An Earful OfSound AdviceAbout Hearing Protection

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Your Hearing Conservation ProgramIt’s a noisy world we live in today —at work and at play. Unfortunately,some of that noise may damage yourears and prevent you from hearingimportant sounds tomorrow. To helpprotect your hearing, your employerhas established a hearing conservationprogram. It should include at least fivephases: sound surveys, noisecontrols, hearing evaluations,hearing protection, and education.Now it takes your participation tosucceed.

Sound Surveys

Sound surveys are used to identifywork locations where hazardous noiselevels exist. Employee exposures tonoise are monitored periodically with asound level meter or with a noisedosimeter that you may be asked towear.

Noise Controls

When possible, noise will be reducedor eliminated by modifying existingmachinery and placing noise limitspecifications on new equipment.

You can do your share by maintainingequipment in good operation, properlyusing noise controls when installed,and reporting noisy equipment to yoursupervisor when it needs attention.

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Hearing Evaluations

Hearing is measured with anaudiometer which sends tones to eachear through headphones. You listencarefully and respond each time youhear a tone. The levels at which youcan barely hear the tones are yourhearing threshold levels.

The audiogram chart records yourthresholds (measured in decibels) fortones at different pitches or frequencies(measured in Hertz). Normal thresholdsfall within the unshaded area on thechart. When hearing loss occurs thethresholds fall into the shaded areas,meaning sounds must be increased inlevel for you to hear them.

A baseline audiogram shows yourinitial hearing status, for comparison tofuture audiograms. Periodicaudiograms provide an update todetermine if your hearing conservationprogram is doing its job and if non-noise factors are affecting your hearing.A recheck audiogram or a professionalreferral may be needed if a significanthearing change occurs.

Periodic hearing evaluations show howyour hearing compares to normal for yourage. They are the only way to determinewhether your hearing is being conserved.Unusual changes alert you and youremployer to look for noise-related ormedical causes before it’s too late.

Normal audiogram and degrees of hearing loss

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Hearing Protection

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Hearing protectors can be veryeffective but only if they fitproperly and are worn correctly.Although labeled Noise ReductionRatings (NRRs) typically rangefrom 20-35 decibels, in practicethe protection that normally can beachieved is about 10-20 decibels.

The more carefully you select andwear hearing protectors, the higheryour protection will be. Hearingprotectors may feel uncomfortableat first, but give yourself a chanceto get used to them, just as you dowith a new pair of shoes orglasses.

Protector Type Description

Formable Plugs Formable plugs are compressed or shapedprior to insertion. The most popular varietyis made of expandable, slow-recovery foam.One size fits most everyone. Once in theear, foam plugs gently expand to providea snug and secure custom fit.

Premolded Plugs Premolded plugs are made from flexiblematerials that are preformed to fit the ear.They are generally available with a joiningcord to prevent loss. Although the versionpictured at the left is a one-sized product,many premolded plugs are sold in two ormore sizes and must be individually sizedfor each ear. If after a week or so you’vebeen unable to get used to your earplugs,check with the fitter to try another size,type, or brand of hearing protector.

How to Use Care & Cleaning

Slowly roll and compress foamplugs into a very thin cylinder. Whilecompressed, insert plug well into theearcanal. Fitting is easier if you reach

around the head topull the earoutward and

upwardduringinsertion.

Keep the plugs clean and free frommaterial that can irritate the earcanal.They may be washed in mild liquiddetergent and warm water. Squeeze excess water from the plugs and air dry.Washing may be repeated several times.Discard plugs if theynoticeably changetheir firmness or donot re-expand totheir original sizeand shape.

Reach around the back of your headand pull outward and upward on the

ear while insertingthe plug until you

feel it sealing. Thismay seem

tight at first,especiallyif you’venever worn

earplugs.

Premolded plugs will normally last severalmonths or more depending upon the type,and upon your work environment, hygiene,and body chemistry. They should bereplaced if they shrink,harden, tear, crack, orbecome permanentlydeformed. Wash them inwarm soapy water andrinse well. When dry,store them in a carryingcase.

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Earplug Fitting Tip. Press firmlycupped hands over your ears whilelistening to a steady noise. Withproperly fitted plugs the noise levelsshould be about the same whether ornot the ears are covered.

Hearing Protection

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Protector Type Description

Semi-insert Device Semi-inserts, also called canal caps,consist of pods or flexible tips on alightweight headband. Because they arequick to put on and take off and easy tostore around the neck, they are ideal forintermittent use. They provide lessprotection than either plugs or muffs andaren’t usually recommended forcontinuous long-term wearing.

Earmuffs Earmuffs have rigid cups with soft plasticcushions that seal around the ears toblock noise. Foam-filled cushions areusually preferred over liquid-filled versionsbecause they are lighter, more durable,and equally protective. For very loudnoises, wear muffs and plugs together foran additional 5-10 dB or so of protection.

Initially you may be concerned thatyou’ll be unable to hearconversation, machinery sounds,and warning signals while wearinghearing protection. However, unlessyou already have a significanthearing loss you’ll be surprisedhow well you can hear while innoise. And when you properly wear

hearing protectors you’ll be able tohear as well at day’s end as whenyou started in the morning. Peoplewith hearing loss also benefit, sincewithout protection noise willcontinue to damage their hearinguntil it is difficult to distinguishsounds under even the best ofconditions.

Hearing Protector Fitting Tip. When eithera plug or muff is properly fitted, the sound ofyour own voice should change, becomingdeeper, hollow, or muffled. If you don’t hearthe change, or if it isn’t the same in bothears, you haven’t obtained a proper fit and acoustic seal in eitherone or both ears.

Tip: Talking in noise. When you wear plugs or muffs in noise youtend to speak less loudly than otherwise because the protectormakes your own voice seem louder and the surrounding noisesseem quieter. So, you have to speak up — speak more loudly thanyou think you need to. Others will appreciate this, and yourmessage will be better understood.

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How to Use Care & Cleaning

Hold the large ends of the pods andswivel them to direct the tips into theearcanal openings. Firmly push and

wiggle the podsinto the canalsuntil a snug seal

is obtained. Pullingon the outer ear

while pushing onthe pods will behelpful to mostwearers.

Most semi-inserts can be cleaned in thesame way as premolded earplugs. Sincethe headband holds the tips in place toprovide an acoustic seal,don’ttamper withit or theprotection thedeviceprovides maybe reduced.

Muffs must fully enclose the ears toseal against the head. Adjust theheadband so cushions exert evenpressure around the ears to get thebest noise reduction. Pull hair back and

out from beneath thecushions. Don’t

store pencilsor wear caps

under thecushions.

Cushions can be cleaned with warm soapywater and rinsed thoroughly. Do not usealcohol or solvents. Cushions normallyneed replacing twice a year or more -whenever they become stiff, cracked,or do not seal. Don’tmodify earmuffs in anyway, and especially donot stretch or abusethe headbands asthis will reduceyour protection.

Your HearingWhy and when to protect it

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Effects of Age and Noise on Hearing

Hearing loss from the natural agingprocess causes a gradual hearing decline,as shown in the figure to the right. Itaffects mainly the ability to clearly hearhigh-pitched sounds such as children’svoices, rustling leaves, and some musicalinstruments.

Although age-effect hearing loss up throughage 60 does not usually impair one’sability to hear and understand speech,problems occur when noise-induced loss isadded to age loss. With noise damage,even a 30-year-old can have troublelistening in situations in which backgroundsound is present, such as in restaurants andother social situations.

Loss from aging plus noiseexposure at 95 dBA*

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Hair cells within thecochlea of the innerear respond to vibra-tions by generatingnerve impulses. Thebrain interprets thisas sound.

The middle ear contains a chainof three tiny bones, called ossicles,which link the eardrum to the innerear. When sound waves strike theeardrum, the ossicles conduct thevibrations to the cochlea in the inner ear.

How We HearHealthy inner-ear hair cells are the key to good hearing. Althoughsome die off naturally as you age, many more are killed early if yourears aren’t protected from harmful noise.

The outer ear collects andfunnels sound waves alongthe earcanal to the eardrum.

You Don’t Get “Used to Noise”

Noise does not have to be uncomfortablyloud to be damaging. You may eventhink your ears are “used to the noise,”but what has probably happened is thathearing loss has already begun. Howquickly hearing loss occurs depends onthe intensity of the noise, its duration,and how often the exposure occurs.

A Rule of Thumb

When you feel the need to shout in orderto be heard three feet away, the noiselevels are probably 85 dBA or more andhearing protectors are recommended.

Noise Damage Indicators

If sounds seem muffled or softer afternoise exposure, your hearing is affectedby a temporary threshold shift whichwarns that your ears have beenoverexposed. If you repeatedly exposeyour ears without protection, the shiftcan worsen and become permanent,resulting in untreatable damage to yourhearing ability.

Another warning sign is tinnitus — aringing, buzzing, or whistling in yourhead. It’s like a “sunburn” of the hair cellsof your inner ear, indicating that they havebeen irritated and overworked. Tinnitus isespecially noticeable in a quiet place, suchas when trying to go to sleep at night. Ifyou don’t protect your ears from noise,tinnitus can become a permanent, constantannoyance in your life.

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Typical Sound Levels

Decibels (dBA)

140 Pain Threshold

Jet Takeoff 130

Basketball 120Game

Crowd Noise

Large 110Stamping Press

Chain Saw 100

Drilling Concrete 90Leaf Blower

Vacuum 80Cleaner

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Conversation 60

Floor Fan 50

Quiet 40Library

Rice 30Krispies

Watch 20Ticking

Quiet 10Wilderness

(no wind)

0 Threshold of Hearing

Dual protection may beneeded.

Short exposures cancause permanent loss.

Prolonged exposure causes moderate to severe loss. Wearhearing protectors with extra care.

Prolonged exposureexposure causes mild tomoderate loss. Hearingprotectors required.

Prolonged exposurecauses slight hearingloss. Hearing protectorsrecommended.

Do Yourself A Favor —Save Your Hearing!

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Sounds You Want to Hear

A hearing-impaired person may not be ableto enjoy birds singing or cats purring, anddistortion from damaged hair cells maymake music seem like “just a racket.” Itbecomes difficult to detect problems withtools or car engines by listening forchanges in the sounds they make. Hearing-impaired people worry about getting hurtby missing danger signals such as warningbeepers.

Person-to-Person Communication

Most important, a person with hearing lossmay not hear or understand familymembers and friends, particularly womenand children with high-pitched voices. Theindividual will confuse similar-soundingwords and mistake the message.Embarrassed to ask the speaker to repeat,the listener may just “tune out.” Conversingin groups is most difficult, especially ifthere is background noise. People withhearing loss often become socially isolatedas others find it too much trouble to speakto them. What’s more, hearing aids can’tcompletely correct the problem becauselouder sounds are not necessarily clearer tothe damaged ear.

Keep Track of Your Hearing

Check your current audiogramsagainst past results. Pat yourself onthe back if your thresholds are stable.If your thresholds are changing, aprofessional will review youraudiograms along with informationabout your ear health and noiseexposures to identify possible causes.If hearing changes appear to be noise-related, your employer may suggestdifferent hearing protectors, retrainyou in their use, or recommend youwear them during off-the-jobexposures.

Remember:You Need Your Hearing!

These comments from people withnoise-induced hearing loss show whyit is worth the effort to properly wearhearing protectors: your quality of lifedepends on keeping your goodhearing. Once hearing is lost it is goneforever.

Even if you already have some hearingloss, it is still essential to wear hearingprotectors from now on to prevent theloss from worsening. It’s never toolate to start conserving your hearing!

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Noise Is All AroundNoise doesn’t stop after leaving the workplace, andneither does the need for hearing protection. Beaware of noisy situations so you can protectyourself and enjoy a lifetime of good hearing.

Gunshots.Protection is neededwhen shooting at bothindoor and outdoorranges.

Power Tools.Semi-insert devices orearmuffs can be effec-tive and convenient pro-tection for these inter-mittent exposures.

Chain Saws.Hearing protection is amust whenever operatinga chain saw.

Aircraft.When flying in small air-craft, foam earplugs orother hearing protectorsare suggested.

Music.If it’s too loud, even musiccan be harmful to youhearing. Keep a safe dis-tance from loudspeakers,and if necessary, wearhearing protection.

Radio Headphones.Be smart — keep the musicturned to safe levels. As arule of thumb, while listen-ing to headphones youshould still be able to hearothers speaking to you froma few feet away.

AEARO COMPANY8001 Woodland DriveIndianapolis, Indiana 46278telephone: (317) 692-6666 / (800) 225-9038fax: (800) 488-8007

AEARO CANADA LTD.6889 Rexwood RoadUnits 8 & 9Mississauga, Ontario L4V 1R2telephone: (905) 795-0700fax: (905) 564-5250

AEARO LTD.First Avenue, Poynton, Stockport, Cheshire England SK12 1FJtelephone: 0 1625 878320fax: 01625 877348

Written by:Elliott H. Berger, M.S., Senior Scientist, Auditory ResearchJulia D. Royster, Ph.D., President, Environmental Noise Consultants, Inc.With Contributions by:Larry H. Royster, Ph.D., Professor, North Carolina State University

© 2002 Aearo CompanyFirst Printing 1988

LIT. Code 33012