Hansen – managing safely 1 Noise at Work Mark Mallen Group Health and Safety Manager.

Hansen – managing safely 1

Noise at WorkNoise at Work

Mark MallenGroup Health and Safety Manager


IntroductionIntroduction

Noise at work and how it can affect you


Objectives Objectives What is noise? What is sound? How do we hear? Measuring noise? Hearing Loss The Law

– Employer duties– Employee duties

PPE– Where, what and when


Content Content

What is noise? Sound How do we hear? The measurement of noise Hearing Loss The Law - Noise at Work Regulations 1989 - The Control of Noise at Work Regulations 2005 Information, instruction, and training - What we need to tell you


What is Noise?What is Noise?

Noise – Noise is unwanted sound.– One person’s music could be another’s

noise!– The ear does not differentiate between

noise and sound - The brain does that!


What is Noise?What is Noise?

EffectsShort term

– Annoy– Distract

Long term– Deafness– Tinnitus– Noise Induced Hearing Loss (NIHL)


SoundSound

The sensation produced via the ear, – results from fluctuations in air pressure– Caused by vibrating air molecules– The source of the sound vibrates – Creates a sound pressure wave


SoundSound Like ripples on a pond – sound

pressure wave


SoundSound

A Sound Wave– created by a vibrating object:

The vocal chordsA guitar string A machineTraffic The diaphragm of a radio speaker


SoundSound

Air moves back and forth– The frequency of a wave

If a particle of air undergoes 1000 vibrations in 2 seconds– Then the frequency of the wave is 500

vibrations per secondThe unit of frequency is the hertz

(abbreviated Hz), where:– 1 Hertz = 1 vibration/second


SoundSound

The human ear detects– Ranges between approximately 20 Hz to

20 000 HzAny sound less than 20 Hz

– InfrasoundAny sound above 20 000 Hz

– Ultrasound


How do we hear Sound?How do we hear Sound?

The Ear– The outer ear

Collects and channels sound to the middle ear.

– The middle ear Transforms the energy of a sound wave into internal

vibrations via a bone structure.

– The inner ear The inner ear transforms these vibrations into nerve

impulses, which can be transmitted to the brain.


The EarThe Ear


The Outer EarThe Outer Ear

Consists of an earflap and an ear canalThe earflap protects the middle ear and

eardrum It also channels sound waves to the

eardrumSound is still a sound pressure waveAt the eardrum, the wave converts into

vibrations


The Middle EarThe Middle EarAn eardrum

– A membrane, which connects to the hammer

Three tiny, interconnected bones– Hammer, anvil & stirrup– Act as levers to amplify the sound wave– The stirrup concentrates sound wave by 15– This enhances our ability of hear faint sounds


The Middle EarThe Middle Ear The Eustachian tube

– Connects the middle ear via a tube to the mouth

– Allows for the equalization of pressure within the air-filled cavities

– When clogged i.e. During a cold, the ear cavity is unable to equalise pressure; often leads to earaches and other pains

The stirrup transmits vibrations to the inner ear, via the oval window


The Inner EarThe Inner Ear Full of a water like fluid The stirrup creates a wave within this fluid The inner ear consists of

– A cochlea– The semicircular canals– And the auditory nerve

The fluid and nerve cells of the semicircular canals provide no roll in the task of hearing– They serve as accelerometers for detecting

accelerated movements– Assist in the task of maintaining balance


The EarThe Ear


The CochleaThe Cochlea Snail-shaped organ

– Lined with over 20 000 hair-like nerve cells– These nerve cells differ in length by minuscule amounts– They have different degrees of resiliency to the fluid– The hair-like nerve cells are set in motion by the wave– Each hair cell has a natural sensitivity to a particular

frequency of vibration– When the wave matches the natural frequency of the

nerve cell, an electrical impulse is released– Which passes along the auditory nerve to the brain– The brain then interprets the qualities of the sound upon

reception of these electric nerve impulses


The Measurement Of NoiseThe Measurement Of Noise Decibels

– Humans have very sensitive ears– The lowest sound corresponds to the displacement of air

particles by one-billionth of a centimetre– Known as the ‘threshold of hearing’– The most intense sound

Which the ear can detect without suffering any damage– More than one billion times more intense– Known as the ‘threshold of pain’

Since the range of intensities is so large, a scale based on multiples of 10 is used– Known as a logarithmic scale– The scale for measuring intensity is the decibel scale

Decibels are written as: db At the ear db (A)


The Measurement of NoiseThe Measurement of Noise

The threshold of hearing is assigned a sound level of 0 decibels, abbreviated 0 dB.

A sound, which is 10 times more intense, is assigned a sound level of 10 dB.

A sound, which is 10 x 10 or 100 times more intense, assigned a sound level of 20 db.

A sound, which is 10 x 10 x 10 or 1000 times more intense, is assigned a sound level of 30 db.

A sound, which is 10 x 10 x 10 x 10 or 10000 times more intense, is assigned a sound level of 40 db.

This scale is based on powers or multiples of 10


Typical Noise LevelsTypical Noise LevelsSource Intensity Level

Threshold of Hearing - TOH 0 dB

Rustling Leaves 10 dB

Whisper 20 dB

Normal Conversation 60 dB

Busy Street Traffic 70 dB

Vacuum Cleaner 80 dB

Large Orchestra 98 dB

Walkman at Maximum Level 100 dB

Front Rows of Rock Concert 110 dB

Threshold of Pain - TOP 130 dB

Military Jet Takeoff 140 dB

Instant Perforation of Eardrum 160 dB

Remember that a doubling in sound represents an increase of only 3dB


Hearing LossHearing Loss The ear can be easily damaged, by:

– Medical conditions– Accidents– Drugs– Congenital conditions– Social activities– Prolonged exposure to high noise levels

Workers at risk of hearing damage are usually :– Metal work– Construction– Quarrying– Steel work– Mining– Noisy industries

Exposure above 90 db (A) is likely to cause damage This is known as noise induced hearing loss


Noise Induced Hearing LossNoise Induced Hearing Loss

Chronic NIHLDamage is caused to the sensitive

cells in the cochleaOccurs gradually from exposure to less

intense noise levels


Noise Induced Hearing LossNoise Induced Hearing Loss Associated with exposure to high intensity,

continuous noise The amount of sound that is capable of producing

cochlear damage and subsequent hearing loss is based upon– The equal energy concept

Therefore, it is the total sound energy delivered to the cochlea that is relevant in predicting injury and hearing loss

Both an intense sound presented to the ear for a short period and a less intense sound that is presented for a longer period will produce equal damage to the inner ear


Noise Induced Hearing LossNoise Induced Hearing Loss Chronic NIHL has two phases Temporary Threshold Shift – TTS

– The first stage– Brief hearing loss, ‘ringing in the ears’ – Completely resolves after a period of rest

auditory fatigue

– Most studies indicate that no sensory cell damage occurs

– After repeated exposure to noises – A Permanent Threshold Shift - PTS will occur


Noise Induced Hearing LossNoise Induced Hearing Loss Permanent threshold shift – PTS

– This is the second stage of chronic NIHL– An irreversible increase in hearing thresholds– Irreversible hair cell damage

Once you have it, it is too late– Sufferers report difficulty understanding speech

rather than hearing speech– Particularly noticeable in environments with

significant background noise



An ‘normal’ audiogram


Noise Induced Hearing LossNoise Induced Hearing Loss An audiogram showing the classic ‘dip’ in hearing performance

– Characterised by a loss of consonant discrimination – Consonant sounds such as f, s, t, d, sh, and k are essential

to the intelligibility of speech



Socioacusis– even people with quiet jobs may suffer– Such non-occupational NIHL is also called

socioacusis. Sources of non-occupational noise include:

– Gunfire– Loud music – Open vehicles – Power tools


The LawThe Law

Noise at Work Regulations 1989 Place responsibilities

– employers– Employees– People who make and supply noisy machinery

The regulations introduced three thresholds:– First Action Level - 85dB(A)– Second Action Level - 90dB(A)– Peak Action Level - 200 Pascals or 140dB

The sound at the ear is represented by (A)


The LawThe Law First Action Level - LEP, d 85dB(A)

– When you have to raise your voice to be heard at 2 metres– The employee must be trained– hearing protection must be made available upon request

Second Action Level - LEP, d 90dB(A)– When you have to raise your voice to be heard at 1 metre– A noise reduction programme must be implemented– Areas must be marked– Employees must be provided with hearing protection,

which must be worn Peak Action Level - 200 Pascals or 140dB

– This relates to sudden noise– the duties are similar to those required by the second

action level


The LawThe Law

Employers duties– Get the noise levels assessed by competent people– Keep a record– Where exposure is at, or above, any of the action levels:

Inform personnel that there is a noise hazard Inform them of what to do Where the exposure needs to be controlled, quieten

the workplace, if this can be done Between the first and second action levels

– Provide ear protection (ear muffs or plugs)– Inform workers of the risk to their hearing


The LawThe Law

Where use of protection is compulsory– Ear protection zones should be marked– Make sure that everyone who goes into a marked zone,

even for a short time, uses ear protection– Check to make sure the control measures are working– Make sure the equipment you provide is kept in good

condition If people work in noise at, or above, the second or

the peak action level The regulations still require the reduction of noise

exposure by means other than ear protectors, as far as this is reasonably practicable


The LawThe Law

Employees duties– Wear the ear protection (earplugs or earmuffs) provided– At the second or peak action levels might be reached– Every entry into an area marked as an ear protection zone

Use any other equipment the employer provides– For example, if the machine is meant to have a silencer

fitted- don't take it off Look after any equipment provided under the

regulations Report any equipment defects


The Law –Changes Are Coming!The Law –Changes Are Coming! The control of noise at work regulations 2005

Come into force on 6th April 2006 Exposure limit values and action values The lower exposure action values

– A daily or weekly personal noise exposure of 80 db (A)– A peak sound pressure of 135 db

The upper exposure action values – A daily or weekly personal noise exposure of 85 db (A)– A peak sound pressure of 137 db

The exposure limit values A peak sound pressure of 140 db


Information, Instruction, And Information, Instruction, And TrainingTraining What we need to tell you

– Exposure areas above the lower exposure action values– What we are doing to control risks and exposures– Where and how people can obtain hearing protection– How to report defects in hearing protection and noise-

control equipment– Duties under the noise regulations 2005– What you should do to minimise the risk

Such as the proper way to use hearing protection and other noise-control equipment

How to look after it and store it, and where to use it


Exposure areasExposure areas


Exposure areasExposure areas


Information, Instruction, And Information, Instruction, And TrainingTraining What we are doing to control risks and exposures

– Established advisory hearing protection zones– Sourcing noise reduction blades– Provide hearing protection

Where and how people can obtain hearing protection– Freely available from dispensers or production manager

How to report defects in hearing protection and noise-control equipment– Report to supervisor or manager


Information, Instruction, And Information, Instruction, And TrainingTrainingDuties under the noise regulations

2005– Wear the ear protection (earplugs or

earmuffs) provided– Use any other equipment the employer

provides under the regulations– Look after any equipment provided under

the regulations– Report any equipment defects


Information, instruction, and Information, instruction, and trainingtraining Earmuffs

– Make sure they totally cover your ears, – Fit tightly and there are no gaps around the

seals. – Don’t let hair, jewellery, glasses, hats etc

interfere with the seal.– Try and keep the seals and the insides clean. – Don’t stretch the headband too much – make

sure it keeps its tension.


Information, Instruction, And Information, Instruction, And TrainingTrainingEarmuffs


Information, Instruction, And Information, Instruction, And TrainingTraining Earplugs

– They can be difficult to fit properly– Practice fitting them and get help if you are having trouble– They can look like they are fitted properly– Clean your hands before you fit earplugs, and don’t share

them– Some types you use only once– Others can be re-used and even washed– Make sure you know which type you have

Semi-inserts/caps– Follow the same advice as for earplugs– Make sure any headband keeps its tension


Information, Instruction, And Information, Instruction, And TrainingTrainingEarplugs


Information, Instruction, And Information, Instruction, And TrainingTrainingRemember – hearing protection is

provided to protect you, if you do not use it, you may lose it

Remember – if in doubt, ask


ObjectivesObjectives What is noise? What is sound? How do we hear? What unit do we use to measure noise? How we get Hearing Loss The Law

– Employer duties– Employee duties

PPE– Where, what and when


Noise at WorkNoise at Work

Thanks for ListeningAny questions

Hansen – managing safely 1 Noise at Work Mark Mallen Group Health and Safety Manager.

Documents

ear slide

noise noise

sound air

eardrum sound

channels sound

sound waves

unwanted sound

middle ear