Frequently Asked Questions

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How long does it take for damage to hearing to manifest itself?

Damage can be apparent immediately, or it can gradually become noticeable. Because the majority of hearing impairment comes on gradually, this makes it more difficult to notice that damage has taken place.

Where does ear wax come from, and what does it have to do with hearing?

Wax in the ears is a common and easily treatable cause of deafness, discomfort, and sometimes noises in your ears (tinnitus). Ear wax is produced by all of us. It only causes problems when it builds up, which may be due to over-production or difficulties in the natural clearance of the wax.


You may notice a build-up of wax by:

  • having increasing difficulty hearing
  • pain in your ear or ears
  • hearing a noise or ringing in your ears (tinnitus)
  • an awareness of something blocking your ears
  • temporary deafness after swimming or having a bath or shower


The skin cells lining our outer ear canals include tiny glands, similar to sweat glands, which produce wax. The point seems to be that this acts as a protective layer, which traps dust and other particles which get into the ear. The wax slowly works its way to the outside, taking the trapped dirt and dust with it.

Most people’s ears clear the wax, which probably comes off on our pillows and towels etc., at a rate which means that it does not build up. Some people may, at some stages in their lives produce wax at a faster rate. Other people have ear canals that are narrow, or that are at an angle which slows the natural passage of the wax. In these people the wax builds up.

The wax may eventually block off the ear canal all together. If this happens, hearing is reduced, and there is an increased likelihood that stagnation may lead to an infection building up behind the obstruction.


The doctor or nurse will look in your ears. We all produce wax, so what they are looking for is evidence of the wax actually blocking off the ear canal.

Deafness can be caused by other problems in the ear, and if there is not enough wax to explain your problem, the doctor will be able to discuss other possible causes for your symptoms, such as fluid collecting on the other side of the ear drum when the tube which drains from the middle ear to the throat (the eustachian tube) has become blocked, as happens after a cold.


If you think you have ear wax blocking your ears, either buy some wax softening drops from the pharmacy, or put a couple of drops of warmed (body temperature) olive oil into your ear two or three times a day, for a few days.

If this does not solve the problem after three or four days, arrange to see someone regarding having your ears washed out. The nurse at your doctor’s office will usually be able to do this for you.

If you have ear pain, a temperature, or are otherwise concerned, you should speak to or see your doctor sooner than above.

If you know that you have a hole in your ear drum (a perforation), you should not put drops in your ear without having first discussed it with your doctor or a competent medical advisor.

(The above information is from

What sounds cause noise-induced hearing loss (NIHL)?

  • 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, usual 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 small arms fire, all emitting sounds from 120 decibels to 140 decibels. Sounds of less than 75 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 and to the nerve of hearing. These structures can be injured by noise in two different ways: from an intense brief impulse, such as an explosion, or from continuous exposure to noise, such as that in a woodworking shop.

What are the effects of noise-induced hearing loss?

  • The effect from sound can be instantaneous and can result in an 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 (an experience of sound like 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 intermittently throughout a lifetime.
  • The damage that occurs slowly over years of exposure to loud noise is accompanied by various changes in the structure of the hair cells. It also results 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 within 16 hours after exposure to loud noise.
  • Hearing that does not recover is because permanent damage has occurred. This hearing loss is permanent.
  • Both forms of NIHL can be prevented by the regular use of hearing protectors such as ear plugs or ear muffs.

What are the symptoms of NIHL?

The symptoms of NIHL that occur over a period of continuous exposure increase gradually. 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 with a hearing test.

Who is affected by NIHL?

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 work place, in recreational settings and at home. There is an increasing awareness of the harmful noises in recreational activities, for example, target shooting or hunting, snowmobiles, go-carts, woodworking and other hobby equipment, power horns, cap guns and model airplanes. Harmful noises at home may come from vacuum cleaners, garbage disposals, lawn mowers, leaf blowers and shop tools. People who live in either urban or rural settings may be exposed to noisy devices on a daily basis. Of the 28 million Americans who have some degree of hearing loss, about one-third have been affected, at least in part, by noise.

Can NIHL be prevented?

Noise-induced hearing loss is preventable. All individuals should understand the hazards of noise and how to practice good health in everyday life.

  • Know which noises can cause damage (those above 85 decibels).
  • Wear ear plugs or other hearing protective devices when involved in a loud activity (special earplugs and ear muffs are available at hardware stores and sporting good stores).
  • Be alert to hazardous noise in the environment.
  • Protect children who are too young to protect themselves.
  • Make family, friends and colleagues aware of the hazards of noise.
  • Have a medical examination by an otolaryngologist, a physician who specializes in diseases of the ears, nose, throat, head and neck, and a hearing test by an audiologist, a health professional trained to identify and measure hearing loss and to rehabilitate persons with hearing impairments.

What research is being done for NIHL?

Scientists focusing their research on the mechanisms causing NIHL hope to understand more fully the internal workings of the ear, that will result in better prevention and treatment strategies. For example, scientists have discovered that damage to the structure of the hair bundle of the hair cell is related to temporary and permanent loss of hearing. They have found that when the hair bundle is exposed to prolonged periods of damaging sound, the basic structure of the hair bundle is destroyed and the important connections among hair cells are disrupted which directly lead to hearing loss.

Other studies are investigating potential drug therapies that may provide insight into the mechanisms of NIHL. For example, scientists studying altered blood flow in the cochlea are seeking the effect on the hair cells. They have shown reduced cochlear blood flow following exposure to noise. Further research has shown that a drug that promotes blood flow used for treatment of peripheral vascular disease (any abnormal condition in blood vessels outside the heart), maintains circulation in the cochlea during exposure to noise. These findings may lead to the development of treatment strategies to reduce NIHL.

Continuing efforts will provide opportunities that can aid research on noise-induced hearing loss as well as other diseases and disorders that cause hearing loss. Research is the way to develop new, more effective methods to prevent, diagnose, treat and eventually eliminate these diseases and disorders and improve the health and quality of life for all Americans.

(The above information is from Wise Ears – NID CD 2001.)

At what age would it be okay to bring a child (infant, toddler, preschool or school age) to a Drag Car racetrack? How long of an exposure (without ear protection) to the noise at a Drag Car racetrack would potentially cause problems- 1 hour, 2 hours, for a 1 year old?

These are good questions! All of us start out life with a full set of tiny sensors in the inner ear called “hair cells”. They are so small that they can only be seen with a very high powered microscope. The hair cells are spread across a long membrane in the cochlea (inner ear) like the keys on a piano… low frequencies at one end and high frequencies at the other. We all start losing hair cells from the time we are born. They tend to die from the high frequency end first. This progresses very slowly throughout our lives and becomes noticeable in our late 50′s and early 60′s in most people.

One thing that seems to speed up that process is exposure to loud noise. Loud bursts of noise (like a dragster blasting off from the starting line) or prolonged noise (like working in a moderately noisy factory for years) can have the exact same effect. There is no evidence that a child will be more or less vulnerable to noise exposure than an adult. The fact is that BOTH are going to get damage from loud sounds. The only thing is that a toddler has more to lose because they are so much earlier on in the natural process of losing hair cells.

I’d recommend that you get a pair of ear muffs for yourself and for the child. Toddler’s heads are almost adult size by the time they are a year old, so most ear muffs will work fine. Just pop them on when you anticipate a blast of sound and take them off when you don’t. This will reduce the total cumulative noise exposure and protect those thousands of little hair cells. It will also set a good example for the child and for the other people attending the race. They can learn that you can have a great time at the races and yet protect your important hearing at the same time.

Other important websites: and

I am looking for guidelines for selecting ear protection for a teenager with a pre-existing high frequency SNHL. What is an appropriate NRR rating? This is a teenager who hunts with his father. He is also concerned with being able to hear his father speak during this activity.

He’s right. Hunting requires listening and protection during the same exercise. He not only needs to hear his father, he probably wants to listen to the surrounding sounds. He needs good hearing function with “on-demand” maximum protection. Regular old ear plugs will probably give him reasonable protection but not give him enough functional hearing. Musician’s ear plugs would give him his choice of how much attenuation he would like (so he could communicate) but the protection would be inadequate for gunfire. There is a third option developed especially for hunting. Electronic hearing ear muff type protectors allow the user to hear low-moderate level sounds, but are protected from dangerous levels by sound triggered attenuation circuits. Some systems provide increased attenuation as sound levels increase.

Here are some suggested websites.

What about sounds outside our hearing range: Is there any damage – dog whistles, etc?

Damage to hearing is caused by sounds that are too loud, regardless of their frequency. Damage from sound is determined by the loudness of the sound and also by the duration of exposure to the sound. Brief exposure to an 85 dB sound (such as a blender) is O.K. However, prolonged continuous exposure (8 or more hours) to the same sound could damage hearing. Some sounds (such as gunfire or standing next to a helicopter) are so loud (120-160 dB), that any brief exposure to them without wearing earmuffs or earplugs can damage hearing. (This means that the dog whistles are at a very high frequency but that they do not move the air enough to damage the inner ear hair cells.)

How/who originated decibels?

Read about the history of bels and decibels (a decibel is one-tenth of a bel):

(The above information is from

Is it only the decibel level that is important in terms of damage to the ears, or does the frequency of the sound matter as well? In other words are high or low frequencies more dangerous than those in the middle range?

The decibel level and time of exposure are the most important considerations. Some sounds — such as gunfire, explosions, etc. — are so loud (140 or more decibels), ANY brief exposure to them at close range can cause permanent damage and hearing loss. Sounds at 100 decibels (such as loud music through stereo headphones) will take a while longer (1-2 hours of exposure) to cause permanent damage to hair cells in the cochlea. The frequency of the sound is less important than its decibel level and time of exposure.

I have a college campus that is now at the end of a new runway. The jets take off directly over a college campus – about 200-300 feet over the campus. What are the limitations and or OSHA limitations etc for something like this?

This is not an OSHA issue. It is a community noise issue and those ordinances vary from community to community. The FAA might also be involved. I suggest you visit the Noise Pollution Clearinghouse at or contact Les D. Blomberg Executive Director Noise Pollution Clearinghouse (NPC) PO Box 1137 Montepelier, VT 05601-1137 (802) 229-1659 – Office for assistance and informations on ordinances.

(The above information is from National Heaaring Conservation Association

MP3 – Are they safe for children of all ages?

They are safe for all ages as long as they are not too loud for too long.

MP3 – Is there any info that indicates how loud these devices actually are?

Generally MP3 players including iPods can be turned up to a maximum of around 103 dB using standard iPod earphones.

MP3 – Does loudness vary a great deal from one brand/model to another?

The output levels across brands of models tests are about the same, especially in the high decibel level – Max 103dB. Only iPod has volume limited software.

MP3 – What about the headset, over the ear vs. ear buds; one less damaging than the other?

No – it depends on how loud you set the volume and for how long you listen to that volume. At the 2006 Noise-Induced Hearing Loss in Children at Work and at Play Conference There were several papers that addressed this issue. Fligor and T. Ives – Does Earphone Type Affect Risk for Recreational Noise-induced Hearing Loss? Portnuff and B. Fligor – Sound Output Levels of the iPod and Other MP3 Players: Is There Potential Risk to Hearing?

(The above information is from

MP3 – How loud is too loud when the volume wheel tells me nothing?

A rule of thumb is if you can not understand someone talking to you in a normal speaking voice when they are an arm’s length away… it is too loud. This rule works with standard earbuds and headphone. If you are using noise-canceling headphone, see the following rule of thumb.

MP3 – Is there a rule of thumb about setting limits on the volume wheel?

No more than 90 minutes at the 80% volume.

MP3 – If my child is going to crank his music now and then is it less damaging to listen to it thru speakers rather than a personal headset?

It is the decibel level that reaches the ears and how long it is listened to that are the issues. No matter what the sound source is, if that sound is 85dB or more, there are limits to how long a person (any person) can safely listen to it.