Audiology

DOES THIS SOUND FAMILIAR?

Every evening when Mrs. Sprout and her husband watch television together she repeatedly asks him to turn up the volume. Recently, her friends have noticed that she often asks them to repeat what they have said, and sometimes she answers their questions inappropriately as if she is not even following the conversation. When Mrs. Jones goes to bed at night, she is aware of a ringing in her ears that makes it difficult to go to sleep.

Unfortunately, situations like Mrs. Sprouts' are all too common. More than 20 million Americans suffer some form of hearing impairment, many unaware that they may be helped.

Diagnostic Testing:

Audiometric Evaluations

Using specialized equipment in our two test booths, our audiologist can determine the ability to hear and discriminate sounds. A hearing evaluation includes a variety of subtests that can indicate the severity and type of hearing loss. Usually a hearing test will include evaluating the ability to understand speech. The Auditory Brainstem Response (ABR) is a painless electrode test used to evaluate the auditory system. With the ABR technology no one is too young or too old to have a hearing test.

Tests for Balance Disorders

The ear works with the eyes and spine to control balance. However, balance disorders may occur with or without a loss of hearing. Electronystagmography (ENG) testing uses electrodes placed on the head to record eye movements as the patient looks at various patterns and moves the head to different positions. The temperature of the ear canal is also changed to stimulate the inner ear, and eye movements are charted. ENG results are interpreted by physicians to help diagnose the cause of dizziness so that appropriate treatment can be implemented.

Facts about Otosclerosis

What is otosclerosis?

The term otosclerosis is derived from the Greek words for "hard" (scler-o) and "ear" (oto). It describes a condition of abnormal growth in the tiny bones of the middle ear, which leads to a fixation of the stapes bone. The stapes bone must move freely for the ear to work properly and hear well.

Hearing is a complex process. In a normal ear, sound vibrations are funneled by the outer ear into the ear canal where they hit the ear drum. These vibrations cause movement of the ear drum that transfers to the three small bones of the middle ear, the malleus (hammer), incus (anvil), and stapes (stirrup). When the stapes bone moves, it sets the inner ear fluids in motion, which, in turn, start the process to stimulate the auditory (hearing) nerve. The hearing nerve then carries sound energy to the brain, resulting in hearing of sound. When any part of this process is compromised, hearing is impaired.

Who gets otosclerosis and why?

It is estimated that ten percent of the adult Caucasian population is affected by otosclerosis. The condition is less common in people of Japanese and South American decent and is rare in African Americans. Overall, Caucasian, middle-aged women are most at risk.

The hallmark symptom of otosclerosis, slowly progressing hearing loss, can begin anytime between the ages of 15 and 45, but it usually starts in the early 20’s. The disease can develop in both women and men, but is particularly troublesome for pregnant women who, for unknown reasons, often experience a rapid decrease in hearing ability.

Approximately 60 percent of otosclerosis cases are genetic in origin. On average, a person who has one parent with otosclerosis has a 25 percent chance of developing the disorder. If both parents have otosclerosis, the risk goes up to 50 percent.

What are the symptoms?

Gradual hearing loss is the most frequent symptom of otosclerosis. Often, individuals with otosclerosis will first notice that they cannot hear low-pitched sounds or whispers. Other symptoms of the disorder can include dizziness, balance problems, or a sensation of ringing, roaring, buzzing, or hissing in the ears or head known as tinnitus.

How is it diagnosed?

Because many of the symptoms typical of otosclerosis can also be caused by other medical conditions, it is important to be examined by an otolaryngologist (ear, nose and throat doctor) to eliminate other possible causes of the symptoms. After an ear exam, the otolaryngologist may order a hearing test. Based on the results of this test and the exam findings, the otolaryngologist will suggest treatment options.

How is it treated?

If the hearing loss is mild, the otolaryngologist may suggest continued observation and a hearing aid to amplify the sound reaching the ear drum. Sodium fluoride has been found to slow the progression of the disease and may also be prescribed. In most cases of otosclerosis, a surgical procedure called stapedectomy is the most effective method of restoring or improving hearing.

What is a stapedectomy?

A stapedectomy is an outpatient surgical procedure done under local or general anesthesia through the ear canal with an operating microscope. (No outer incisions are made.) It involves removing the immobilized stapes bone and replacing it with a prosthetic device. The prosthetic device allows the bones of the middle ear to resume movement, which stimulates fluid in the inner ear and improves or restores hearing.

Modern-day stapedectomies have been performed since 1956 with a success rate of 90 percent. In rare cases (about one percent of surgeries), the procedure may worsen hearing.

Otosclerosis affects both ears in eight out of ten patients. For these patients, ears are operated on one at a time; the worst hearing ear first.

What should I expect after a stapedectomy?

Most patients return home the evening after surgery and are told to lie quietly on the un-operated ear. Oral antibiotics may be prescribed by the otolaryngologist. Some patients experience dizziness the first few days after surgery. Taste sensation may also be altered for several weeks or months following surgery, but usually returns to normal.

Following surgery, patients may be asked to refrain from nose blowing, swimming, or other activities that may get water in the operated ear. Normal activities (including air travel) are usually resumed two weeks after surgery.

Notify your otolaryngologist immediately if any of the following occurs:

• Sudden hearing loss
• Intense pain
• Prolonged or intense dizziness
• Any new symptom related to the operated ear

Since packing is placed in the ear at the time of surgery, hearing improvement will not be noticed until it is removed about a week after surgery. The ear drum will heal quickly, generally reaching the maximum level of improvement within two weeks.

Your Genes and Hearing Loss

Your Genes and Hearing Loss

One of the most common birth defects is hearing loss or deafness (congenital), which can affect as many as three of every 1,000 babies born. Inherited genetic defects play an important role in congenital hearing loss, contributing to about 60 percent of deafness occurring in infants. Although exact data is not available, it is likely that genetics plays an important role in hearing loss in the elderly. Inherited genetic defects are just one factor that can lead to hearing loss and deafness, both of which may occur at any stage of a person’s lifespan. Other factors may include: medical problems, environmental exposure, trauma, and medications.

The most common and useful distinction in hearing impairment is syndromic versus non-syndromic.

• Non-syndromic hearing impairment accounts for the vast majority of inherited hearing loss, approximately 70 percent. Autosomal- recessive inheritance is responsible for about 80 percent of cases of non-syndromic hearing impairment, while autosomal-dominant genes cause 20 percent, less than two percent of cases are caused by X-linked and mitochondrial genetic malfunctions.

• Syndromic(sin-DRO-mik) means that the hearing impairment is associated with other clinical abnormalities. Among hereditary hearing impairments, 15 to 30 percent are syndromic. Over 400 syndromes are known to include hearing impairment and can be classified as: syndromes due to cyotgenetic or chromosomal anomalies, syndromes transmitted in classical monogenic or Mendelian inheritance, or syndromes due to multi-factorial influences, and finally, syndromes due to a combination of genetic and environmental factors.

Variable expression of different aspects of syndromes is common. Some aspects may be expressed in a range from mild to severe or different combinations of associated symptoms may be expressed in different individuals carrying the same mutation within a single pedigree. An example of variable expressivity is seen in families transmitting autosomal dominant Waardenburg syndrome. Within the same family, some affected members may have dystopia canthorum (an unusually wide nasal bridge due to sideways displacement of the inner angles of the eyes), white forelock, heterochromia irides (two different-colored irises or two colors in the same iris), and hearing loss, while others with the same mutation may only have dystopia canthorum.

How do genes work?

Genes are a road map for the synthesis of proteins, which are the building blocks for everything in the body: hair, eyes, ears, heart, lung, etc. Every child inherits half of its genes from one parent and half from the other parent. If the inherited genes are defective, a health disorder such as hearing loss or deafness can result. Hearing disorders are inherited in one of four ways:

Autosomal Dominant Inheritance: For autosomal dominant disorders, the transmission of a rare allele of a gene by a single heterozygous parent is sufficient to generate an affected child. A heterozygous parent has two types of the same gene (in this case, one mutated and the other normal) and can produce two types of gametes (reproductive cells). One gamete will carry the mutant form of the gene of interest, and the other the normal form. Each of these gametes then has an equal chance of being used to form the offspring. Thus the chance that the offspring of a parent with an autosomal dominant gene will develop the disorder is 50 percent. Autosomal dominant traits usually affect males and females equally.

Autosomal Recessive Inheritance: An autosomal recessive trait is characterized by having parents who are heterozygous carriers for mutant forms of the gene in question but are not affected by the disorder. The problem gene that would cause the disorder is suppressed by the normal gene. These heterozygous parents (A/a) can each generate two types of gametes, one carrying the mutant copy of the gene (a) and the other having a normal copy of the gene (A). There are four possible combinations from each of the parents, A/a, A/A, a/A, and a/a. Only the offspring that inherits both mutant copies (a/a) will exhibit the trait. Overall, offspring of these two parents will face a 25 percent chance of inheriting the disorder.

X-linked Inheritance: A male offspring has an X chromosome and a Y chromosome, while a female has two copies of the X chromosome only. Each female inherits an X chromosome from her mother and her father. On the other hand, each male inherits an X chromosome from his mother and a Y chromosome from his father. In general, only one of the two X chromosomes carried by a female is active in any one cell while the other is rendered inactive. This is why when a female inherits a defective gene on one X chromosome, the normal gene on the other X chromosome can usually compensate. As males only have one copy of the X chromosome, any defective gene is more likely to manifest into a disorder.

Mitochondrial Inheritance: Mitochondrias, small powerhouses within each cell, also contain their own DNA. Interestingly, the sperm does not have any mitochondria, and consequently, only the mitochondria in the egg from the mother can be passed from one generation to the next. This leads to an interesting inheritance pattern where only affected mothers (and not affected fathers as their sperms do not have mitochondria) can pass on a disease from one generation to the next. Sensitivity to aminoglycoside antibiotics can be inherited through a defect in mitochondrial DNA and is the most common cause of deafness in China!

In the last decade, advances in molecular biology and genetics have contributed substantially to the understanding of development, function, and pathology of the inner ear. Researchers have identified several of the various genes responsible for hereditary deafness or hearing loss, most notably the GJB2 gene mutation. As one of the most common genetic causes of hearing loss, GJB2-related hearing loss is considered a recessive genetic disorder because the mutations only cause deafness in individuals who inherit two copies of the mutated gene, one from each parent. A person with one mutated copy and one normal copy is a carrier but is not deaf. Screening tests for the GJB2 gene are available for at risk individuals to help them determine their risk of having a child with hearing problems.

© 2004 AAO-HNS/AAO-HNSF

Hearing Aids Through the Ages

Hearing aids in their various forms have provided needed amplification of sound for many persons experiencing hearing loss. Explore the virtual exhibit.

© 2004 AAO-HNS/AAO-HNSF

Buying a Hearing Aid

Answers to common questions

I don't hear well. What should I do? What should I expect?

Because some hearing problems can be medically corrected, first visit a physician who can refer you to an otolaryngologist (an ear, nose, and throat specialist). If you have ear pain, drainage, excess earwax, hearing loss in only one ear, sudden or rapidly progressive hearing loss, or dizziness, it is especially important that you see an otolaryngologist. Then, get a hearing assessment from an audiologist (a nonphysician health care professional). A screening test from a hearing aid dealer may not be adequate. Many otolaryngologists have an audiologist associate in their office who will assess your ability to hear pure tone sounds and to understand words. The results of these tests will show the degree of hearing loss and whether it is conductive or sensorineural and may give other medical information about your ears and your health.

Where do I go to get hearing aids?

Because federal regulation prohibits any hearing aid sale unless the buyer has first received a medical evaluation from a physician, you will need to see your physician before you purchase a hearing aid(s). However, the regulation says that if you are more than 18 years old and are aware of the recommendation to receive a medical exam, you may sign a waiver to forego the exam. An otolaryngologist, audiologist, or an independent dispenser can dispense aids. Hearing aids should be custom fitted to your ear and hearing needs. Hearing aids purchased by mail-order typically cannot be custom fitted.
Conductive Hearing Loss

A hearing loss is conductive when there is a problem with the ear canal, the eardrum and/or the three bones connected to the eardrum. Common reasons for this type of hearing loss are a plug of excess wax in the ear canal or fluid behind the eardrum. Medical treatment or surgery may be available for these and more complex forms of conductive hearing loss.

Sensorineural Hearing Loss

A hearing loss is sensorineural when it results from damage to the inner ear (cochlea) or auditory nerve, often as a result of the aging process and/or noise exposure. Sounds may be unclear and/or too soft. Sensitivity to loud sounds may occur. Medical or surgical intervention cannot correct most sensorineural hearing losses. However, hearing aids may help you reclaim some sounds that you are missing as a result of nerve deafness.

How expensive are hearing aids?

Hearing aids vary in price according to style, electronic features, and local market conditions. Price can range from many hundreds of dollars to more than $2,500 for a programmable, digitalized hearing aid. Purchase price should not be the only consideration in buying a hearing aid. Product reliability can save repair costs and the frustration of a malfunctioning hearing aid.

What kinds of hearing aids are available?

There are several styles of hearing aids:

• Behind-the-ear (BTE) hearing aids are placed over the ear and connected with tubing to custom-fitted earpieces.
• In-the-ear (ITE) hearing aids fill the entire bowl of the ear and part of the ear canal.
• Smaller versions of ITEs are called half-shell and in-the-canal (ITC).
• The least visible aids are completely-in-the-canal (CIC).

Hearing aid options, which are appropriate for your particular hearing loss and listening needs, the size, and shape of your ear and ear canal, and the dexterity of your hands will all be considered in deciding what type of hearing aid is the best for you. Many hearing aids have special telecoil "T" switches to aid in use of the telephone and certain public sound systems. Discuss your need for a T-coil switch while you are considering hearing aid options.

Will I need a hearing aid for each ear?

Usually, if you have hearing loss in both ears, using two hearing aids is best. Listening in a noisy environment is difficult with amplification in one ear only, and it is more difficult to distinguish where sounds are coming from. If, however, the quality of hearing in one ear is very different from the other, one hearing aid may be better than two.

What other questions should I ask?

• Ask about charges for the hearing evaluation, dispensing fee(s), and future servicing and repair.
• Inquire about the trial period policy and what fees are refundable if you return the hearing aid(s) during the trial period.
• Ask about the warranty coverage for your hearing aids and the consumers' protection program for hearing aid purchasers in your state.

What will happen at my hearing aid fitting?

• The hearing aids will be fitted for your ears.
• Then, while wearing your hearing aids, you will be tested for word understanding in quiet and in noise and for improvement in hearing tones.
• Next, you will receive instruction about the care of your hearing aids, the batteries used to power them, a suggested wearing schedule, general expectations, and helpful communication strategies.
• You will also practice properly inserting and removing the hearing aids and batteries.

How should I begin wearing the aids?

• Start using your hearing aids in quiet surroundings, gradually building up to noisier environments.
• Note where and when that you find the hearing aids beneficial.
• Be patient and allow yourself to get used to the aids and the "new" sounds they allow you to hear.
• Keep a diary to help you remember your experiences.
• Report any concerns on a follow-up appointment.

© 2004 AAO-HNS/AAO-HNSF

Doctor, What Causes Tinnitus?

I sometimes hear ringing in my ears. Is this unusual?

Not at all. Tinnitus is the name for these head noises, and they are very common. Nearly 36 million Americans suffer from this discomfort. Tinnitus may come and go, or you may be aware of a continuous sound. It can vary in pitch from a low roar to a high squeal or whine, and you may hear it in one or both ears. When the ringing is constant, it can be annoying and distracting. More than seven million people are afflicted so severely that they cannot lead normal lives.

Can other people hear the noise in my ears?

Not usually, but sometimes they are able to hear a certain type of tinnitus. This is called "objective tinnitus," and it caused either by abnormalities in blood vessels around the outside of the ear or by muscle spasms, which may sound like clicks or crackling inside the middle ear.

What causes tinnitus?

Most tinnitus comes from damage to the microscopic endings of the hearing nerve in the inner ear. The health of these nerve endings is important for acute hearing, and injury to them brings on hearing loss and often tinnitus. If you are older, advancing age is generally accompanied by a certain amount of hearing nerve impairment and tinnitus. If you are younger, exposure to loud noise is probably the leading cause of tinnitus, and often damages hearing as well.

There are many causes for "subjective tinnitus," the noise only you can hear. Some causes are not serious (a small plug of wax in the ear canal might cause temporary tinnitus). Tinnitus can also be a symptom of stiffening of the middle ear bones (otosclerosis).

Tinnitus may also be caused by allergy, high or low blood pressure (blood circulation problems), a tumor, diabetes, thyroid problems, injury to the head or neck, and a variety of other causes including medications such as anti-inflammatories, antibiotics, sedatives, antidepressants, and aspirin. If you take aspirin and your ears ring, talk to your doctor about dosage in relation to your size.

Treatment will be quite different in each case of tinnitus. It is important to see an otolaryngologist to investigate the cause of your tinnitus so that the best treatment can be determined.

What is the treatment?

In most cases, there is no specific treatment for ear and head noise. If your otolaryngologist finds a specific cause of your tinnitus, he or she may be able to eliminate the noise. But, this determination may require extensive testing including X-rays, balance tests, and laboratory work. However, most causes cannot be identified. Occasionally, medicine may help the noise. The medications used are varied, and several may be tried to see if they help.

The following list of DOs and DON'Ts can help lessen the severity of tinnitus:

• Avoid exposure to loud sounds and noises.
• Get your blood pressure checked. If it is high, get your doctor's help to control it.
• Decrease your intake of salt. Salt impairs blood circulation.
• Avoid stimulants such as coffee, tea, cola, and tobacco.
• Exercise daily to improve your circulation.
• Get adequate rest and avoid fatigue.
• Stop worrying about the noise. Recognize your head noise as an annoyance and learn to ignore it as much as possible.

What can help me cope with tinnitus?

Concentration and relaxation exercises can help to control muscle groups and circulation throughout the body. The increased relaxation and circulation achieved by these exercises can reduce the intensity of tinnitus in some patients.

Masking. Tinnitus is usually more bothersome in quiet surroundings. A competing sound at a constant low level, such as a ticking clock or radio static (white noise), may mask the tinnitus and make it less noticeable. Products that generate white noise are also available through catalogs and specialty stores.

Hearing Aids. If you have a hearing loss, a hearing aid(s) may reduce head noise while wearing it and sometimes cause it to go away temporarily. It is important not to set the hearing aid at excessively loud levels, as this can worsen the tinnitus in some cases. However, a thorough trial before purchase of a hearing aid is advisable if your primary purpose is the relief of tinnitus.

Tinnitus maskers can be combined within hearing aids. They emit a competitive but pleasant sound that can distract you from head noise. Some people find that a tinnitus masker may even suppress the head noise for several hours after it is used, but this is not true for all users.

Summary

Prior to any treatment of tinnitus or head noise, it is important that you have a thorough examination and evaluation by your otolaryngologist. An essential part of your treatment will be your understanding of tinnitus and its causes.

© 2004 AAO-HNS/AAO-HNSF

Noise, Ears and Hearing Protection

One in 10 Americans has a hearing loss that affects his or her ability to understand normal speech. Excessive noise exposure is the most common cause of hearing loss.

Can Noise Really Hurt My Ears?
Yes, noise can be dangerous. If it is loud enough and lasts long enough, it can damage your hearing.

The damage caused by noise, called sensorineural hearing loss or nerve deafness, can be caused by several factors other than noise, but noise-induced hearing loss is different in one important way--it can be reduced or prevented altogether.

Can I "Toughen Up" My Ears?
No. If you think you have grown used to a loud noise, it probably has damaged your ears, and there is no treatment--no medicine, no surgery, not even a hearing aid--that completely restores your hearing once it is damaged by noise.

How Does the Ear Work?

The ear has three main parts: the outer, middle, and inner ear. The outer ear (the part you can see) opens into the ear canal. The eardrum separates the ear canal from the middle ear. Small bones in the middle ear help transfer sound to the inner ear. The inner ear contains the auditory (hearing) nerve, which leads to the brain.

Any source of sound sends vibrations or sound waves into the air. These funnel through the ear opening, down the ear canal, and strike your eardrum, causing it to vibrate. The vibrations are passed to the small bones of the middle ear, which transmit them to the hearing nerve in the inner ear. Here, the vibrations become nerve impulses and go directly to the brain, which interprets the impulses as sound: music, a slamming door, a voice, etc.

When noise is too loud, it begins to kill the nerve endings in the inner ear. As the exposure time to loud noise increases, more and more nerve endings are destroyed. As the number of nerve endings decreases, so does your hearing. There is no way to restore life to dead nerve endings; the damage is permanent.

How Can I Tell If a Noise Is Dangerous?
People differ in their sensitivity to noise. As a general rule, noise may damage your hearing if you have to shout over background noise to make yourself heard, the noise hurts your ears, it makes your ears ring, or you have difficulty hearing for several hours after exposure to the noise.

Sound can be measured scientifically in two ways. Intensity, or loudness of sound, is measured in decibels. Pitch is measured in frequency of sound vibrations per second. A low pitch, such as a deep voice or a tuba, makes fewer vibrations per second than a high voice or violin.

What Does Frequency of Sound Vibration Have to Do with Hearing Loss?
Frequency is measured in cycles per second, or Hertz (Hz). The higher the pitch of the sound, the higher the frequency.

Young children, who generally have the best hearing, can often distinguish sounds from about 20 Hz, such as the lowest note on a large pipe organ, to 20,000 Hz, such as the high shrill of a dog whistle that many people are unable to hear.

Human speech, which ranges from 300 to 4,000 Hz, sounds louder to most people than noises at very high or very low frequencies. When hearing impairment begins, the high frequencies are usually lost first, which is why people with hearing loss often have difficulty hearing the high pitched voices of women and children. Loss of high frequency hearing also can distort sound, so that speech is difficult to understand even though it can be heard. People with hearing loss often have difficulty detecting differences between certain words that sound alike, especially words that contain S, F, SH, CH, H, or soft C sounds, because the sound of these consonants is in a much higher frequency range than vowels and other consonants.

What about Decibels?
Intensity of sound is measured in decibels (dB). The scale runs from the faintest sound the human ear can detect, which is labeled 0 dB, to over 180 dB, the noise at a rocket pad during launch.

Decibels are measured logarithmically. This means that as decibel intensity increases by units of 10, each increase is 10 times the lower figure. Thus, 20 decibels is 10 times the intensity of 10 decibels, and 30 decibels is 100 times as intense as 10 decibels.

Approx. Decibel Level Example

0 - Faintest sound heard by human ear.

30 - Whisper, quiet library.

60 - Normal conversation, sewing machine, typewriter.

90 - Lawnmower, shop tools, truck traffic; 8 hours per day is the maximum exposure to protect 90% of people.

100 - Chainsaw, pneumatic drill, snowmobile; 2 hours per day is the maximum exposure without protection.

115 - Sandblasting, loud rock concert, auto horn; 15 minutes per day is the maximum exposure without protection.

140 - Gun muzzle blast, jet engine; noise causes pain and even brief exposure injures unprotected ears. Maximum allowed noise with hearing protectors.

How High Can the Decibels Go without Affecting My Hearing?

Many experts agree that continual exposure to more than 85 decibels is dangerous.

Does the Length of Time I Hear a Noise Have Anything to Do with the Danger to My Hearing?
It certainly does. The longer you are exposed to a loud noise, the more damaging it may be. Also, the closer you are to the source of intense noise, the more damaging it is.

Every gunshot produces a noise that could damage the ears of anyone in close hearing range. Large bore guns and artillery is the worse because they are the loudest. But even cap guns and firecrackers can damage your hearing if the explosion is close to your ear. Anyone who uses firearms without some form of ear protection risks hearing loss.

Recent studies show an alarming increase in hearing loss in youngsters. Evidence suggests that loud rock music along with increased use of portable radios with earphones may be responsible for this phenomenon.

Can Noise Affect More Than My Hearing?
A ringing in the ears, called tinnitus, commonly occurs after noise exposure, and it often becomes permanent. Some people react to loud noise with anxiety and irritability, an increase in pulse rate and blood pressure, or an increase in stomach acid. Very loud noise can reduce efficiency in performing difficult tasks by diverting attention from the job.

Who Should Wear Hearing Projectors?
If you must work in an excessively noisy environment, you should wear protectors. You should also wear them when using power tools, noisy yard equipment, or firearms, or riding a motorcycle or snowmobile.

What Are the Laws for on-the-Job Exposure?
Habitual exposure to noise above 85 dB will cause a gradual hearing loss in a significant number of individuals, and louder noises will accelerate this damage.
For unprotected ears, the allowed exposure time decreases by one-half for each 5 dB increase in the average noise level. For instance, exposure is limited to 8 hours at 90 dB, 4 hours at 95 dB, and 2 hours at 100 dB.
The highest permissible noise exposure for the unprotected ear is 115 dB for 15 minutes/day. Any noise above 140 dB is not permitted.
The Occupational Safety and Health Administration, in its Hearing Conservation Amendment of 1983, requires hearing conservation programs in noisy work places. This includes a yearly hearing test for the approximately five million workers exposed to an average of 85 dB or more of noise during an 8-hour work day.

Ideally, noisy machinery and work places should be engineered to be more quiet or the worker's time in the noise should be reduced; however, the cost of these actions is often prohibitive. As an alternative, individual hearing protectors are required when noise averages more than 90 dB during an 8-hour day.

When noise measurements indicate that hearing protectors are needed, the employer must offer at least one type of earplug and one type of earmuff without cost to employees. If the yearly hearing tests reveal hearing loss of 10 dB or more in higher pitches in either ear, the worker must be informed and must wear hearing protectors when noise averages more than 85 dB for an 8-hour day.

Larger losses of hearing and/or the possibility of ear disease should result in referral to an ear, nose and throat physician (otolaryngologist).

What Are Hearing Protectors? How Effective Are They?
Hearing protection devices decrease the intensity of sound that reaches the eardrum. They come in two forms: earplugs and earmuffs.

Earplugs are small inserts that fit into the outer ear canal. They must be snugly sealed so the entire circumference of the ear canal is blocked. An improperly fitted, dirty or worn-out plug may not seal and can irritate the ear canal. They are available in a variety of shapes and sizes to fit individual ear canals and can be custom made. For people who have trouble keeping them in their ears, they can be fitted to a headband.

Earmuffs fit over the entire outer ear to form an air seal so the entire circumference of the ear canal is blocked, and they are held in place by an adjustable band. Earmuffs will not seal around eyeglasses or long hair, and the adjustable headband tension must be sufficient to hold earmuffs firmly around the ear.

Properly fitted earplugs or muffs reduce noise 15 to 30 dB. The better earplugs and muffs are approximately equal in sound reductions, although earplugs are better for low frequency noise and earmuffs for high frequency noise.

Simultaneous use of earplugs and muffs usually adds 10 to 15dB more protection than either used alone. Combined use should be considered when noise exceeds 105 dB.

Why Can't I just Stuff My Ears with Cotton?
Ordinary cotton balls or tissue paper wads stuffed into the ear canals are very poor protectors; they reduce noise only by approximately 7 dB.

What Are the Common Problems of Hearing Protectors?
Studies have shown that one-half of the workers wearing hearing protectors receive one-half or less of the noise reduction potential of their protectors because these devices are not worn continuously while in noise or because they do not fit properly.

A hearing protector that gives an average of 30 dB of noise reduction if worn continuously during an 8-hour work day becomes equivalent to only 9 dB of protection if taken off for one hour in the noise. This is because decibels are measured on a logarithmic scale, and there is a 10-fold increase in noise energy for each 10 dB increase.

During the hour with unprotected ears, the worker is exposed to 1,000 times more sound energy than if earplugs or muffs had been worn.

In addition, noise exposure is cumulative. So the noise at home or at play must be counted in the total exposure during any one day. A maximum allowable while on-the-job followed by exposure to a noisy lawnmower or loud music will definitely exceed the safe daily limit.

Even if earplugs and/or muffs are worn continuously while in noise, they do little good if there is an incomplete air seal between the hearing protector and the skin.

When using hearing protectors, you will hear your own voice as louder and deeper. This is a useful sign that the hearing protectors are properly positioned.

Can I Hear Other People and Machine Problems If I Wear Hearing Protectors?
Just as sunglasses help vision in very bright light, so do hearing protectors enhance speech understanding in very noisy places. Even in a quiet setting, a normal-hearing person wearing hearing protectors should be able to understand a regular conversation.

Hearing protectors do slightly reduce the ability of those with damaged hearing or poor comprehension of language to understand normal conversation. However, it is essential that persons with impaired hearing wear earplugs or muffs to prevent further inner ear damage.

It has been argued that hearing protectors might REDUCE a worker's ability to hear the noises that signify an improperly functioning machine. However, most workers readily adjust to the quieter sounds and can still detect such problems.

What If My Hearing Is Already Damaged? How Can I Tell?
Hearing loss usually develops over a period of several years. Since it is painless and gradual, you might not notice it. What you might notice is a ringing or other sound in your ear (called tinnitus), which could be the result of long-term exposure to noise that has damaged the hearing nerve. Or, you may have trouble understanding what people say; they may seem to be mumbling, especially when you are in a noisy place such as in a crowd or at a party. This could be the beginning of high-frequency hearing loss; a hearing test will detect it.

If you have any of these symptoms, you may have nothing more serious than impacted wax or an ear infection, which might be simply corrected. However, it might be hearing loss from noise. In any case, take no chances with noise-the hearing loss it causes is permanent. If you suspect a hearing loss, consult a physician with special training in ear care and hearing disorders (called an otolaryngologist or otologist). This doctor can diagnose your hearing problem and recommend the best way to manage it.

© 2004 AAO-HNS/AAO-HNSF

Hearing Loss

Nearly 30 million Americans have impaired hearing. The most common cause of hearing loss in children is otitis media. For the elderly-the largest group affected-excessive noise, drugs, toxins, and heredity are the most frequent contributing factors.

Hearing loss is a medical disorder. In a limited number of patients, it can be surgically corrected; medical devices and rehabilitation can substantially reduce hearing loss in the vast majority of patients who cannot be helped by surgery. The medical specialists who diagnose and treat hearing disorders are called otolaryngologists-head and neck surgeons, or more commonly, "ear, nose and throat doctors."

HEARING LOSS

The first step toward better hearing is an examination by your physician and a hearing test by a qualified hearing professional. In many cases, hearing loss is caused by a simple blockage in the ear canal. In other instances, medication or surgery could improve hearing ability. For others, hearing aids or other listening devices would be beneficial. A physician who specializes in ear problems is the best judge of how to evaluate and treat such disorders. An audiologist is the hearing health specialist who works with the medical doctor to provide diagnostic and rehabilitative services for hearing loss.

Does my baby have hearing loss?

If your newborn child:

• Does not startle, move, cry or react in any way to unexpected loud noises,
• Does not awaken to loud noises,
• Does not turn his/her head in the direction of your voice, or
• Does not freely imitate sound,

He or she may have some degree of hearing loss.

More than three million American children have a hearing loss. An estimated 1.3 million of these children are under three years of age. Parents and grandparents are usually the first to discover hearing loss in a baby, because they spend the most time with them. If at any time you suspect your baby has a hearing loss, discuss it with your doctor. He or she may recommend evaluation by an otolaryngologist-head and neck surgeon (ear, nose and throat specialist).

Hearing loss can be temporary, caused by earwax or middle ear infections. Many children with temporary hearing loss can have their hearing restored through medical treatment or minor surgery.

However, some children have sensorineural hearing loss (sometimes called nerve deafness), which is permanent. Most of these children have some usable hearing, and children as young as three months of age can be fitted with hearing aids. Early diagnosis, early fitting of hearing or other prosthetic aids, and an early start on special education programs can help maximize a child's existing hearing. This means your child will get a head start on speech and language development.