WELCOME

HEARING CONSERVATION

CORPORATE SAFETY TRAINING

29 CFR 1910.95

WORK INVOLVING:

Chain saws Construction Lawn mowing Sand blasting Jack hammers Spray painting Musical performances Grinders, lathes, saws Manufacturing operations Exposure during maintenance duties

HEARING PROTECTION SITUATIONS

PRINCIPLES OF HEARING

EARCANAL

EARDRUM

OUTER EAR - MIDDLE EAR - INNER EAR

COCHLEA

HAMMERANVILSTIRRUP

AUDITORYNERVE

EUSTACHIANTUBE

THE COCHLEA AND THE INNER EAR

A fluid filled sound reception chamber Contains thousands of tiny hair cells The cells respond to sound waves made in the fluid The cells pass the sensation on to the auditory nerve

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PRINCIPLES OF HEARINGContinued

SENSORI-NEURAL HEARING LOSS

Noise-induced hearing loss Damages the hair cells or auditory nerves If the noise is stopped hair cells can bounce back Damage can be temporary

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SENSORI-NEURAL HEARING LOSS

If the noise continues hair cells can’t bounce back Damage can be permanent!

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NOISE MEASUREMENT

Decibel (dB) - A unit of measurement for sound pressure 085 Decibels (dB) is max for the average workday 140 Decibels (dB) is max for impulse or impact noise

No exposures in excess of 140dB peak sound pressure level are permitted. Impulsive or impact noise is considered to be those variations in noise levels at intervals of greater than one per second. Where the intervals are less than one second, it should be considered continuous. Source: ACGIH

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NOISE MEASUREMENT (Continued)

Sound is measured in two ways:

1. Frequency

2. Intensity

Frequency

Intensity

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FREQUENCY: The pitch -- how high or low the sound is. Expressed in cycles per second (CPS). Most people can hear pitches between 20 CPS and 20,000 CPS.

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INTENSITY: The loudness of sound. Expressed in units called decibels (dB). the more dB’s, the louder the sound. One decibel in the smallest unit of sound a person can hear.

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NOISE REDUCTION RATING (NRR): A single number measure of the amount of attenuation of sound that a hearing protection device will reduce outside sound to. Expressed in units of decibels (dB).

85dB

45dB

NRR 40dB

The TLV is the upper limit of noise as measured in decibels averaged over an eight hour work day to which an average healthy person may be repeatedly exposed on an all-day, everyday basis without suffering adverse hearing loss.

American Conference of Governmental Industrial Hygienist (ACGIH).

THRESHOLD LIMIT VALUE

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PRINCIPLES OF HEARINGContinued

THRESHOLD SHIFT

Hearing loss caused from noise can raise your “hearing-threshold” -- the degree of loudness at which you first begin to hear sound. Two types of shifts can occur:

1. Temporary threshold shift

2. Permanent threshold shift

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TEMPORARY THRESHOLD SHIFT

Most of the loss occurs in the first two hours Workers may not hear sound under 40db after work Hearing “returns” within two hours after exposure stops The loss can become permanent with long exposure

NOISE

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PERMANENT THRESHOLD SHIFT

Usually no physical signs Early signs may be tinnitus, ringing, muffling of sound Hearing no longer “returns” within two hours The loss starts in high frequencies and may spread

NOISE

WORK SOURCES & FACTORS AFFECTING HEARING:

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Age Pitch Loudness Surroundings Type of machines Position of source Length of exposure Previous ear trouble Distance from source Think about your personal work habits!

HOME SOURCES & FACTORS AFFECTING HEARING:

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Chain saws Race tracks Air hammers Trap shooting Starting pistols Musical groups Stereo systems Mowing the lawn Think about your personal lifestyle!

HOW LOUD IS LOUD?

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SOURCE DECIBELS

Rocket launching pad 180db Jet plane 140db Gunshot blast 140db Jackhammer 130db Automobile horn 120db Sandblasting 112db Rock music 110db Chain saw 100db Lawnmower 090db

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SOURCE DECIBELS

Alarm clock 080db Busy traffic 075db Vacuum cleaner 070db Normal conversation 065db Dishwasher 060db Average home 050db Quiet office 040db Whisper at 5 feet 030db Average threshold of hearing 015db

HOW LOUD IS LOUD?

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EXTREMELY HIGH, LOUD NOISE

Can cause “Traumatic Hearing Loss”

- May be caused by a single exposure to loud noise

- Less common than other types of hearing damage Can cause other effects in the work place

- Contributes to poor communication at work

- Unpleasant sound may cause fear, anger etc.

- Noise may cause fatigue or distractions

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WHEN IS NOISE TOO LOUD?

You have to raise your voice to be heard. You can’t hear someone less than 2 feet away from you. Speech sounds muffled after you leave a noisy area. You have ringing in your ears after exposure to noise.

- American Speech-Language-Hearing Association

HEARING DEVICE SELECTION

AN INDUSTRIAL HYGIENIST SHOULD BE CONSULTED

REGARDING THE TYPE OF HEARING PROTECTION TO BE

USED WITH YOUR OPERATION! THE FOLLOWING ARE GENERAL

GUIDELINES ONLY!

TYPES OF HEARING PROTECTION DEVICES

Ear Muffs (Circumaural)

Semi-Inserts (Semi-Aural)

Inserts (Aural)

Each type hasadvantages anddisadvantages

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EAR MUFFS (CIRCUMAURAL)

Surround the ear to reduce sound Very effective at reducing sound One size usually fits everyone Can be expensive Cleaning can be time-consuming Bulk can be a problem Can be uncomfortable in hot conditions Can be attached to: - Helmets - Bump caps - Hard hats

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SEMI-INSERTS (SEMI-AURAL)

Insert partially into the ear Snug fit is essential Moderately effective at reducing sound Do not always effectively seal ear canal One size fits all Large variety of shapes Cleaning is simple Bulk is not a problem Comfortable in hot conditions

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INSERTS (AURAL)

Training is essential to proper use Insert into the ear Snug fit is essential Moderately effective at reducing sound Do not always effectively seal ear canal Large variety of shapes Cleaning is simple Bulk is not a problem Comfortable in hot conditions

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INSERTS (Available in three forms)

Premolded Inserts - which may be universal- fitted or sized.

Custom Molded Inserts - which are either fabricated at a factory from an impression taken of the ear canal or designed so that the impression itself becomes the final device.

User Molded Inserts - which may be reusable or disposable, expand in the ear canal to form a seal after they are rolled and inserted.

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SELECTION CONSIDERATIONS

Will they effectively reduce sound levels? Comfort - will the users wear them? Cost Ease of use and repair Sizing and fitting ranges Dielectric considerations Training and skill for use Durability and life expectancy Anthropometric considerations Availability of replacement parts Size, weight, pressure, adjustability

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SELECTION CONSIDERATIONS

Visibility Pilferability Storage shelf life Climatic susceptibility Susceptibility to abuse Hygienic considerations Will the users like them? Susceptibility to alteration Confined space considerations Work environment susceptibility Compatibility with other equipment

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Do a fit test to ensure proper seal. Receive proper training in its use. Provide proper care for equipment. Ensure hazard levels are known. Review noise exposure limits. Receive annual and recurrent training. Select correct hearing protection devices.

HEARING DEVICE CHECKLIST:INSPECTIONCHECKLIST

Follow local policies and procedures. Wear only approved hearing protection devices. Wear only devices on which you have received training.

INSPECTION AND CARE OF HEARING PROTECTION EQUIPMENT

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