us army: hearing loss prevention short

8/14/2019 US Army: Hearing Loss Prevention short

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1LT SCOTT FORBES 1LT SCOTT FORBES

285-6186/6288 285-6186/6288



DID YOU KNOW…...?-Noise-induced hearing loss is the

number one occupational disability

-It is generally painless-It is progressive over time

-

It is permanent-IT IS PREVENTABLE!!!

THE THE

4 PS 4 PS



HOW DO WE HEAR?HOW DO WE HEAR?



SOUND RECEPTORSSOUND RECEPTORS



DAMAGED HAIR CELLSDAMAGED HAIR CELLS



6

WHAT IS NOISE?

• Simply stated…noise is any

unwanted sound



7

WAYS TO CHARACTERIZE

OF NOISE• FREQUENCY - perceived as pitch

• INTENSITY - perceived as loudness

• NATURE - steady-state vs. impulse/impact

• DURATION - length of time exposed



Noise Induced Hearing Loss

u Initially, exposure to noise causes aloss of sensitivity to high frequency

(high pitch) sound.uContinued exposure results in damage

to mid frequency region as well.u

One can experience progressive highfrequency hearing loss and not beaware of it until it becomes severe(doesn’t affect loudness perception).



HOW CAN IT HAPPEN?

ACOUSTIC TRAUMA – ONE TIMEEXPOSURE TO LOUD SOUND

OR

DAILY EXPOSURES TOMODERATELY LOUD SOUNDS



HOW DO WE KNOW

SOMETHING IS TOO LOUD?• Could use 3 foot rule

– If you have to raise your voice to be

heard by someone standing within 3 foot(arm’s length) then the level is mostlikely above the hazardous noise level

or– Objectively measure loudness withproper equipment



When isWhen is noisenoise scientificallyscientifically

defined to be adefined to be a hazardhazard??-Duration of exposure, intensity (volume)

of sound, repeated exposure, individual

susceptibility

-85dBA for steady-state noise sources

-140dBP for impulse/impact noise sources



Steady-StateSteady-State

Noise ExamplesNoise Examplesu Rustling Leaves 20dB

u Conversation 60dB

uAutomobile 70dB

u Alarm Clock 80dB

u Screaming Child 90dB

u Pneumatic Drill 100dBu Helicopter 110dB

u Live Concert 130dB



Loss of hearing sensitivity due to

hazardous noise exposures fromeither steady state noise orimpulse noise does occur even

before we can measure thechange!….

And it does carry negativeconsequences!!!



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PTS vs. TTS• A permanent threshold shift (PTS) vs. a

temporary threshold shift (TTS)

• Bounce-back effect…not complete recovery

• Immediate medical referral (Audiology /ENT)



16

Permanent Effects of Noise

Induced Hearing Loss

-Difficulty understanding conversation,

particularly in background noise…highfrequency hearing loss affects abilityto hear consonants. Quality ofenvironmental sound is diminished.

-”Ringing in Ears” - tinnitus



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WHAT ABOUT EFFECTS

ON MISSION ???

• Hearing vs. vision in tacticalenvironment– Darkness

– 360 degrees

– 24/7



What About the Soldier whoWhat About the Soldier whoCan’t Hear Within NormalCan’t Hear Within Normal

Hearing Range?Hearing Range?

uA normal listener can hearufootsteps at 100 metersuvoices at 180 metersurifle bolt closing at 1000 meters

u A person with a hearing loss can hearufootsteps at < 1 meter

uvoices at 32 metersurifle bolt closing at 46 meters



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THINK ABOUT IT…

-Listening posts

-Walking point onpatrol

-Call for fire

-Urban Warfare



Annual Hearing TestingAnnual Hearing Testing

ÌWhy do annually?ÌFeedback BEFORE it becomes a

problem….not five years down the roadwhen it definitely is a problem

ÌWhat is your score???Ì Are you practicing good hearing

conservation or aren’t you???



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BOTTOM LINE

• If you are exposing yourself to

hazardous noise levelsunprotected…it’s not a matterof whether you will develop

hearing loss but when you willdevelop hearing loss…the oddsare VERY RARELY beaten.



HEARING PROTECTION

¢The only thing standing between youand a potential permanent hearing

loss!!!!!



But I Can’t Wear HearingBut I Can’t Wear Hearing

Protection Because…...Protection Because…...

ÌMy ears will become infected

ÌThey hurt my earsÌI can’t hear to do my jobÌI can’t hear sounds needed to hunt,

etc., etc.ÌThinking short-term instead of long-

term



Approved Types of HPD’sApproved Types of HPD’s

²Earplugs²Pre-formed

²Hand-formed

²Noise Muffs

²Helmets



NOISE REDUCTIONNOISE REDUCTION

RATING (NRR)RATING (NRR)rAll hearing protection deviceshave a Noise Reduction Rating(NRR)rField testing suggests that the

actual NRR is approximatelyhalf of what is listed on thepackage



PRE-FORMED EARPLUGSPRE-FORMED EARPLUGS• Single Flange:

– (NRR)=23dB

– 5 color-coded sizes:• White (Extra Small)- 10% of

the population

• Green (Small)- 25%

• Orange (Medium)-30%

• Blue (Large)- 40%• Red (Extra Large)- 25%



FITTING TECHNIQUEFITTING TECHNIQUE



PRE-FORMED EARPLUGSPRE-FORMED EARPLUGS• Triple Flange:

– NRR= 26dB

– 3 color coded sizes:

• Green (Small)= 10% of thepopulation

• Orange (Medium)=80%

• Blue (Large)= 30%



Characteristics Of A GoodCharacteristics Of A Good

Pre-formed Earplug FitPre-formed Earplug Fit²Voices sound muffled

²“Vacuum” effect

²Comfortable

²Single flange tab facing towardback of ear

²Largest flange of triple flange isflush against ear canal opening



HAND-FORMED EARPLUGSHAND-FORMED EARPLUGS Noise Reduction Rating (NRR)=29dB



Fitting TechniqueFitting Technique



Circumaural Noise MuffsCircumaural Noise Muffs

Noise Reduction Rating(NRR)=23dB



Fitting TechniqueFitting Technique

²Noise muffs should seal around theear

²Replace ear cushions when cracked orworn²Certain types of muffs allow

placement of the headband on top ofthe head, behind the head, or underthe chin



Care and Maintenance ofCare and Maintenance ofall HEARING PROTECTIVEall HEARING PROTECTIVE

DEVICESDEVICES uKeep clean with mild soap and water

and dry before usinguReplace when material

hardens/cracks or does not cleanu

Check for cracks on earphone seals,headband tension and replace asneeded



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Helmets: For Specific

Operational Uses

• Aviators, aviationcrews

• Tankers

• Amphibious vehiclecrew members



COMBAT EARPLUGSCOMBAT EARPLUGS•Insert YELLOW plugs for

weapons fire in dismountedmode.

• Insert OLIVE DRAB plugs for

steady state noise in andaround aircraft, noisy vehiclesand watercraft, etc.

• Keep filter holes free of earwax and other debris.

• Check proper insertion for slight tension by gently tuggingon plugs.

• Ensure that plugs are cleaned with soap and water and drywhen returned to case.



Where to get HearingWhere to get Hearing

ProtectionProtection rPre-formed – fitting done at Thomas

Moore Health Clinic on walk-in basis

rAll other types provided by unit and shouldbe included in budget

O Wh d



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One more time…When do Ineed to wear protection?

• Steady state noise measured at85dBA or greater

• Impulse noise measured at 140dBA orgreater



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Are HPDs always enough?

• Some military noise exposure may

exceed the protection offered byHPDs

• Synergistic effects

• Permanent damage can be minimizedwith HPD use



42

OTHER PROTECTIVE

MEASURES

• Administrative Controls

• Double protection

• Medical intervention???



43

ADMINISTRATIVE

CONTROLS

• Limit exposuretime by

implementing shiftwork schedules



44

DOUBLING UP!

• Steady state

noises 120dBA orgreater

• Use of insert

earplugs andcircumauralearmuffs together



45

Medical Research

(on the horizon) • Hazardous exposure initiates inner ear

oxidative process which results in hair celldeath cycle

• New medication may be able to limit permanent damage by arresting oxidativeprocess

• Time sensitive• NOT A SUB FOR HPDs!



Listening through HPDs takespractice but the thresholdshift caused from wearing

them is temporary…the shift

caused from not protectingyourself could bepermanent!!!!



TO SUMMARIZE……

² HEARING LOSS HAPPENS!

² Noise induced hearing loss is 100%

preventable

² Your hearing health starts with YOU while

at work or home

² If YOU don’t protect it YOU will lose it



QUESTIONS??QUESTIONS??

Fort Hood Hearing Conservation Fort Hood Hearing Conservation Section Section

us army: hearing loss prevention short

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