Hearing Conservation Program

NRCCSINGAPORE

21 March 2006

References

29 CFR 1910.95, Occupational Noise Exposure

OPNAVINST 5100.23G, NAVOSH Program Manual, Chapter 18

Noise Any unwanted sound--created by many

different sources:TrafficIndustrial equipment and toolsMusicGunfire exercisesVentilation

Excessive noise--over time and certain levels--can cause hearing loss

Noise Exposure

Determined by:Duration of exposureType of noise

• Continuous

• Impulse

IntensityFrequency

Causes of Hearing Loss

Age Disease (Middle or Inner Ear) Trauma Drugs (the “…mycins, tetracycline) Noise exposure

How Hearing Loss Occurs

Damage to the Ear Outer ear--

Catches dirt and particles in the canal that contains cerumen or wax

Middle ear--Has bones (malleus, incus, stapes) and ear drum which

can rupture from sudden high sound pressure levels

Inner ear--Has cochlea with tiny hair cells connected to nerves.

Damage is irreversible Cochlea

Middle ear

Measuring Sound

Terminology

Frequency Measured in hertz (Hz) or cycles per secondDetermines how high or low the pitch sounds

IntensityMeasured in decibels (dB)Determines how “loud” a noise soundsLogarithmic scaleExchange (doubling) rate (5 for Navy) ---------------Audiograms---------------------------------Audiograms------------------

Frequency Weighting Scales

Other Information

Ability to hear well depends onPitch of the soundAge of the individualDistance from noise sourcePrevious noise exposuresEnvironment (surroundings)

Other Information Sound level meters used to measure noise

levels20 Decibels (dB)--faint sound (like a

whisper)150 Decibels (dB)--F-14 at takeoff on flight

deck

Navy Industrial Hygiene Officers (IHO) conduct noise surveys

Hearing Conservation Program

Program Objective The objective of the Hearing

Conservation Program is to prevent hearing loss as a result of exposure to hazardous noise.

How would YOU like to own this?

Program Elements Identifying noise hazardous areas Engineering controls to reduce the hazard Posting of noise hazardous areas Providing hearing protection to personnel Medical monitoring (audiograms) Education and training

Identifying Noise Hazardous Areas

Limits for continuous noise exposureDOD = 85 dBAOSHA = Used to be 90 dBA, now reduced to 85 dBAImpact (Impulse) noise limit = 140 dB

84 dBA or less--OK for personnel 8 hours a day, five days a week with no ill effects.

Above 84 dBA--Navy considers noise hazardous

Identifying Noise Hazardous Areas

Sound level surveys conducted to determine which spaces routinely haveContinuous noise >84 dBAImpact noise >140 dB

Survey documents retained for 50 yearsReadings repeated if equipment is

added/changedReadings reviewed as part of IH survey

Engineering Controls Noise can be decreased by changes in design

or imposing controlsDamping material or sound curtains around

equipmentAcoustical tiles for classroomsRubber insulating pads at metal-to-metal interfaceMoving noise equipment to isolated location

Engineering controls must be considered FIRST, prior to resorting to PPE

Posting Noise Hazard Signs Used when engineering controls do not work,

or are not feasible Use Noise Hazard Warning Labels to mark

hazardsLarge warning decals for entire areas (NAVMED 6260/2)

Small warning labels (green or orange) for individual equipment (NAVMED 6260/2A)

Post areas as DOUBLE Hearing Protection Required if sound levels >104 dBA

Personal Protection

Used as last resort--when exposures cannot be controlled by any other means

Ear plugs and muffsMechanically block noise from earRated for specific Noise Reduction Rating

(NRR)--reduce decibel levels reaching the ear by the number listed on the package

Actual NRR likely less than advertised NRR

Personal Protection Ear plugs

Fit into ear canalFitted/Flanged types issued by MedicalDisposable foam plugs don’t require fitting--also have

highest NRR (about 30dB)

Ear muffsFit over outer earHave NRR of 24-28 dBEar caps--like plugs with a head band--NRR of about

22 dB

Personal Protection

Single protectionPlugs or muffsRequired when continuous sound levels >84dB

continuous or 140 to 165 dB peakRequired when exposed to noise from gunfire,

artillery or missile firing

All personnel should be fitted for insert hearing protection. Recruits at recruit depot .

Personal Protection

Double protectionRequired when continuous sound levels

>104dBAUse combination of ear plugs and ear muffs

Must be kept clean and in good conditionDirty plugs may cause infectionsMuffs with hardened seals DO NOT protect

Medical Monitoring Baseline and routine testing required for all

personnel routinely working in noise hazardous areas

Maintain roster of personnel routinely working in noise hazardous areas

All Navy and Marine Corps personnel given baseline audiogram (DD 2215) when entering the service

Annual audiograms (DD2216) given to personnel assigned work in noise hazardous areas

Significant Threshold Shift (STS)

A change of 15 dB or more at 1000, 2000, 3000, or 4000 Hz in either ear

OR…

An average change of 10 dB or more at 2000, 3000, or 4000 Hz in either ear

Disposition Following Monitoring Hearing Tests

If patient has a STS: follow-up hearing test after 14 hours noise free

If STS still present, conductive hearing loss may be ruled out by tympanometry and otoscopy by MDR

Second follow-up audiogram may be on same day

May refer to audiologist at any point

Disposition Following Monitoring Hearing Tests

If second follow-up still shows STS, must refer to audiologist

Termination audiograms given to personnel when leaving the service

Questions ???