What is the importance of noise-induced hearing loss?

The industrial and technological revolution may have propelled society to higher levels of achievement, but this progress has also made the world a noisier place in which to live. In fact, noise pollution is a growing health hazard and can be found almost everywhere. Car alarms, leaf blowers, gunshots, boom boxes, and traffic congestion fill our cities with decibels (the measure of sound intensity). Escaping to the country may not provide a quiet refuge, and even farmers are at high risk for exposure to noise from their farm machinery.
Unpleasant or unwanted sounds are not the only harmful noises to which we may be exposed. For example, the music at a concert and the pounding of a jackhammer on the street can be equally damaging to the inner ear. Loud sounds (acoustic energies) delivered with equal intensity or over extended periods of time, regardless of their source, are equally dangerous. Eventually, continued or repeated exposures to high intensity sound can cause acoustic trauma to the ear. This trauma can result in hearing loss, ringing in the ears (tinnitus), and occasional dizziness (vertigo), as well as non-auditory effects, such as increases in heart rate and blood pressure.
One-third of the 30 million Americans with hearing loss have an impairment that is at least partially attributed to excessive noise exposure. Noise remains the most common preventable cause of irreversible sensorineural (involving the ear's sensory nerve) hearing loss.
What are acoustic trauma and noise-induced hearing loss?
Acoustic trauma occurs when any excessive sound energy strikes the inner ear. If it is brief, the noise may cause a reversible, temporary hearing loss, technically known as a temporary threshold shift. For example, after a loud rock concert, it is common to experience hearing dullness and ringing in the ears for several hours. In this situation, if symptoms persist beyond several days, oral steroids (cortisone-type medications) may help the inner ear to recover. If the noise is loud enough and the duration of exposure long enough, however, it may cause a permanent threshold shift. This condition is called noise-induced hearing loss, which has no cure and is irreversible.
Sudden hearing loss produced by a sudden and very loud noise (blast injury) is called acute acoustic trauma. If the sound is loud enough, it can cause the eardrum to rupture or the person to have a complete loss of hearing. Sometimes, particularly if the sudden loss is total and occurs combined with dizziness, immediate surgical exploration of the ear may be necessary. In this circumstance, the ear surgeon may need to locate and patch a hole (perilymphatic fistula) between the inner ear fluid space and the middle ear space.
How can a person tell if a noisy situation is dangerous to their hearing?
People may differ in their sensitivity to noise. Nevertheless, as a general rule, noise is probably damaging to the hearing if the noise:
- makes it necessary to shout to be heard over the background noise,
- causes ear pain,
- makes the ears ring, or
- causes a loss of hearing for several hours or more after exposure to the noise.
In contrast to popular belief, there is no truth to the idea that a person is able to "toughen up" the ears by frequent exposure to loud noise. In reality, cumulative noise in the past has probably damaged the ears to such a degree that a person doesn't hear the noise as much. Unfortunately, limited treatment is available for noise-induced hearing loss once the damage has occurred.

QUESTION
What is hearing loss? See AnswerHow loud can a sound get before it affects hearing?
Many experts agree that continual exposure to more than 85 decibels (dB) is dangerous to the ears. As already mentioned, the decibel is a measure of the intensity of sound. For example:
- the faintest sound the human ear can detect is labeled 0 dB, whereas the noise at a rocket pad during launch approaches 180 dB;
- a quiet whisper is approximately 30 dB;
- normal conversation is 60 dB;
- a lawnmower is 90 dB; and
- the sound from an iPod Shuffle has been measured at 115 dBs.
Decibels are measured logarithmically, which means that the sound energy of noise increases by units of 10. Therefore, a dB increase of a sound from 20to 30 dB is an increase of 10 times, and a dB increase of a sound from 20 to 40 dB corresponds to increase of 100 times (10 times 10).
Do the duration and closeness of exposure to loud noise relate to hearing damage?
There is a direct correlation between the duration of exposure to a loud noise and the damage to hearing. This means that the longer the exposure, the greater the damage. Furthermore, the closer one is to the source of the intense noise, the more damaging it is. An example of this is iPod hearing loss. There is an alarming increase in hearing loss in children and young adults due to listening to loud music through earplugs so close to the eardrum.
Another example is discharging firearms. The loud blast of a gun so close to the ear can cause problems for anyone not wearing ear protection.
What factors increase a person's susceptibility to noise-induced hearing loss?
The following factors have been associated with an increased susceptibility to noise-induced hearing loss:
- blue eyes,
- light skin,
- family history of hearing loss,
- diabetes mellitus,
- Meniere disease,
- iron deficiency,
- vitamin A deficiency,
- older age,
- atherosclerosis (hardening of the arteries), and
- smoking tobacco.
Health News
- Most Injection Drug Users Are Not Seeking Out Fentanyl: Study
- Cancer Survivors Who Keep Smoking Have Double the Risk for Heart-Related Death
- Canada to Become 1st Country to Mandate Warning Labels on Individual Cigarettes
- Nova Scotia Wildfires Sending Unhealthy 'Smoke Plume' to U.S. Northeast
- U.S. Teen Birth Rate Hits Another Historic Low
More Health News »
How else can noise affect a person?
After exposure to noise, tinnitus, which is a ringing or another sound in the ears, occurs commonly. The tinnitus is a sign that inner ear damage or nerve destruction has occurred. Initially the tinnitus is temporary, lasting only several hours. As more cumulative exposure and damage occur, the tinnitus will last longer until it eventually becomes permanent. Loud noise will also cause some people to have anxiety and irritability, an increase in heart rate and blood pressure, or an increase in stomach acid. In addition, very loud noise can reduce efficiency in performing difficult tasks by diverting attention from the job.
What are the regulations regarding on-the-job exposure to noise?
Habitual exposure to noise above 85dB will cause a gradual hearing loss in a significant number of individuals. Moreover, noise greater than 85dB will accelerate this damage. Accordingly, the U.S. Occupational Safety and Health Administration (OSHA) has imposed regulations nationwide regarding on-the-job exposure to noise. 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 hr at 95 dB, and 2 hr at 100 dB. The highest permissible noise exposure for the unprotected ear is 115 dB for 15 minutes per day. Any noise above 140 dB is not permitted.
OSHA, in its Hearing Conservation Amendment of 1983, required the institution of a hearing conservation program in noisy workplaces. Such a program must include a yearly hearing test for workers exposed to an average of 85 dB or more of noise during their 8-hour workday. It turns out that approximately 25% of the American industrial workforce is exposed to this level of noise.
Ideally, noisy machinery and work places should be designed to be quieter, and/or the workers' time in the noise should be reduced. The cost of reducing noise exposure in these ways, however, 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 test reveals a hearing loss of 10 dB or more in the higher sound frequencies (pitch) in either ear, the worker must be informed. (The higher frequencies of sound are the most sensitive to noise damage.) Also, the worker must wear hearing protectors when noise averages more than 85 dB for an 8-hour day. Greater losses of hearing or the possibility of ear disease necessitates referral to an ear doctor (otolaryngologist).
How effective are hearing protection devices?
Hearing protection devices decrease the intensity of sound that reaches the eardrum. They come in two forms: earplugs and earmuffs. Earplugs: Earplugs are small inserts that fit into the outer ear canal. To be effective they must totally block the ear canal with an air-tight seal. 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: Earmuffs fit over the entire outer ear to form an air seal. They are held in place by an adjustable band. Earmuffs must be snugly sealed so the entire circumference of the ear canal is blocked.
Properly fitted earplugs or muffs reduce noise by 15 to 30 dB of sound. The better earplugs and earmuffs are approximately equally effective in sound reduction. However, earplugs are better protection against low frequency noise (such as noise from a jackhammer), and earmuffs are better protection against high frequency noise (such as noise from an airplane taking off). For high frequency sounds, think of the high-pitched treble keys of the piano, whereas for low frequency sounds, think of the low- or deep-pitched bass keys of the piano.
Simultaneous use of earplugs and muffs usually adds 10 to 15 dB more protection than either used alone. Combined use should be considered when the noise exceeds 105 dB. It is important to understand that ordinary cotton balls or tissue paper wads stuffed into the ear canals are very poor protectors since they only reduce noise by approximately 7 dB.
Excessive noise exposure may occur at live rock concerts as well as in more intimate venues for music whenever amplification is utilized. The damage to hearing from music is every bit as permanent as that incurred by other means. As a matter of fact, special high-fidelity earplugs have been developed specifically for such situations and are being utilized by musicians and professional sound engineers. These earplugs are specially designed to eliminate the so-called plugged (occluded) ear effect and to maintain an even reduction of sound across the frequency range. Otherwise, when the ear is plugged, the plugged ear effect makes one's voice sound more bass, or deeper, and louder. Try it by occluding your ear(s) (gently) with your finger, and speak. You'll hear the plugged ear effect.
Subscribe to MedicineNet's General Health Newsletter
By clicking Submit, I agree to the MedicineNet's Terms & Conditions & Privacy Policy and understand that I may opt out of MedicineNet's subscriptions at any time.
What are the common problems with hearing protectors?
Studies have shown that one-half of the workers wearing hearing protectors receive only one-half or less of the noise reduction potential of their protectors. This diminished protection occurs because these devices either are not worn continuously while exposed to noise or they do not fit properly.
As previously mentioned, a hearing protector can give an average of 30 dB noise reduction if worn continuously during an 8-hour workday. If taken off for just one hour while exposed to noise, however, such a protector would provide only an average of 9 dB of protection during the 8 hours. This substantial reduction in protection occurs because with the logarithmic scale used to measure decibels, a 10-times increase in noise energy occurs for each 10 dB increase in sound. Thus, 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. (For the 30 dB, 10 x 10 x 10 = 1000 times more noise.)
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 on-the-job exposure followed by further exposure at home to a noisy lawnmower or loud music will definitely exceed the safe daily limit.
Even if earplugs and/or earmuffs are worn continuously while exposed to noise, they do little good if there is an incomplete air seal between the hearing protector and the skin. As mentioned above, when using ordinary hearing protectors, it is common to hear one's voice as louder and deeper. This plugged ear effect can actually be taken as a useful sign that the hearing protectors are properly positioned.
Do hearing protectors prevent a person from communicating with others?
The answer is no, at least for people with normal hearing. In fact, just as sunglasses help vision in very bright light, 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. Nevertheless, it is essential that persons with impaired hearing wear earplugs or earmuffs to prevent further inner ear damage from noise.
It has been argued that hearing protectors might reduce a worker's ability to hear the noises that signify an improperly functioning machine. Most workers, however, readily adjust to the quieter sounds and can still detect such problems.
From 
Healthy Resources
Featured Centers
Health Solutions From Our Sponsors
How do medical professionals identify hearing loss?
Hearing loss usually develops over a period of several years. Since the hearing loss is painless and gradual, many people may not notice it. What someone may notice is tinnitus, which is a ringing or another sound in the ear. The tinnitus could be the result of long-term exposure to noise that has damaged the hearing nerve. A person may have trouble understanding what people are saying or may hear everyone as mumbling. Such hearing difficulties are especially apt to occur when one is trying to hear in a noisy place such as in crowd or at a party. These difficulties could be the beginning of high-frequency hearing loss.
A typical hearing test (audiogram) of a person with noise induced hearing loss will initially show only a high frequency loss at 4000 Hz. (Hertz or Hz is the measure of sound frequency or pitch. Four thousand Hz is high frequency, while 250 or 500 Hz would be low frequency). With continued noise exposure and hearing loss, the audiogram will show a broader loss to include lower (deeper)frequencies.
Noise-induced hearing loss will almost always affect both ears equally, but in some situations, especially with firearm usage, it may be worse in one ear than in the other. For example, firing a rifle tends to injure the ear opposite the side of the trigger finger due to the shadow (blocking the sound) effect of the shooter's head.
What can be done to treat hearing loss?
If a person has any of these symptoms that suggest hearing loss, he or she should consult a physician with special training in ear and hearing disorders (an otolaryngologist or otologist). This type of doctor can diagnose hearing problems and recommend the best way to manage them.
While there is no cure for noise-induced hearing loss, there is some promising research being done. The National Institute on Deafness and Other Communication Disorders (NIDCD) is looking at the use of antioxidants to prevent hearing loss and restore hearing. NIDCD-funded researchers have shown that aspirin and vitamin E can reduce hearing loss if used before exposure to loud noise.
Researchers at the University of Michigan used vitamins A, C, E and magnesium prior to loud noise exposure to prevent hearing loss in animal studies. Studies on people are in progress.
For examples of sounds measured in dBs, The American Academy of Otolaryngology-Head and Neck Surgery provides an Interactive Loudness Scale.
Health Solutions From Our Sponsors
REFERENCE:
"Noise-Induced Hearing Loss." National Institute of Deafness and Other Communication Disorders. May 15, 2015.
Top Noise Induced Hearing Loss and Its Prevention Related Articles
Anemia
Anemia is the condition of having less than the normal number of red blood cells or less than the normal quantity of hemoglobin in the blood. The oxygen-carrying capacity of the blood is, therefore, decreased. There are several types of anemia such as iron deficiency anemia (the most common type), sickle cell anemia, vitamin B12 anemia, pernicious anemia, and aplastic anemia. Symptoms of anemia may include fatigue, malaise, hair loss, palpitations, menstruation, and medications. Treatment for anemia includes treating the underlying cause for the condition. Iron supplements, vitamin B12 injections, and certain medications may also be necessary.Detecting Hearing Loss in Children
There are many degrees of hearing, from normal hearing to deafness. Many states mandate the testing of newborns before leaving the hospital. The risk factors for hearing loss in children include- a family history of hearing loss,
- frequent ear infections,
- diagnosis of a learning disability,
- syndromes associated with hearing loss,
- speech delay, and
- infectious diseases that cause hearing loss.
- the child not responding to his or her name,
- the child asking for words to be repeated, and
- the child not paying attention to what is being said.
Diabetes (Type 1 and Type 2)
Diabetes is a chronic condition characterized by high levels of sugar (glucose) in the blood. The two types of diabetes are referred to as type 1 (insulin dependent) and type 2 (non-insulin dependent). Symptoms of diabetes include increased urine output, thirst, hunger, and fatigue. Treatment of diabetes depends on the type.Dizziness
Dizziness is a symptom that often applies to a variety of sensations including lightheadedness and vertigo. Causes of dizziness include low blood pressure, heart problems, anemia, dehydration, and other medical conditions. Treatment of dizziness depends on the cause.Middle Ear Infection (Otitis Media)
A middle ear infection (otitis media) can cause earache, temporary hearing loss, and pus drainage from the ear. It is most common in babies, toddlers, and young children. Learn about causes and treatment.Ear Tubes
When a child has repeated middle ear infections or fluid build-up in the ears, which causes problems with speech or hearing, surgery to place tubes inside the ear is often recommended. The surgery is called myringotomy. Preparing your child for this procedure will help comfort them, and knowing what to expect before, during, and after surgery is important as well.Hearing Loss: Causes of Hearing Loss
Problems with your ears like ear infections can cause signs of hearing loss. This may be sensorineural hearing loss or conductive hearing loss. Learn how loud noises can induce hearing loss, the signs of hearing loss, and different ways you can prevent hearing problems.Hearing Losss Quiz
Can hearing loss be reversed? Take this quiz to find out!How Do You Clear Blocked Eustachian Tubes?
Learn what medical treatments can help ease your blocked eustachian tube symptoms and speed up your recovery for blocked eustachian tubes. Ear infections are common and usually go away on their own after a few days, even without medical treatment. Learn about causes and treatment.Newborn Infant Hearing Screening
A newborn infant hearing screening is performed before a child is discharged from the hospital. If an infant doesn't pass the test, a rescreen is performed. Detecting hearing loss at an early age increases a child's chance of having a healthy and more productive life. There are two methods of testing hearing in infants: auditory brainstem response (ABR) and otoacoustic emission (OAE). Both tests are accurate, automated, and don't require a visible response from the infant.Tinnitus
Tinnitus is described as a throbbing, ringing, clicking, or buzzing in one or both ears. Tinnitus is caused by trauma to the ear, over exposure to loud noises, medication, and diseases or infections of the ear such as multiple sclerosis, TMJ, autistic neruoma, Meniere's disease, hearing loss, and aging. Treatments include medication, tinnitus masking, retraining therapy, and relief therapy.
Tinnitus Slideshow
What is tinnitus? Explore tinnitus (ringing in the ears) causes, symptoms, relief remedies, treatments and prevention tips. Learn about pulsatile tinnitus.What Can Trigger Vertigo?
Vertigo is the sensation of spinning or rocking, even when someone is at rest. Vertigo may be caused by a problem in the brain or spinal cord or a problem within in the inner ear. Head injuries, certain medications, and female gender are associated with a higher risk of vertigo. Medical history, a physical exam, and sometimes an MRI or CT scan are required to diagnose vertigo. The treatment of vertigo may include medication, special exercises to reposition loose crystals in the inner ear, or exercises designed to help the patient re-establish a sense of equilibrium. Controlling risk factors for stroke (blood pressure, weight, cholesterol, and blood glucose) may decrease the risk of developing vertigo.