1. Mark Mallen Group Health and Safety Manager
Noise at Work
Mark Mallen
Group Health and Safety Manager
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2. Introduction Noise at work and how it can affect you
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3. 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
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4. 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
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5. 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!
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6. What is Noise? Effects Short term Long term Annoy Distract Deafness
Tinnitus
Noise Induced Hearing Loss (NIHL)
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7. Sound 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
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8. Sound Like ripples on a pond – sound pressure wave
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9. Sound A Sound Wave created by a vibrating object: The vocal chords
A guitar string
A machine
Traffic
The diaphragm of a radio speaker
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10. Sound 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 second
The unit of frequency is the hertz (abbreviated Hz), where:
1 Hertz = 1 vibration/second
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11. Sound The human ear detects Any sound less than 20 Hz
Ranges between approximately 20 Hz to Hz
Any sound less than 20 Hz
Infrasound
Any sound above Hz
Ultrasound
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12. How do we hear Sound? The Ear The outer ear The middle 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.
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13. The Ear
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14. The Outer Ear Consists of an earflap and an ear canal
The earflap protects the middle ear and eardrum
It also channels sound waves to the eardrum
Sound is still a sound pressure wave
At the eardrum, the wave converts into vibrations
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15. The Middle Ear An 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
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16. The 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
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17. The 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
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18. The Ear
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19. The Cochlea Snail-shaped organ
Lined with over 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
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20. The 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)
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21. The 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 times more intense, is assigned a sound level of 40 db.
This scale is based on powers or multiples of 10
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22. Typical Noise Levels
Source
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
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23. Hearing 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
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24. Noise Induced Hearing Loss
Chronic NIHL
Damage is caused to the sensitive cells in the cochlea
Occurs gradually from exposure to less intense noise levels
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25. Noise 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
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26. Noise 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
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27. Noise 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
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28. Noise Induced Hearing Loss
An ‘normal’ audiogram
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29. Noise 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
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30. Noise Induced Hearing Loss
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
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31. The 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 Pascals or 140dB
The sound at the ear is represented by (A)
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32. The 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 Pascals or 140dB
This relates to sudden noise
the duties are similar to those required by the second action level
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33. The Law Employers duties Between the first and second action levels
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
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34. The 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
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35. The Law Employees duties Use any other equipment the employer provides
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
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36. 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
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37. Information, Instruction, And Training
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
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38. Exposure areas
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39. Exposure areas
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40. Information, Instruction, And Training
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
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41. Information, Instruction, And Training
Duties 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
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42. Information, instruction, and training
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.
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43. Information, Instruction, And Training
Earmuffs
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44. Information, Instruction, And Training
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
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45. Information, Instruction, And Training
Earplugs
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46. Information, Instruction, And Training
Remember – hearing protection is provided to protect you, if you do not use it, you may lose it
Remember – if in doubt, ask
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47. Objectives 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
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48. Noise at Work Thanks for Listening Any questions
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