Protection For Ears and Hearing, Affected From Noise
Information provided by: American Academy of Otolaryngology
It is A Fact: That excessive noise exposure is the most common cause of hearing loss, and that it affects the ability of one in 10 Americans to understand normal speech.
Is it true that Noise Can Really Hurt My Ears?
Yes - If it is loud enough and lasts long enough, noise can be dangerous as it can damage your hearing. This type of damage caused by noise, is called sensorineural hearing loss or nerve loss, there can several other factors that can cause this loss other than noise, but noise-induced hearing loss is different in one important way - it can be reduced or prevented altogether.
Is there a way that I can "Toughen Up" My Ears?
Unfortunately, No, when you think that you have gotten used to a loud noise, then it probably has already damaged your ears. Once your hearing is damaged by noise, there is no treatment - no medicine, no surgery, not even a hearing aid that truly corrects your hearing.
How Does the Ear Work?
There are three main parts to the ear: The outer, middle, and inner ear. The outer ear which is the part you can see opens into the ear canal. The eardrum separates the ear canal from the middle ear, there are small bones in the middle ear that help transfer sound to the inner ear. It is the inner ear that contains the auditory (hearing) nerve, which then leads to the brain.
Vibrations or sound waves are sent into the ear, by any source of sound. These vibrations funnel through the ear opening, down the ear canal, and strike your eardrum, causing it to vibrate. Then these vibrations are passed to the small bones of the middle ear, which in turn transmit them to the hearing nerve in the inner ear. It is in the inner ear where the vibrations become nerve impulses and go directly to the brain. Then the brain interprets the impulses as sound: music, a slamming door, a voice, etc.
What happens when noise is too loud?
As the exposure time to loud noise increases, it begins to kill the nerve's endings in the inner ear, and as a result more and more nerve endings are destroyed, As the number of nerve endings decreases, so does your hearing. The damage is permanent and there is no way to restore life to dead nerve endings;.
People have different sensitivity to noise. As a general rule, noise may damage your hearing,
(1) If you have to shout over background noise to make yourself heard,
(2) The noise hurts your ears,
(3) It makes your ears ring,
(4) Or you are slightly deaf for several hours after exposure to the noise.
There are two scientific ways that sound can be measured.
1. Intensity, or loudness of sound, is measured in decibels.
2. Pitch is measured in frequency of sound vibrations per second. For example a low pitch such as a deep voice or a tuba makes fewer vibrations per second than a high voice or violin.
How Does Frequency affect 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.
To most people, human speech, which ranges from 300 to 4,000 Hz, sounds louder to than noises at very high or very low frequencies.
At the onset of hearing impairment, it is the high frequencies that are often lost first, which is why people with hearing loss often have difficulty hearing the high pitched voices of women and children.
Distortion of sound can also be a result of loss of high frequency hearing so that speech is difficult to understand even though it can be heard. Hearing impaired people 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 consonant is in a much higher frequency range than vowels and other consonants.
What and How Are Decibels Measured?
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 decibel is 10 times the intensity of 10 decibels, and 30 decibels is 100 times as intense as 10 decibels.
Approximate Decibel Level Examples
Approximate Decibel Level
The quietest sound you can hear
Whisper, quiet library
Normal conversation, sewing machine, typewriter
Lawnmower, shop tools, truck traffic, 8 hours per day is the maximum exposure (protects 90% of people)
Chainsaw, pneumatic drill, snowmobile; 2 hours per day is the maximum exposure without protection
Sandblasting, loud rock concert, auto horn; 15 minutes per day is the maximum exposure without protection.
Gun muzzle blast, jet engine; Noise causes pain and even brief exposure injures unprotected ears. Maximum allowed noise with hearing protector.
How High Can the Decibels Go Without Affecting My Hearing?
Many experts agree that continual exposure to more than 85 decibels may become dangerous.
What about the Length of Time I Hear a Noise Does That Have Anything to with the Danger to My Hearing?
Yes, most certainly. 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. And because they are the loudest, large bore guns and artillery are the worst. 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.
Is There Anything Else That Noise Can Affect Besides My Hearing?
Yes, tinnitus, which is a ringing in the ears, commonly occurs after noise exposure, and it often becomes permanent. And there are some people that react to loud noise with anxiety and irritability, an increase in pulse rate and blood processor, or an increase in stomach acid. And also a continuous very loud noise can reduce efficiency in performing difficult tasks by diverting attention from the job.
Who Should Wear Hearing Protectors?
Anyone who must work in an excessively noisy environment, should wear protectors. You should also wear them when you are using power tools, noisy yard equipment, or firearms.
Are there Any Laws for On-the-Job Exposure?
The Occupational Safety and Health Administration, (OSHA) 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 d5 or snore of noise during an 8-hour work day.
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 hr 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/day. Any noise above 140 dB IS NOT PERMITTED.
In an ideal situation, noisy machinery and work places should be engineered to be more quiet or the worker's time in the noise should be reduced; but because of the cost of these actions it 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 l0 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 They and How Effective Are Hearing Protectors?
What the devices for hearing protection do is decrease the intensity of sound that reaches the eardrum. These devices come in two forms: earplugs and earmuffs.
Earplugs are small inserts that fit into the outer ear canal. For these earplugs to be effective they must totally block the ear canal with an airtight seal. These small inserts are available in a variety of shapes and sizes so they will fit individual ear canals and can also be custom made. They can also be fitted to a headband, for people who have trouble keeping them in their ear.
Earmuffs are devices that fit over the entire outer ear to form an air tight seal so the entire circumference of the ear canal is blocked from any noise, and they are held in place by an adjustable band. Earmuffs are not made to seal around eyeglasses or long hair, and the tension in the adjustable headband must be sufficient to hold the earmuffs firmly around the ear. It is important to know thaty earplugs must be snugly sealed so the entire circumference of the ear canal is blocked. Otherwise if they are improperly fitted, dirty or the plug is worn-out, it may not seal and can irritate the ear canal.
When earplugs or earmuffs are properly fitted they reduce noise 15 to 30 dB. The better quality of earplugs and earmuffs are approximately equal in sound reduction, however earplugs are better for low frequency noise and earmuffs for high frequency noise. When used together, earplugs and muffs usually adds 10 to 15 dB more protection than when either one is used alone. When noise exceeds 105 dB combining the use of both should be considered.
Wouldn’t It Be Easier To Just Stuff My Ears with Cotton?
When you use ordinary cotton halls or tissue paper wads and stuff them into the ear canals, they are very poor protectors; they reduce noise only by approximately 7 dB.
Are There Problems In Using Hearing Protectors?
Studies have shown that common problems found are that one-half of the workers wearing hearing protectors receive only 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.
Wearing a hearing protector continuously during an 8-hour work day with an average of 30 db of noise reduction, becomes equivalent to only 9 db of protection if taken off for one hour in the noise. The reason for 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.
The worker becomes exposed to 1,000 times more sound energy during the hour with unprotected ears, than if earplugs or muffs had been worn. 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.
When there is an incomplete air seal between the hearing protector and the skin, wearing earplugs and or muffs will do little good even if worn continuously while in noise. A useful sign that the hearing protectors are properly positioned is when using hearing protectors, you will hear your own voice louder and deeper.
While Wearing Hearing Protectors Can I Hear Other People and Machine Problems?
Hearing protectors enhance speech understanding in very noisy places, just as sunglasses help vision in very bright light. A normal hearing person wearing hearing protectors should be able to understand a regular conversation, even in a quiet setting. However, hearing protectors do slightly reduce the ability of those with damaged hearing or poor comprehension of language to understand normal conversation, It is essential however 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.
How Can I Tell If My Hearing Is Already Damaged?
Hearing loss does not happen overnight but usually develops over a period of several years. You might not notice it since it is painless and gradual. What you might notice however is a ringing or other sound in your ear (called tinnitus), which could he the result of long-term exposure to noise that has damaged the inner hearing nerve. Or, possibly 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 a sign of the beginning of high-frequency hearing loss; a hearing test should be able to 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,