This document provides an introduction to noise control concepts and methods. It outlines when noise control is required according to legal exposure limits. Key aspects of noise control covered include noise risk assessment, identifying excessive noise exposures, and implementing controls following the hierarchy of control from elimination to administrative controls to personal protective equipment. Engineering controls for noise reduction are discussed in terms of controlling noise at the source, transmission path, and receiver. Methods like insulation, barriers, and enclosure of noise sources are presented. The importance of noise monitoring and a multifaceted approach to noise control following the hierarchy are emphasized.

2. TOPIC 2
INTRODUCTION TO NOISE CONTROL

3. By the end of this session the
participants should be able to:
i. Understand the overall concepts of
noise control
ii.Use noise control methods based
on Hierarchy of Control in order to
improve workplace from noise
hazard.
SESSION
OUTCOMES

4. WHEN THE NOISE CONTROL REQUIRED?
4
Nobody are allowed to exposed over:-
(a) Daily Noise Exposure Level - 85dB(A) / Daily
Personal Noise Dose – 100%
(b) Maximum SPL - 115dB(A) at any time
(c) Peak SPL - 140dB(C)
o If exposed to an excessive noise exceeding
NEL, the employer shall take such measures
to reduce the excessive noise.

5. NOISE RISK ASSESSMENT
5
Area Monitoring Personal Monitoring
Noise mapping (zoning)
Determining noise sources
To measure the worker’s exposure to noise
during his entire work shift. . Every employee
who may be exposed to excessive noise must be
included.
Classifying of SEG
The most exposed employee from each SEG
should be selected for personal monitoring
based on the following selection criteria:
i. work directly with the noise source (tools,
machinery, etc);
ii. work near or pass through areas with noise
exposure;
iii. work in noise area for a long period of time;
Similar
Expose
Groups
(SEG) :
grouping
employees who
have similar
noise exposure
(e.g., perform
the same tasks,
have similar job
functions, or
work in the
same area)

6. REDUCTION OF NOISE EXPOSURE EXCEEDING LIMIT
6
oThe employer shall, before taking the measures, make an
assessment whether it is practicable to reduce such excessive
noise by way of engineering control or administrative control:-
a) It is practicable (Eng. Control) – noise reduction by engineering control
b) It is not practicable (Eng. Control) – noise reduction by engineering and
administrative control
c) It is not practicable (Eng. & Administrative Control) – noise
reduction by administrative control
d) It is not practicable (Administrative Control) – other effective measures
to reduce such noise
oThe employer shall make a report on the assessment, and shall,
upon request in writing from the Director General, give the
Director General a copy of that report within thirty days after
the request is received.

7. KEY ACTIONS OF NOISE CONTROL
7
The key actions for controlling noise will include:
prioritising and tackling the immediate risks
identifying possible methods
assessing the reduction levels that can be
achieved by introducing cumulative controls
assigning responsibilities
monitoring controls and performance.

8. ISO 11690-1
BASIC CONCEPTS IN NOISE CONTROL
To adequately define the noise problem and set a good
basis for the control strategy, the following factors should be
considered:
• type of noise
• noise levels and temporal pattern
• frequency distribution
• noise sources (location, power, directivity)
• noise propagation pathways, through air or through
structure
• room acoustics (reverberation).

9. UTILISING NOISE MAPPING FROM AREA MONITORING
9
 Noise contours will indicate the noise sources
 Noise sources with the higher noise level could be identified and
action to be prioritised
 Priority given to higher machines or process emitting higher noise
levels
Zoning

10. NOISE CONTROL BASIC STRATEGY
10
 Control at source.
 Example - Control at design stage (Prevention through Design (PtD)) , reduction of speed and
pressure.
 Reduction at path
 Example - adding barriers or enclosing the equipment,adding sound-absorbent materials.
 Reduction at receiver
 Example - relocating the employee from the sound field, limiting his working time in the area,
or through the use of hearing protective devices (HPD).

11. OBJECTIVE
SOURCE/PATH/RECEIVER MODEL
Basic treatment strategies using
engineering controls. "Typical"
noise reductions associated with
each strategy are listed below :-
SOURCE
CONTROL
DIRECT PATH
CONTROL
INDIRECT
PATH
CONTROL
RECEIVER
CONTROL
6 to 8 dB
10 to 25 dB &
up
4 to 6 dB
10 to 25 dB &
up
Source: Info@CitySoundproofing.com

12. NOISE CONTROL AT SOURCE
12
The improvement techniques include the
following:
• reduction of impact forces,
• reduction of speed and pressure,
• reduction of frictional resistance,
• isolation of vibrating elements.

13. NOISE CONTROL AT SOURCE…CONT’D
13

14. NOISE CONTROL AT PATH
14
This can be done in several ways:
• to absorb the sound along the path,
• to deflect the sound in some other directions
by placing a reflecting barrier in its path,
• to contain the sound by placing the source
inside a sound-insulating box or enclosure.

15. NOISE CONTROL AT RECEIVER
15
Protecting the Receiver
The following two techniques are commonly
employed
i. Alter work schedule
ii. HPD

16. HIERARCHY OF CONTROL
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Elimination
Substitution
Engineering
Control
Administrative
Control
HPD
Most
Effective
Least
Effective
Noise
Reduction
Exposure
Reduction
Source
Path
receiver

17. PPT-072-01 50
ELIMINATION
17
 Physically removing the hazard
 The most effective hazard control which can be
done by changing a work process in a way that
will get rid of a hazard
• Is the process necessary?
• Can we achieve what we want in a different
way?
• Can we get another option to do it?

18. PPT-072-01 50
SUBSTITUTION
18
 The second most effective way to control a hazards
 Involves removing something that produces a hazard
(similar to elimination), and replacing with something
that does not produce a hazard.
e.g.: substitute quieter process / equipment for noisy ones.
 To be an effective control, the new product must not
produce another hazard.
• ‘Change of process’ – same outcome, different mechanism
• ‘Change of technique’ – same objective – different way of
getting there
• ‘Change of equipment’

19. PPT-072-01 50
SUBSTITUTION…CONT’D
19
http://www.hse.gov.uk/noise
/buy-quiet/index.htm

20. SUBSTITUTION…CONT’D
20
New gen set during purchase
built in silencer (reduce <85dB)
New compressor heatless dryer –no
intermittent purging (reduce <70dB)

21. SUBSTITUTION…CONT’D
21

22. SUBSTITUTION…CONT’D
22
Individual vacuum pump
install at production machine
(40 units) . Noise level (90 dB) Installation of centralize vacuum pump at
facilities plant building complete with noise
absorption material (rockwool with cement
board). Noise level reduce to avg < 70 dB

23. ENGINEERING CONTROL
23
• Engineering controls are defined as: “Methods that reduce noise exposure
by decreasing the amount of noise reaching the employee through
engineering design approaches. Engineering controls isolate the noise
from the worker through noise reduction” (adapted from NIOSH, 1996a).

24. ENGINEERING CONTROL…CONT’D
24
 The next best approach to use when a
hazard cannot be eliminated or a safer
substitute cannot be found.
 Physical changes to the work area or
process that effectively minimize a worker’s
exposure to hazards.
 These controls focus on eliminating or
reducing that actual source of the hazard.

25. PRINCIPLES OF ENGINEERING CONTROL
25
• Absorption
• Insulation
• Distance
• Silencer
• Vibration isolation
• Damping

26. ENGINEERING CONTROL - AT TRANSMISSION PATH
26
DISTANCE is often the cheapest solution. But not effective in reverberant conditions.
Erect A NOISE BARRIER between the noise source and the receiver; in some instances,
a partial barrier can be used.
Once the acoustical barrier is erected, FURTHER treatment, such as the addition of absorbing
material on surfaces facing the noise source, may be necessary
Walls and machine enclosures must be designed to MINIMIZE RESONANCES which will transmit
acoustical energy at the resonant frequency to the protected area
Reduce the REVERBERATION of the room where noise is generated by the introduction of
acoustically absorbent material(s).
o The principles to be observed in carry out engineering control of the noise
transmission path:

27. ADMINISTRATIVE CONTROL
27
• Administrative control is defined as
administrative methods or approaches
that reduce exposure of workers to
noise
• Where engineering control measures
solely is not practicable to comply with
the NEL specified in the Occupational
Safety and Health (Noise Exposure)
Regulations 2019
Administrative controls are defined as:
“Methods that reduce exposure by limiting the time a worker is
exposed to noise through administrative approaches.
Administrative controls isolate the worker from the noise by
reducing exposure” (adapted from NIOSH, 1996a).
• What? • When?

28. ADMINISTRATIVE CONTROL
28
How?
Job rotation
NOISE LEVEL
dB(A)
DAILY EXPOSURE DURATION LIMIT
82 16 hrs
83 12 hrs 42 mins
84 10 hrs 5 mins
85 8 hrs
86 6 hrs 21 mins
87 5 hrs 2 mins
88 4 hrs
89 3 hrs 10 mins
90 2 hrs 31 mins
91 2 hrs
92 1 hr 35 mins
93 1 hr 16 mins
94 1 hr
95 48 mins
Distance
Scheduling
rosters
Quiet areas

29. ADMINISTRATIVE -PROCEDURES & ARRANGEMENTS
29

30. ADMINISTRATIVE PROCEDURES & ARRANGEMENTS
30

31. HEARING PROTECTION
31
• What?
• Personal Hearing Protectors, PHP that
are approved by Director General
• Criteria selection of PHP
• Worker's noise exposure level;
• Hearing ability of the worker;
• Use of other personal protective
equipment;
• Temperature and climate;
• Communication demands on the
worker;
• Physical constraints of the worker or
work activity.

32. HEARING PROTECTION - NOISE REDUCTION RATING (NRR)
32
• Single protection
• For single protection (only ear muffs or ear
plugs are used) use the following formula:
Where;
• LEX,8h is daily noise exposure level;
• 2 is de-rating factor (to lower the rating of a device, especially because
of a deterioration in efficiency or quality).

33. HEARING PROTECTION - NOISE REDUCTION RATING (NRR)
33
• Dual protection
• For dual protection (ear muffs and plugs are
used simultaneously), use the following
formula to determine the Estimated Exposure:
Where;
• NRRh is NRR for the higher rated protector;
• LEX,8h is daily noise exposure level.
Note : Employer may use any recognized method to calculate noise reduction rating such as Single Number Rating (SNR), Sound Level
Conversion (SLC80).

34. HEARING PROTECTION
34
Training on PHP
• Before PHP are issued, the
need for their use shall be fully
explained. Employer shall
provide information and
training to the employees on
the use, fitting, care and
maintenance of hearing
protectors at least once a
year.
Inspection and maintenance
• Employers shall ensure that PHP
are regularly inspected,
maintained, and readily made
available.
• Employees shall also inspect PHP
regularly to detect, and report
damage or deterioration.
• Adequate provision shall be
made for clean storage of PHP
when not in use.

35. HEARING PROTECTION
35
Hearing Protection Zone
• Situations where sign-posting is not
practicable, methods of achieving this
include, but not limited to─
 attaching prominent warning notices to
tools and equipment indicating that PHP
must be worn when operating them;
 providing written and verbal instructions
on how to recognize circumstances in
which PHP are needed; and
 effective supervision of identified
hearing protection zones.
Hearing Protection Zone
• Areas where persons may be exposed to
noise levels exceeding the NEL shall be
sign-posted as 'HEARING PROTECTION
ZONES’, and so far as practicable their
boundaries shall be clearly demarcated
and identified by means of an
appropriate warning sign.
• No person shall enter a hearing
protection zone during normal
operation, unless wearing appropriate
PHP.

36. CONCLUSION
36
• Noise exposure monitoring is essential to determine the needs of noise control.
• Implement noise control based on Hierarchy of Control in order to improve workplace
from noise hazard
• Do not depend solely on HPD

37. TOPIC 3NOISE REDUCTION THROUGH
ENGINEERING CONTROL
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