Workplace Noise Assessment
January 2005
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Do We Need a Survey?
• Can you understand normal speech at 2 m?
(1 m for old regs)
• Has your noise survey meter indicated noise
levels are above the first action level?
• Does your company have a policy of regular
noise surveys?
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Who Should Carry Out the Survey?
A competent person
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What is a Competent Person
• The person should have the following
knowledge and experience
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Purpose of assessment
Understanding of what information to be obtained
Appreciation of their own limitations
How to take measurements
How to record, analyse and explain the results
Care of noise measurement equipment
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Where Do You Start?
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Tour of the factory
Make notes about noisy machines
Ask workers about their work patterns
Are there any machines that are not working
Determine shift patterns
Assess the risk
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Choice of Noise Equipment
• Do we need an integrating SLM?
• Do we need to carry out octave band
analysis?
• Will “C” weighting be required
• Do we need to measure “peak”?
• Do we need dose meters?
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Calibration
• All noise measuring instrumentation must be
calibrated before measurements take place
• Equipment should be calibrated after use
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The Survey
Where to measure
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Close to operators ear
Not too close to affect measurements
Should a tripod be used?
SLM should be held at arms length
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The Survey
How long?
• How long should measurements be?
• Long enough to be representative
• Measure a complete cycle of machine
• Do I need to use a dose meter?
• Are there workers that are transient?
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The Survey
Observations
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How is the noise generated
Does the noise have peculiar characteristics
Could screening be used to reduce noise
Could machines be moved
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The Report
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Introduction
Methodology
Results
Discussion
Recommendations
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Introduction
• Sets the scene
• Details of where the survey was made
• The shift patterns
• Who carried out the survey
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Methodology
• State the methods used
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The equipment used in survey
Serial number of instruments
Calibration
Methods used
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Results
• Results & Calculations
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All the raw data from the survey
Calculations of LEP,d’s
Factual data about machines
Calculation for hearing protection
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Discussions
• Talks about the survey in depth
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Contain factual information on survey
Point out areas where action levels are exceeded
State areas where signs are to be erected
How to silence noisy machines
Ear protectors
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Recommendations
• Review the items contained in discussion
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Final recommendation on how to control noise
Recommend ear protection to be provided
Training to be given
When survey should be repeated
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Case Studies
Noise at Work
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Case 1
• Manufacturer of electrical switchgear
• Various metal work processes
• About 200 employees
• Peak levels of 140 dB exceeded
– due to poor handling of metal sheet
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Case 1
• Hand held sound level meter measurements
– LAeq
– Octave bands
• Personal dose meters
– 12 members of staff
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Case 1
• Less than 80 dB(A)
– Bending machine
– Deburring machine with silencer
– Press
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Case 1
• 80 to 85 dB(A)
– Assembly area
– Hole punch
– Shot blaster
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Case 1
• 85 to 90 dB(A)
– Laser cutter
– Hand deburring
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Case 1
• 90 + dB(A)
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Circular saw
Cross cut saw
Pneumatic riveting
Circular sander
Frame riveting
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Case 1
• Material handling
– staff training
• 2 saws - very high noise levels
– Hearing protection zone (even though
intermittent use)
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Case 1
• Laser cutter
– inherently quiet but noise from material handling
- shaking out
• Belt sander for deburring
– Hearing protection zone
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Case 1
• Shot blaster
– fit attenuator to exhaust
• Hand deburring machine
– 86.5 dB(A) in use - 77.6 dB(A) with
manufacturer’s silencer
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Case 1
• Factory ventilation fans
– remove individual controls
– reduce maximum speed
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Case 1
• Ear plugs were already widely used and
proved suitable for all situations
• Recommended workers in dirty areas should
use ear defenders
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Case 2
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Significant variation of noise levels
Workforce static
Approx. 85 employees in the workforce
7 measurement sessions
6 dose meters
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Case 2
• Result summary for worst affected
LEP,d
Lpeak
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90
130
2
85
130
3
87
135
4
81
126
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Case 2
• Result summary for worst affected
LEP,d
Lpeak
Trumpet
90
130
Viola
85
130
Cello
87
135
Percussion
81
126
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Case 2
• Small curved clear plastic screens
– Dose reduced by 1-3 dB(A)
– Lpeak reduced by 4-5 dB
• Ear plugs
– with flat attenuation properties
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