A Health and Safety Guideline for Your Workplace

Hearing Conservation

Introduction Personal productivity

The risk of noise-induced hearing loss is often If the job involves a lot of communication, hearing
ignored until too late because: impaired workers may quit or transfer to another
position rather than risk criticism or suspicion of
 hearing loss causes no pain. Workers may feel incompetence.
discomfort and pain from excessive noise, but
not from the hearing loss.
Corporate productivity
 the loss can occur gradually, so that exposed
Compensation premiums, surcharges and penalties
workers don’t notice until significant damage
can affect the workplace’s productivity and
has occurred.
financial health.

Once damaged, hearing cannot be restored. Workplaces often contain many sources of noise.
Damaged hearing can affect job performance, Left unchecked, these sources can cause serious
health and productivity harm and easily exceed legal limits. (For more on
legal requirements, see “Legislation.”)
Job performance
Hearing impaired workers may pose a hazard to Many options exist for controlling noise exposure.
others and to themselves. They may misunderstand The best way to protect workers from exposure to
warnings and instructions. excessive noise, and ensure workplaces meet their
legal obligations, is to set up a hearing
Health conservation program.
The effects of hearing loss can include:
 anxiety Components Of A Hearing
 depression Conservation Program
 fatigue A hearing conservation program is a planned,
coordinated course of action implemented to
 withdrawal from social activities
prevent hearing loss. However, effective programs
 poor digestion do more than prevent hearing loss. They can:
 stress  improve employee morale
 poor self-image  create a sense of well-being
 higher blood pressure and heart rate  improve production values, and
 higher cholesterol levels.  reduce the incidence of stress-related disease.
Contents Setting up a program
Hearing conservation programs include: Setting up a program involves:
 engineering controls to minimize the amount  identifying areas in the workplace where high
of sound energy generated noise levels exist
 assessing the levels to which workers are
 administrative controls or procedures for exposed, and
performing specific jobs or tasks  implementing a control program.
 personal protective equipment
 training in the following subjects: Identifying Areas With High Noise
- health effects of noise Levels
- use, care and fit of personal protective Tip: if background noise make it difficult to carry
equipment on a conversation, then the noise levels in that area
- job procedures probably exceed safe limits.
- other program components, as required
Preliminary ways to identify potentially unsafe
 periodic exposure monitoring, and areas include the following:
 audiometric testing.  conducting a walk-through survey
 tapping into others’ experience by:
Program considerations - reviewing journals, books and other
publications on noise, especially those
Appearing below are five considerations for specific to your industry
developing and implementing a hearing
conservation program. - seeking employee input, and
- asking colleagues in similar workplaces to
 Design the program in consultation with joint share insights.
health and safety committees.
Common noise sources
 Develop procedures for workplace monitoring
and employee testing. The main sources of noise in most industries are:
 Add criteria for minimizing noise output to  grinding operations
purchasing policies.  machinery powered by compressed air (air jet
noise)
 Keep records of training, exposure monitoring
and audiometric testing.  fume extraction and ventilation fans
 gears, especially those driving several pieces
 Review the program with the joint health and
of equipment, and
safety committee every year or whenever a
new process or piece of equipment is  tools (e.g., oxy-acetylene welding torches,
introduced. pneumatic nail drivers).

Note: every plant may have additional equipment

or processes that emit noise.

2 š Hearing Conservation
Noise levels by source Assessing Noise Levels
A sample list of noise sources and their With the location of noise sources in hand, you can
corresponding noise levels appears below. assess the level of noise to which workers are
exposed. CSA Standard Z107.56-94 (R1999),
Processes dBA* “Procedures for the Measurement of Occupational
Noise Exposure,” explains how to carry out
air carbon arc cutting 120
measurements, what instruments are needed, and
hammer mill 102 how to interpret results.

punch press 100 Three types of measurements are commonly

carried out:
arc welding 95
 area noise level measurements
large tire curing press 93  personal exposure measurements, and
plastic grinding machine 89  frequency measurement.

laundry facilities 74 Area noise level measurements

office equipment 55 Area measurements indicate the level of noise in
the area at the time the measurement is taken. It
Tools dBA* can only determine exposure if the noise level is
constant, and the exposed worker(s) stays in the
explosive fastening tools 131
area during the entire shift.
table saw 95
Equipment used: a sound level metre.
paint spray gun 91
Personal exposure measurements
*dBA (decibel A scale) is a measurement of sound Personal exposure measurements track exposure to
pressure. (See “Glossary” for more on hearing noise over time (usually eight hours). The
conservation terminology.) measurement is taken by equipment that calculates
the total amount of sound energy received by a
Mapping noise sources microphone.
Once you have identified noise sources, create a
floor plan that shows: Equipment used: a personal dosimeter or an
integrating sound level meter. Personal dosimeters
 equipment and workplace layout
are the preferred choice. Since they are worn by
 areas where noise may be a problem the workers, personal dosimeter measurements
 number of workers in those areas, and better reflect actual exposure.
 noise control measures already in place (for
examples of control measures, see Note: always take more than one personal
“Implementing a Control Program”). exposure measurement, since noise levels often
vary. Guidelines on the number of samples
necessary, according to the accuracy required,
appear in CSA Standard Z107.56-94 (R1999).

Hearing Conservation š 3
Frequency measurement  building noise considerations into the design
Frequency measurement, also known as octave and selection of valves
band analysis, helps in the:  installing more flexible hosing to reduce
hydraulic system noise
 design of noise absorbing enclosures, and
 installing silencers to reduce noise from
 selection of personal protective equipment. pneumatic tools
 installing enclosures around noisy machinery,
This type of measurement is best done by a noise and
consultant, and is not necessary for determining
 installing noise absorbing paneling on walls
exposure.
and ceilings.

Implementing A Control Program (See “Additional Information” for more sources of

Having identified noise sources and calculated information on engineering controls.)
exposure levels, you can now decide what control
methods best suit your workplace. Three options, Administrative controls
in order of preference are: If noise cannot be reduced by engineering controls,
 engineering controls then consider administrative controls to modify
 administrative controls, and how work is performed. These measures include:
 personal protective equipment.  reducing exposure by limiting the time
employees stay in a noisy area
Other elements of a control program include:  performing noisy operations when the least
number of workers are present e.g., during
 employee training, and
lunch or after shifts end
 audiometric testing.
 changing the way in which work is performed,
e.g., minimizing the need to strike items or
Engineering controls drop them into bins
These control measures include:  routine maintenance of equipment, and
 modifying equipment to reduce noise output  rotating workers.
 absorbing the noise before it spreads, and
 changing the frequency of the noise. Note: worker rotation is a controversial option
since it can be seen as merely distributing the risk
Information on noise control measures for specific among workers.
industries is scarce. However, the following
measures apply to many pieces of equipment and Personal protective equipment
many industry sectors: If noise cannot be reduced by engineering controls
 using helical or other low noise gearing to or administrative methods, then provide personal
reduce noise protective equipment (PPE) and related training
 using anti-vibration mounts and flexible drive (see “Training”). PPE can reduce the amount of
couplings to prevent transmission of noise noise reaching the ear by 8-15 dB.
from one part to another
 mounting motors and pumps on anti-vibration
mounts

4 š Hearing Conservation
Note: the actual reduction in exposure provided by Common training topics include:
PPE can vary from manufacturers’ claims. Factors  health effects of noise
affecting the amount of protection provided  control measures in place to reduce noise
include: exposure
 how long the protection is worn  reasons for audiometric testing, plus the
 how well it fits confidentiality of testing results, and
 the material of construction, and  proper fit, use and care of PPE.
 the frequency of the noise. Low frequency Note: use examples and situations that apply to
noise causes PPE to vibrate and transmit the your workplace.
sound to the ear.
Audiometric testing
Selecting hearing protectors
Ongoing audiometric testing helps to ensure your
The table below indicates the class of hearing program is effective. Testing and analysis can
protector required for specific noise levels.* identify why hearing loss has occurred, and how to
Ensure that the protector is suitable for the noise prevent further loss. If the testing is being
level and noise frequency. conducted by a consulting firm, provide the firm
with exposure data and information on control
Maximum Equivalent Recommended Class measures in place.
Noise Level, dBA of Hearing Protector
Testing considerations
Leq** less than 85 No protection required Timing – Test employees before they start
dBA working in a noisy area to set a benchmark for later
tests. Then conduct periodic testing at least
Leq up to 89 dBA Class C annually.
Leq up to 95 dBA Class B
Accuracy – The following considerations help
Leq up to 105 dBA Class A ensure accurate results:
 the tester must be qualified to conduct
Leq up to 110 dBA Class A plug + Class audiometric tests
A or Class B muff  tests must take place in a controlled
environment, preferably a testing booth
Leq more than 110 Class A plug + Class
dBA A or Class B muff and  the instruments must be calibrated to ensure
limited exposure accuracy
 the results must be evaluated – either by
* Source: CSA Standard Z94.2-94, Hearing Protectors. examining individual audiograms, or by
** Leq is an average level of noise calculated from analyzing the results of a group of audiograms
measurements of noise that varies over time. – using audiometric data base analytical
techniques, and
Training  the participating employees must understand
Training helps to ensure that workers benefit from the importance of these tests.
and support the controls implemented, especially
PPE. Conduct a training needs assessment to Discuss with prospective audiometric testing firms
determine what content and level of training are how they will meet the first four conditions.
most suitable for your employees. However, your workplace is responsible for
the fifth.

Hearing Conservation š 5
Periodic exposure monitoring Note: the noise exposure limits in Section 139 are
Periodic monitoring of employee exposure can considered minimum performance requirements,
help indicate deficiencies in engineering and and may change. Eventually, new legislation may
administrative controls, and reveal problems before require Ontario workplaces to meet lower levels of
they appear in audiometric test results. exposure, and to establish hearing conservation
programs. Lower limits have already been set
Timing – Monitor exposure at least once a year or elsewhere (see “Comparison of Noise Exposure
whenever a new process or piece of equipment Limits”).
is introduced.
Standards
Legislation Canadian Standards International, formerly the
Canadian Standards Association, has developed
Section 139, O. Reg. 851 many standards related to noise. These standards
Specific requirements regarding noise exposure list the procedures, required instruments and
appear in Section 139 of Ontario Regulation 851 method of analyzing measurements. A list of
(Industrial Establishments) under the Occupational standards appears in “Additional Information”.
Health and Safety Act. For example, this section
sets maximum noise exposure levels for various Additional Information
time periods (see “Daily Exposure Limits”). Where
workers are exposed to a sound level of 90 dBA or The following is a list of sources that can provide
greater, the section also requires the following: further information.
 that measures be taken to reduce noise levels
below the set limit Publications
 if not practicable, that exposure be limited or
 Noise and Hearing Conservation Manual, ed.
hearing protection be provided and worn, and
E.H. Berger, W.D. Ward, J.C. Morrill, L.H.
 that signs be posted in areas where noise levels
Royster.
exceed the eight-hour daily maximum 90 dBA.
 Noise Control – A Guide for Employers and
Daily Exposure Limits* Employees, IAPA Publication
Sound Level Duration  OHS Canada Annual Buyers Guide
(decibels) (hours per 24 hr day)
90 8 Standards
92 6  CSA Standard Z94.2-02, “Hearing Protectors”
95 4  CSA Standard Z107.4-M86, “Pure Tone Air
Conduction Audiometers for Hearing
97 3
Conservation and for Screening”
100 2  CSA Standard Z107.51.M1980 (R1999),
102 1½ “Procedure for In-situ Measurement of Noise
105 1
from Industrial Equipment”
 CSA Standard Z107.53-M1982 (R1999),
110 ½
“Procedure for Performing a Survey of Sound
115 ¼ or less due to Industrial, Institutional or Commercial
over 115 no exposure Activities”
* Source: (Safety, Health & the Law Software: The
Occupational Health & Safety Act and Industrial
Regulations)

6 š Hearing Conservation
 CSA Standard Z107.56-94, “Procedures for the These numbers are developed in ideal laboratory
Measurement of Occupational Noise conditions and may not represent the true
Exposure” attenuation of the hearing protection device when
 CSA Standard Z107.6-M90, “Pure Tone Air worn by a worker, due to variability in exact fit,
Conduction” imperfect seal due to movement of jaw or
perspiration, deterioration of device over time, and
Websites does not account for any modification made by the
 www.ccohs.ca (Canadian Centre for wearer. The Occupational Safety and Health
Occupational Health and Safety) Administration in the United States uses the
 www.acgih.org (American Conference of following guideline for adjusting the published
Governmental Industrial Hygienists) NRRs and derating them by 50%.
 www.gov.on.ca/LAB/leg/lege.htm (Ontario
Noise – unwanted sound that causes harm, either
Ministry of Labour)
by causing hearing loss or stress, or interferes with
communication.
Glossary
Sound energy – the amount of energy transmitted
dB (decibel) – a measurement of sound pressure to the ear by noise.
where 0 dB is defined as being the faintest sound
that a person with normal hearing can hear. This Sound pressure – the fluctuations in air pressure
measurement scale is not additive. For example, an caused by noise. The louder the noise, the greater
increase from 10 to 20 dB does not mean that the the changes in air pressure. These fluctuations
sound pressure has doubled. Instead, it means that cause the ear drum to vibrate.
the sound pressure has increased by a factor of 10.
Comparison Of Noise Exposure
dBA (decibel A scale) – a measurement of sound
pressure that has been modified to take into Limits
account that the ear is not equally sensitive to all
frequencies. MOL Duration of ACGIH
Sound Level in exposure Sound Level in
Impact noise or impulsive noise – a noise of short dBA (hours) dBA
over a 24
duration where the sound pressure level rises very
hour period
rapidly to a peak and decays to background level
(i.e., hammering metal plate, nail gun). 80 24 75

Leq (average equivalent noise level) – an average 85 16 82

level of noise calculated from measurements of 90 (5dB 8 85 (3dB
noise that varies over time. exchange rate) exchange rate)

NRR (Noise Reduction Rating) – a single number 95 4 88

representing the attenuation value for a given 100 2 91
hearing protection device (i.e., ear plug, ear muff,
etc.). 105 1 94
110 .5 97
115 < or = 0.25 100
no exposure etc.
over 115

Hearing Conservation š 7
Refer to the appropriate document for further © INDUSTRIAL ACCIDENT PREVENTION
details and explanation. MOL – Reg. 851– ASSOCIATION, 2001, 2005. All rights reserved.
Industrial Establishments made under the As part of IAPA's mission to inform and educate, IAPA
Occupational Health and Safety Act. ACGHI – permits users to reproduce this material for their own internal
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other limits exist for impact noise exposures. recorded, or otherwise, without the express prior written
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For further information, refer to the following
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be assumed that all acceptable safety measures are contained
in this material or that additional measures may not be
required in the conditions or circumstances that are applicable
to the user or his/her organization, and that the user will
personally make his/her own assessment of the information
contained in this material.

While IAPA does not undertake to provide a revision service

or guarantee accuracy, we shall be pleased to respond to your
individual requests for information.

Revised: March 2005

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