional types of hearing protectors. Because many people like the comfort of foam plugs, but don't want to roll them in dirty environments, a plug is now available that is essentially a foam tip on a stem. You insert this plug much like a pre-molded plug without rolling the foam.
Scientists are developing earmuffs using high-tech materials to reduce weight and bulk, but still effectively block noise. On the horizon may be earplugs with built in two-way communication capability.


Still, the best hearing protector is the one that is comfortable and convenient and that you will wear every time you are in an environment with hazardous noise.


ON-LINE HEARING TEST

This written test will direct your attention to the need to seek professional help.

Do you have a problem hearing over the telephone?
Yes No
Do you have trouble following the conversation when two or more people are talking at the same time?
Yes No
Do people complain that you turn the TV volume up too high?
Yes No
Do you have to strain to understand conversation?
Yes No
Do you have trouble hearing in a noisy background?
Yes No
Do you find yourself asking people to repeat themselves?
Yes No
Do many people you talk to seem to mumble (or not speak clearly)?
Yes No
Do you misunderstand what others are saying and respond inappropriately?
Yes No
Do you have trouble understanding the speech of women and children?
Yes No
Do people get annoyed because you misunderstand or are unable to hear what they say?
Yes No

If you answer "yes" to two or more items, there is a significant likelihood that you may have hearing loss. We suggest you consult an audiologist for a comprehensive hearing evaluation. See the links to the American Academy of Audiology or Academy of Dispensing Audiologists to find an audiologist in your area or contact us via this website.

COCHLEAR IMPLANTS
by Doug Beck, Au.D., Editor-in-Chief,
Healthyhearing http://www.healthyhearing.com

Generally speaking, cochlear implants are for patients with severe-to-profound, sensorineural hearing loss. There are approximately 500,000 patients in the USA with severe-to-profound hearing loss. Cochlear implants are only recommended after the patient has tried appropriately fitted hearing aids and has not shown sufficient benefit from hearing aids. Cochlear implants are devices that are "permanently" surgically implanted into the inner ear.

Cochlear implantation is a surgical procedure performed by otolaryngology surgeons. Cochlear implants have been approved for almost two decades and the advances and improvements in the technology have been amazing. The Food and Drug Association (FDA) and the American Medical Association (AMA) recognize cochlear implants as safe and effective treatment for severe-to-profound sensorineural hearing loss. Most insurance programs pay for cochlear implantation.

Appropriately identified adults as well as profoundly deaf children (aged 12 months or older) can be implanted. Research demonstrates that the earlier a deaf child is implanted, the better the long term result will be with respect to speech and language development. Following surgery, rehabilitation is necessary, as the child must learn to associate the sound signals with normal sounds. Regarding deaf adults, research suggests that adults who receive cochlear implants are less lonely, have less social anxiety, are more independent, have increased social and interpersonal skills, and of course, they hear better with the cochlear implant! The majority of cochlear implant recipients wearing digital cochlear implants are able to use the telephone.
Cochlear implants are utilized in the patient who cannot benefit from hearing aids. The cochlear implant is a device used to bypass the nonfunctional inner ear and converts sound into electrical impulses that directly stimulate the cochlear nerve. The implant consists of an external portion comprised of a microphone, sound processor, and external coil and an internal portion that must be surgically implanted.

The surgical procedure involves the placement of an internal receiver beneath the skin behind the ear, and a stimulating electrode array is inserted into the cochlea. The electrical signals are manipulated and controlled by the audiologist to maximize speech perception. The brain interprets these electrical impulses as sound. Again, not all patients are surgical candidates, and not all cochlear implant recipients receive the same benefit.
It is important to remember that the vast majority of patients who receive cochlear implants are actually "deaf" prior to implantation and they have not been successful with traditional hearing aids. Your audiologist is a very knowledgeable resource regarding cochlear implants and will be happy to discuss them with you.