Real world use and performance of hearing protection

Real world use and performance of hearing protection
Health and Safety
Executive
Real world use and performance
of hearing protection
Prepared by Health and Safety Laboratory
for the Health and Safety Executive 2009
RR720
Research Report
Health and Safety
Executive
Real world use and performance
of hearing protection
Liz Brueck BSc, MIOA
Health and Safety Laboratory
Harpur Hill
Buxton
Derbyshire
SK17 9JN
This report considers the effectiveness of hearing protectors in everyday work situations. The study
reported here was undertaken in two parts. The first consisted of interviews with employers to discuss
management of noise and hearing protector use, and on site observation of hearing protector use. The
purpose of these visits was to see:
n
n
n
n
how well hearing protection was used;
the training provided;
the use of other PPE and equipment that may limit attenuation;
behavioural factors affecting use, taking into account the noise exposure of employees and the
environment in which the hearing protection is worn.
The second part was objective laboratory measurements of hearing protector insertion loss. The purpose
of these measurements was to quantify the reduction in protection due to poor fitting or maintenance for
a range of hearing protectors. Earmuffs were tested using the MIRE (microphone in real ear) method while
earplug insertion loss was measured using a head and torso simulator with a simulated pinna and ear
canal.
This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents,
including any opinions and/or conclusions expressed, are those of the author alone and do not necessarily
reflect HSE policy.
HSE Books
© Crown copyright 2009
First published 2009
All rights reserved. No part of this publication may be
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Applications for reproduction should be made in writing to:
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or by e-mail to [email protected]
ii
CONTENTS
1
INTRODUCTION......................................................................................... 5
2 METHOD FOR EMPLOYER INTERVIEWS AND OBSERVATION OF
HEARING PROTECTOR USE ........................................................................... 6
3 ANALYSIS OF INTERVIEWS AND OBSERVATIONS............................. 10
3.1
Choice of hearing protection.................................................................. 10
3.2
Use of hearing protection....................................................................... 14
4 LABORATORY TESTS OF EARMUFF INSERTION LOSS..................... 21
4.1
MIRE insertion loss test method ............................................................ 21
4.2
Earmuffs selected for testing ................................................................. 21
4.3
Testing earmuffs worn with other PPE and clothing .............................. 22
4.4
Testing earmuffs in different conditions and orientations....................... 22
4.5
Earmuff performance results ................................................................. 25
5 LABORATORY TESTS OF EARPLUG INSERTION LOSS..................... 35
5.1
Insertion loss test method for earplugs .................................................. 35
5.2
Earplugs selected for testing ................................................................. 35
5.3
Comparison of results for an ear simulator and human subjects ........... 35
6 QUANTIFYING THE EFFECTIVENESS OF HEARING PROTECTION
SEEN IN USE................................................................................................... 37
6.1
Ineffective use of hearing protection ...................................................... 37
6.2
Under protection .................................................................................... 38
7 CONCLUSIONS........................................................................................ 40
7.1
Workers receiving no protection ............................................................ 40
7.2
Workers using hearing protection when not required ............................ 40
7.3
Provision of hearing protection .............................................................. 41
7.4
Choice of hearing protection.................................................................. 41
7.5
Real world attenuation of hearing protection ......................................... 42
8
RECOMMENDATIONS............................................................................. 44
9
REFERENCES.......................................................................................... 45
10
10.1
10.2
10.3
10.4
10.5
10.6
10.7
10.8
APPENDIX A - INDIVIDUAL PREMISES VISITED............................... 46
Vehicle component manufacturer .......................................................... 46
Metal fabricated buildings manufacturer ................................................ 48
Bottling plant.......................................................................................... 50
Vehicle servicing and repair centre........................................................ 51
Specialist Joinery workshop .................................................................. 53
Vehicle accident repair centre ............................................................... 55
Ironwork restorer and manufacturer....................................................... 56
Printers .................................................................................................. 57
-1-
10.9
10.10
10.11
10.12
10.13
10.14
10.15
10.16
Confectionary manufacturer .................................................................. 58
Joinery factory ....................................................................................... 59
Manufacturer of small plant machinery .................................................. 61
Sheet metal workshop ........................................................................... 63
County Council ...................................................................................... 64
Pressure system component manufacture ............................................ 65
Cement works........................................................................................ 66
Outdoor workers – Random encounters ................................................ 67
-2-
EXECUTIVE SUMMARY
Objectives
Hearing protection effectiveness is normally estimated from laboratory test data. HSE
requested the Health and Safety Laboratory consider the effectiveness of hearing protectors in
everyday work situations. This study was undertaken in two parts. The first consisted of
interviews with employers to discuss management of noise and hearing protector use, and onsite observation of hearing protector use. The second part was objective laboratory
measurements of hearing protector attenuation to quantify the attenuation lost due to factors
including poor fitting or maintenance.
Main Findings
Three of the twelve companies that allowed on site observation of hearing protector use during
normal working, and one out of four groups of outdoor workers seen had problems with
ensuring correct use such that the hearing protection use was ineffective (nil protection) for all
or the majority of workers. In addition in premises where the majority of workers were seen
making effective use of hearing protection one in seven workers were still seen to be not using
hearing protection when and where its use was required. This proportion suggests that possibly
only 60% of workers supposedly using hearing protection are in fact protected.
Reduced audibility was a common reason given by users for not wearing hearing protection.
None of the employers seen were aware of the availability and benefits of flat response,
communication and sound restoration hearing protectors.
Hearing protection was also seen in use where there was no risk. One employer had set an
entire building as a hearing protection zone even though quiet areas work areas were included.
Another employer also considered he should issue hearing protection as a blanket measure
rather than assessing the actual risk.
All employers visited by appointment were providing hearing protection of a suitable type for
the work environment and compatible with other personal protective equipment (PPE) worn.
Hearing protection was visibly in a good condition apart from extremely dilapidated earmuffs
that were the only protection supplied by one employer. In two out of four unplanned
encounters with outdoor workers earmuffs were worn over clothing or other PPE that would
have resulted in reduced attenuation.
Less than half of employers supplied hearing protection as part of a comprehensive noise
control programme or selected hearing protection according to the attenuation required. As a
consequence most heavy-duty hearing protection used would be predicted to provide too much
protection (over protect). Only two workers were seen wearing hearing protection predicted to
provide insufficient protection (under protect) according to the manufacturers’ data.
Employers requiring earplugs with metal tracers were unable to source mid or low attenuation
devices. Available earplugs containing tracers all provided high attenuation
80% of the employers visited provided some training on the use of the hearing protection
provided. One group of outdoor workers had also received training. The type of training varied
from simply the provision of written instructions to hands-on training in small groups.
-3-
Compressible foam earplugs were poorly fitted by just over half of the users seen. Most users
were unaware of how to compress the earplug before fitting. Laboratory tests showed
incorrectly compressed earplugs may not fill the ear canal when fitted resulting in a measured
SNR of 9dB or less. Moulded or foam push in type earplugs were said by users to be easier to
fit and were generally observed to be well fitted.
Laboratory tests showed earmuffs deteriorate with use due to reduced headband tension likely to
result in under protection in some real world conditions without obvious visible deterioration of
the earmuff.
RECOMMENDATIONS
Hearing protection is often considered as the first and only solution where a noise risk exists.
Users need to be aware that it is not a simple or reliable solution.
Most employers did not select hearing protection according to the attenuation required. It
would be beneficial if information on the approximate upper and lower sound levels for which
the protector is likely to be suitable was included on the hearing protector packaging and with
any advertising. The information could take account of likely real world attenuation. This
information could be provided in addition to the attenuation data currently provided.
A maximum lifetime, in terms of approximate duration of use, should be provided for all
reusable hearing protection. Hearing protector attenuation deteriorates with use and this
deterioration may not be apparent to the user.
Compressible foam earplugs are generally poorly fitted, as users are generally unaware of how
these should be compressed before fitting, or unaware of the importance of correct compression.
An incorrectly compressed earplug may give virtually no attenuation. Correct use requires a
high level of training, supervision and motivation. Employers providing this type of protection,
and users, need to be aware of these potential problems, and of the existence of alternative types
of earplug such as the foam push-to-fit type.
There needs to be greater awareness of the types of protectors that can assist audibility and
communication.
Earplugs with tracers are required in a wider range of attenuation than is currently available.
There is a need for clothing compatible with correct earmuff fitting for outdoor workers.
Earmuffs worn over conventional hats and hoods can only provide limited attenuation.
-4-
1
INTRODUCTION
This report considers the effectiveness of hearing protectors in everyday work situations. The
study reported here was undertaken in two parts. The first consisted of interviews with
employers to discuss management of noise and hearing protector use, and on site observation of
hearing protector use. The purpose of these visits was to see:
How well hearing protection was used;
The training provided;
The use of other PPE and equipment that may limit attenuation;
Behavioural factors affecting use, taking into account the noise exposure of employees
and the environment in which the hearing protection is worn.
The second part was objective laboratory measurements of hearing protector insertion loss. The
purpose of these measurements was to quantify the reduction in protection due to poor fitting or
maintenance for a range of hearing protectors. Earmuffs were tested using the MIRE
(microphone in real ear) method while earplug insertion loss was measured using a head and
torso simulator with a simulated pinna and ear canal.
-5-
2
METHOD FOR EMPLOYER INTERVIEWS AND
OBSERVATION OF HEARING PROTECTOR USE
Employers were contacted by telephone and asked if they used hearing protection, and if they
would be willing to help with this study. Fifteen employers agreed to help, and all of these were
interviewed on hearing protector use at their premises. Out of these fifteen, thirteen gave access
to working areas to observe hearing protector use. Of the two who did not allow access: one
only had dispersed outdoor teams using hearing protection, and one could not allow access for
hygiene reasons.
The participating employers consisted of four small premises with no more than 10 staff
working in noisy areas, six medium size employers with no more than 100 staff on site and five
employers with more than 100 employees on site. The premises are listed in Table 1.
Interviews were arranged by appointment with a manager or safety officer. In some cases they
were able to provide their noise risk assessments or safety files for additional information
during the interview.
The following topics were considered during the interviews:
Choice of hearing protection
Factors considered in hearing protector choice
The availability of the hearing protection
Other head-worn clothing and PPE used with hearing protection
Problems associated with hearing protector use
The training and consultation of staff on noise hazards and hearing protection use
Maintenance of correct hearing protector use
Other noise controls
Results of health surveillance if used
Where possible a visit was made to noisy working areas after the interview. These visits were
normally accompanied by the person seen in the interview or by a works supervisor. Hearing
protector use was checked visually, noting the type, how well it was fitted, and how consistently
it was used. Checks of noise levels in work areas were also made. Where possible individual
employees gave their views on hearing protector use, but in some premises employees were
reluctant to speak about this.
In addition to these planned visits to employers, four unplanned encounters with outdoor
workers seen using earmuffs are included in this report.
-6-
Table 1 Summary of hearing protection and conditions at premises visited and for outdoor workers seen
Full site visit details are provided in an appendix at the end of this report. References to the relevant appendix subsections are given in the table.
Note – the single number rating (SNR) value is provided for all CE marked hearing protectors (HP). The manufacturer’s quoted SNR values are shown
in the table below. The SNR provides a simple estimate of the protection when corrected for the frequency content of the noise.
Appendix Site
HP and PPE available
SNR
HP fit/ condition
9.1
Neckband earmuff
Over head earmuff
Foam earplug
Flanged earplug
Flanged earplug
Custom moulded
31
30
37
25
30
Variable
Not seen
1 well fitted
3 poor, 1 well fitted
Not seen
Not seen
5 well fitted
3 no HP
Vehicle brake manufacturer
650 employees
50 to 60 working in >85dBA each day
150 to 200 with custom moulded earplugs
Sound level
where HP
used dBA
Availablity
Maintenance
With induction
Earplug dispensors
Earmuffs on request
Custom moulded
where HP compulsory
Custom moulded serviced annually
No NIHL reported
70 staff on Dupont Stop Oberservation programme
Radios or personal stereos banned
hearing protection zones where >85dB(A)
Whole area hearing protector zone
Radios still to be dealt with
Noise assessment made
Training
91
86 to 91
Health Surveillance
85 to 90
86 to 87
9.2
Metal fabricated buildings manufacturer
Employs 40 in factory, 10 outside
Banded earplugs
Flange earplug + visor
Flange earplug
Custom moulded + visor
Foam earplug
Over head earmuff
23
30
30
23
33
27
Not seen
3 well fitted
4 well fitted
4 well fitted
1 poor fit
3 well fitted
82
95
82
106
81
81 to 82
Training within last month
in groups of about 6
noise control
fitting
care of HP
Custom moulded to all staff
earplug dispensors
9.3
Bottling plant (plastic bottles only)
80 staff working shifts
Working 4 x 12 hour days every 8 days
No hygiene restriction on choice of HP
Foam corded earplug
Foam corded earplug
Earmuffs (engineers)
Hair nets and hoods worn
34
35
Unknown
HP not required due to
plant shut down
<75
85 to 90
when running
With induction
Dispensors and hand washing > 85dB HP zones
at entrances
Shift leaders do daily safety checks
Regular safety audits
Only fork lift drivers
No details
9.4
Vehicle servicing and repair centre
10 staff seen
8.5 hour day
Over head earmuffs with goggles 26
With induction plus
written instructions
Said by safety officer to
be ineffective
None
Body shop staff only
NIHL reported
37
Only seen used after
95 to 98
instructed by safety officer when using
User unable to fit
power tools
New earmuffs on show but
not enough to go round
Foam earplugs with respirator
9.5
Joinery workshop
4 employees
8 hour working day
Two pairs of broken earmuffs
shared between staff
Unknown
Ineffective due to
severe damage
None
No replacement HP
None
None
9.6
Vehicle accident repair centre
10 employees in workshop
Foam earplug
Overhead earmuffs
Visors, goggles, and safety
glasses also used
28
27
Moderate fit
Bgd 72
Not seen in use/ moderate HP used with
condition
power tools
External safety training on
PPE and safe use of tools
Earplug dispensers
Personal issue of earmuffs
PPE checked every month
Tools requiring HP identified
Purchasing quiet tools
6 monthly health and safety meeting
Aware problems getting staff to use protectors
All staff
No NIHL reported
9.7
Iron work restoration
19 employees on shop floor
Overhead earmuff
Overhead earmuff
Foam earplug
Helmets with integral earmuffs
used off site
Eye protection also used
27
24
28
1 poor fit
Not seen
1 moderate fit
Not seen
With induction
including when and why
HP required
Personal issue of earmuffs
Staff had supply of earplugs
Registar of issue, regular replacement procedure
Buying quiet tools
None
85 to 91
when using
machines
Bgd 76 to 78
HP used with
power tools
-7-
Just started
No results yet
Table 1 (continued) Summary of premises visited and outdoor workers seen
Appendix Site
HP and PPE available
SNR
HP fit/ condition
Sound level
where HP
used dBA
9.8
Printers
6 employees seen in print room
Overhead earmuff
Foam earplug
25
36
1 poor fit
81 to 83
9.9
Confectionary manufacture
Over 600 employees
Earmuffs used by engineers
Foam earplug
Foam earplug
Unknown
32
36
9.10
Joinery factory
82 employees
Overhead earmuffs
Foam earplug with rigid centre
Flanged earplug
Use earmuff covers when hot
and sweaty
30
23
30
Foam earplug with rigid centre
Foam earplug with rigid centre
Foam earplug
Flange earplug
29
27
28
30
None seen
3 good, 2 poor fit
2 poor fit
2 moderate fit
Foam earplug with rigid centre
Foam earplug with rigid centre
29
27
28
30
35
28
None seen
84 to 92
7 moderate to good fit and 84 to 92
2 poor fit
2 good fit
84 to 92
2 good fit
84 to 92
10
84 to 92
2 good fit
80 to 85
Good condition not in use
Not seen in use
9.11
Small plant manufacturer
125 on shop floor, 95 in noisy areas
Availablity
Maintenance
Health Surveillance
Personal issue of earmuffs
Supply of earplugs
Signs on machines
None
No access to factory area <80 to 95
Training on induction
Not seen
Not seen
None
Well fitted
Poor or deliberate misfit
Moderate to well fitted
85 to 100
Training on use of HP when Foam earplugs at entrance
first provided, risks explained
around factory
Ineffective - most users wearing foam earplugs in
outer ear outside ear canal
None
73 to 75
73 to 75
73 to 75
73 to 75
Induction, and ext consult
ant runs training every 2
months
Risk assessments for all
work
Earplug dispensers at entranceMonthly safety audits by external facilitator
for foam plug with rigid centre
and EAR classic
No training. Staff said
they knew how to use
hearing protection
From workshop office
90% with HP
9.12
Small sheet metal workshop
4 to 5 staff on shop floor
Foam earplug
Flange earplug
No hearing protection
Foam earplugs with rigid handle
Earmuffs
9.13
Local Authority (office interview)
Countryside service (chainsaws, brush
cutters and strimmers)
Combination visor, helmet and
earmuffs
Unknown
Highway maintenance
Earmuffs
EAR banded
26
23
Pressure system component manufacture
Hot pressing
Machining
putting together
3 shift system 24 hour operation
Earmuffs
Flanged earplug
Foam
27
30
28
9.14
Training
No training
All using earmuffs or
earplugs well fitted
Policy to buy low vibration tools
No noise policy
Said supervision on site is weakest link
Audibility a problem esp. highway maintenance
Training demos
on how to fit
All road workers trained
in last 12 months
Planning 1 week induction
training for new road workers
Looking at refresher
83 to 98
Induction
Use printed instructions
for fitting
No checking of actual fit or
hands on training
-8-
No dispensers seen
HP zones clearly marked
Just started for 85%
of workers
Voluntary in last 3 years
plus referral where cause
of concern (eg claim)
NIHL found
Table 1 (continued) Summary of premises visited and outdoor workers seen
9.15
9.16
Site
HP and PPE available
SNR
HP fit/ condition
Sound level
where HP
used dBA
Cement works
150 on site including contractors
Problem with both noise and dust
Foam earplug
Flanged earplug
Custom moulded (on trial)
Foam earplug with rigid stalk
Earmuff helmet mounted
Earmuff helmet mounted
Eye protection, dust masks,
hard hats also worn on site
28
28
38
30
34
Unseen
Unseen
Unseen
Unseen
Unseen
Good fit, dusty condition
89 to 94
Grounds maintenance
Strimming
Helmet, visor and earmuff
combination
Unknown
Good fit and condition
95
Grass cutting, mower and strimmer
self employeed gardener
Optime III over head
35
Good fit and condition
90 to 95
Advice from health and
d)
safety advisor (personal friend)
Community punishment team
Unidentified overhead earmuff
for wearing with visor
Unknown
Good condition, not used
95 (subjective
estimate)
Road maintenance
2 workers
private contractor
Earmuffs over cap, jacket
hood. and eye protection
23
97
Earmuffs over fleece hat
mask, eye protection
31
Poor fit and condition,
seals cracked, no band
tension
Good condition, poor fit
Initial safety training provided Onlyonepair availablefor 3 Earmuffs weresharedandnot issuedtoindividuals. None
workers usingstrimmers
Teammembers hygieneconcerns preventeduse
but wereconsideredunimportant bymanagement
Noalternativeprotectors
Noneknowntoworkersseen
No training
available
Training
Availablity
Foamearplugdispensors
Induction
at entrances tonoisyareas
Tool box talks every 6 months
Don't actually show users
how to fit
Maintenance
HealthSurveillance
Supervisorsandcolleageswill check onhearing
protection
Managers andsupervisorshave
additional safetytraining
Just startedthisyear
NIHLfound
Outdoor workers
107
-9-
3
3.1
ANALYSIS OF INTERVIEWS AND OBSERVATIONS
CHOICE OF HEARING PROTECTION
Compressible foam, push in foam, flanged, and custom moulded earplugs were seen in use.
Earmuffs seen were either headband or helmet mounted types. Employers also reported
providing neckband earmuffs and banded earplugs or ear canal caps but none of these were seen
in use. No specialist flat-response, sound restoration, or communication hearing protection was
provided at any site visited.
3.1.1
Choice and compatibility with other personal protective equipment
(PPE)
Where the need for hearing protection is occasional or intermittent earmuffs are generally more
suited because they can be removed and fitted easily. Earmuffs were available at all workplaces
where hearing protection was required for the occasional use of noisy tools, with one exception.
This exception was the manufacturer of small plant machinery where only earplugs were
available.
During planned visits earmuffs were occasionally seen worn with goggles or safety glasses but
where more intrusive PPE was worn such as visors and helmets, earplugs or helmet-mounted
earmuffs were used.
In the unplanned encounter with a community punishment team the earmuffs provided were
incompatible with the face visors they used. No alternative protectors were available.
In summary:
Most employers were providing hearing protection that is compatible with the nature of
the work and other head worn PPE.
Earmuffs were once seen used over other PPE that would compromise the effectiveness
of the protection.
3.1.2
Choice and environmental factors
The confectionary manufacturer reported that the hot, dusty environment made hearing
protector use difficult and uncomfortable. Dusty and hot conditions also existed at the cement
works. In both premises it was said earplugs were generally preferred because earmuffs were
difficult to keep clean and comfortable.
Hygiene was the main factor affecting choice of hearing protection at the confectionary
manufacturer. Disposable, corded earplugs were used that included metal tracers. The metal
tracers can be detected should the earplugs enter food products. The chosen earplugs potentially
provided overprotection: that is unnecessarily high protection and hearing impairment. The
employer had not been able to find lower attenuation earplugs with tracers. This limited
availability was later confirmed by a web search.
Another alternative sought by the confectionary manufacturer was banded earplugs. However
only bands with detachable plugs were known to be available, and these had the potential to
enter the confectionary products. Fixed, banded earplugs had not been found.
- 10 -
Compressible foam plugs were available at 11 out of the 15 premises visited. These require
compression by rolling before insertion into the ear but few places visited were aware of the
need to use them with clean hands. The bottling plant did provide hand-washing facilities by
the earplug dispensers but no similar hand-washing facilities were seen at the other sites visited.
Outdoors workers were only seen using earmuffs. Road maintenance workers were seen on a
cold day using earmuffs over hats and hoods. No alternative protectors, or compatible clothing
was available to them.
In summary:
Hot or dusty conditions were reported to make earmuff use difficult and uncomfortable.
Awareness of the need to fit earplugs with clean hands was not widespread. Only one
premises provided hand-washing facilities by earplug dispensers.
Earmuffs are likely to be worn over clothing in cold conditions. Although integral
earmuffs are available for use with head worn PPE, specific compatible clothing is not
generally available.
3.1.3
Choice provided to employees
A choice of hearing protectors is important so that users can select a protector that fits them and
is comfortable. As some users have difficulty inserting earplugs, and earplugs are not suitable
for someone suffering from an ear infection, a choice including both earplugs and earmuffs is
preferred.
Out of the fifteen employers visited:
Two provided no choice – The small joinery workshop had only two pairs of damaged
earmuffs to share between four workers. A vehicle servicing and repair centre had
provided one type of earmuff for general use, and one type of earplug for use by the
paint spray operator.
Three provided earplugs only – For hygiene reasons a confectionary manufacturer
and a bottling plant only allowed the use of disposable earplugs for staff working on
production. The manufacturer of small plant machinery provided a choice of four types
of earplug but no earmuffs.
Six provided a choice of three or more protectors including both earmuffs and
earplugs.
All those using hearing protection with helmets provided helmet-mounted
protectors – Three employers required hearing protection to be used with a helmet. All
three provided helmet-mounted protectors; one employer provided a choice of two
helmet-mounted protectors.
In summary:
Employers are able to provide a choice of hearing protection.
Choice may be limited by hygiene requirements, and compatibility with other PPE.
Two small employers provided no choice and were unaware of any need to do so.
- 11 -
3.1.4
Selection according to attenuation required
As a pragmatic means of ensuring noise exposure is less than 85dB and in accordance with the
recommendations in EN 458:2004 for the selection of hearing protection HSE’s guidance to the
Control of Noise at Work Regulations states that hearing protection should be selected that will
reduce the A-weighted level at the wearer’s ear to between 70 and 85dB. Where levels are
reduced below 70dB the user will be overprotected and experience an unnecessary hearing
impairment that also has safety risks.
Out of the 15 employers:
Four had selected hearing protection according to the attenuation. These were all
medium to large employers; the metal fabricated buildings manufacturer, the large
joinery factory, the county council, and the cement works. The metal fabricated
buildings manufacturer and the cement works had used the HSE calculator, the large
joinery factory had used the services of a hearing protector manufacturer to survey the
factory and prescribe suitable protection. The local authority used standard selection
methods and had chosen hearing protection for road workers with low attenuation to
allow maximum audibility of moving traffic.
Five considered the attenuation had been a factor in the choice. These were small
to large employers: the vehicle component manufacturer, the accident repair centre, the
ironwork restorer, the manufacturer of small plant, and the pressure system component
manufacturer. They had noted the attenuation data provided for the protector but no
estimate of the attenuation provided or required in their work situations had been made.
Workers employed by the small plant manufacturer were seen wearing earplugs in work
areas where for sustained periods A-weighted noise levels were below 75dB. These
low noise areas had been included in an extensive hearing protection zone making
hearing protector use mandatory.
Six had not considered the attenuation. The confectionary manufacturer required
earplugs with tracers and these types of protector were only available as high
attenuation earplugs so attenuation was not an available choice. The bottling plant had
noted the attenuation but confessed to using what they had always used. The remaining
four were all the small employers; the car servicing centre, the specialist joinery
workshop, the printers, and the sheet metal workshop. They had insufficient
understanding of attenuation to use the data provided with the protectors.
Figures 1 and 2 show graphically the sound pressure levels where the hearing protectors were
seen in use, plotted against the hearing protector SNR value. (The single number rating (SNR)
value is provided for all CE marked hearing protectors. The SNR provides a simple estimate of
the protection after correction for the frequency content of the noise.) Figure 1 shows the
results for earplugs; Figure 2 the results for earmuffs. The bars show the sound level range at
each employer or outdoor situation where the hearing protector was used and the centre marker
on the bar indicates the median sound pressure level. A marker on its own indicates a single
value where the sound level for only one operation was recorded.
Over the results in Figures 1 and 2 are red lines marking boundaries of the SNR value likely to
be suitable for different levels of noise. The range marked by the red lines is an approximate
guide given in HSE’s guidance to the Control of Noise at Work Regulations, not a standard
method for selecting appropriate protection. Data points within these lines correspond to
hearing protection estimated to provide an appropriate level of protection. Data points below
the lines correspond to possible over protection (too much protection). Data points above
correspond to possible under protection (insufficient protection).
- 12 -
In summary:
Most employers were issuing hearing protection without considering whether the level
of protection was appropriate. Figures 1 and 2 show that in about half of the cases seen
wearers are potentially overprotected, especially where earplugs are used. This problem
reflects poor selection.
Hearing protection was sometimes being over used because hearing protection zones
were too extensive.
105
100
Sound pressure level dBA
95
90
85
80
75
70
20
22
24
26
28
30
32
34
36
38
40
Manufacturer's quoted SNR value dB
Figure 1 Sound level where earplugs were worn against quoted SNR value
110
105
Sound pressure level dBA
100
95
90
85
80
75
70
20
22
24
26
28
30
32
34
36
38
40
Manufacturer's quoted SNR value dB
Figure 2 Sound level where earmuffs were worn against quoted SNR value
- 13 -
3.1.5
Selection according to audibility requirements
Only the county council safety team mentioned the problem of audibility as a factor in their
choice of hearing protection. They reported the highway maintenance team’s view of hearing
protection was, “I’d rather be deaf than dead”. Low attenuation earmuffs and banded plugs
had been provided; but safety staff were unaware of the possible benefits of flat frequency
response protectors or sound restoration protectors. As a result of the visit they trialled these
types of protector in 2008.
The metal fabricated buildings manufacturer mentioned the problem of a hearing aid user.
Passive earmuffs over the aid tended to increase the condensation causing the ear tubes of the
aid to block, leaving the user with very little hearing. Again the employer was unaware of the
possible benefits of sound restoration earmuffs with features designed to enhance hearing for
those with a hearing loss.
In summary:
Audibility was not a factor generally considered when selecting hearing protection.
Where audibility was known to be important there was little awareness of the
availability or benefits of specialist hearing protection.
3.2
USE OF HEARING PROTECTION
3.2.1
Use as part of a noise control programme
HSE says hearing protection should be used as part of a noise control programme, rather than a
stand-alone measure. It is the first consideration when a risk is identified, but in the longer term
noise controls should be implemented and hearing protection should only be used where a risk
remains.
Hearing protection should only be provided with training on its use and the noise risk, together
with consultation on its use.
Only 6 out of the 15 employers visited had introduced hearing protection as part of a more
comprehensive noise control programme. These six included large, medium and small
employers. These six had introduced noise controls or had a policy of purchasing quiet tools
and machinery. Two other employers wanted to ban radios to reduce noise levels. The
remaining seven premises that had no existing or planned noise controls included large,
medium, and small employers.
3.2.2
Training, consultation and maintenance of use
Out of the 15 employers seen:
Two small employers and one medium size employer had provided no training and one
small employer provided training known to be ineffective. These were the specialist joinery
workshop, the sheet metal workshop, the printers, and the vehicle service centre.
The manager/ owner of the joinery workshop commented:
“Training, what training, I just give them the muffs”
The vehicle service centre safety officer said:
- 14 -
“I give them a two hour safety talk when they start and everybody gets a folder with the
company safety policy. If they don’t understand it, if they don’t read it it’s their fault. I’ve met
the law”.
At both the joinery workshop and vehicle service centre there were no signs advising where
hearing protection was required. Hearing protector use was uncontrolled at the joinery
workshop and at the vehicle service centre the only person seen using hearing protection seemed
unfamiliar with it and only used it when shouted at by the safety officer.
The sheet metal workshop and the printers also provided no training. There were no signs about
hearing protection at the sheet metal workshop but the employees had previous experience of
using hearing protection and were well motivated. Hearing protection here was worn
consistently and well with hand held power tools. Noisy machines were clearly labelled at the
printers. The staff were well motivated and had been consulted on the choice of hearing
protection. The two operators required to wear hearing protection used it consistently but they
did not know how to fit the compressible foam earplugs provided.
Five provided training on induction but no follow up training. These were medium to large
employers. Hearing protector use was seen in use during normal working at only three of these
five sites; the vehicle component manufacturer, the ironwork restorer, and the pressure system
component manufacturer. Of the remaining two, the bottling plant was shut down, and the
confectionary manufacturer did not allow access.
At the pressure system component manufacturer hearing protectors, earmuffs and earplugs,
were consistently used and well fitted. Induction training on hearing protection covered care of
the protectors and advice on fitting. The advice on fitting was taken from the instructions
provided with the protectors. Staff were consulted on the choice of hearing protection.
At the vehicle component manufacturer three out of ten staff seen in a hearing protection zone
were not wearing hearing protection. Those using custom moulded earplugs and earmuffs had
them well fitted, but three out of four staff using compressible foam plugs had them poorly
fitted. The company had 70 staff on a Dupont Stop Observation programme.
Only one person at the ironwork restorer was engaged in noisy work during the visit and he was
using over-the-head earmuffs with the band around the back of the head, although there was no
apparent reason preventing proper fitting. Another employee was able to demonstrate that they
could fit the compressible foam earplugs moderately well. The company kept a register of
hearing protection issued and ensured replacement on a regular basis.
Six had recently provided training or provided training on a regular basis. These included
small to large employers; the metal fabricated buildings manufacturer, the vehicle accident
repair centre, the joinery factory, the manufacturer of small plant machinery, the county council,
and the cement works. No site visit was made with the county council to see hearing protector
use.
The metal fabricated buildings manufacturer had recently recruited a new safety officer. She
had trained all staff in groups of six within the previous month. Hearing protection was being
used consistently and well; apart from one person seen with compressible foam plugs poorly
fitted.
The staff at the large joinery factory had received recent training from the manufacturer
supplying the hearing protection. However staff had objected to the imposition of hearing
protection and attempts to ban radios and most staff were seen wearing the push in foam
- 15 -
earplugs with a rigid centre, across the pinna rather than in the ear canal. The less popular
flanged earplugs and overhead earmuffs were being worn correctly.
The manufacturer of small plant machinery provided training on induction and two monthly
safety training sessions using an external consultant. Hearing protector use was mixed, earplugs
were well fitted by 11 out of 13 users one noisy area, however all 10 staff seen working in
another area within the hearing protector zone, where A-weighted noise levels exceeded 85dB,
were not using hearing protection. Workers were also seen using hearing protection in areas
designated hearing protection zones where A-weighted noise levels at the time of the visit were
between 73 and 75dB.
The accident repair centre used a training provider for regular safety training and held 6monthly health and safety meetings with the staff. All PPE issued was checked each month and
tools requiring the use of hearing protection were all identified. Despite this the manager said
motivating people to use the hearing protection was a problem. No noisy activities were seen
during the visit but the staff demonstrated that they could fit earmuffs and compressible foam
earplugs moderately well. All staff were seen to have earmuffs marked with their name.
The cement works provided toolbox talks on different health and safety issues every six months
and more detailed training to managers and supervisors. Supervisors and workers were
instructed to ensure everyone was using hearing protection correctly. Two incidences of wellfitted heavy-duty helmet mounted earmuffs were seen at the cement works, no other workers
were seen in the noisy areas.
The county council provide training demonstrations on how to fit hearing protection and had
trained all road workers in the previous 12 months. A new one-week induction training was
being planned together with refresher courses on health and safety. The council safety officers
considered that supervision of hearing protector use was the weakest link as supervisors on site
preferred to be seen as part of the team rather than a heavy handed manager.
Of the outdoor teams seen it was confirmed that the community punishment team received a
two-hour initial training session on the use of the machinery and necessary PPE.
In summary:
Training on its own did not guarantee the good use of hearing protection.
Good hearing protector use also requires the cooperation of the staff.
Good hearing protection use was seen where no formal training had been provided.
Poor hearing protector use was seen where recent training had been provided but where
there were poor relations between staff and management over the issue of noise control.
Three small employers were unaware that training was required.
3.2.3
Use of earmuffs
12 out of 15 employers included earmuffs in the choice of protectors available. Earmuffs were
seen in use at eight of the fifteen employers visited. All four groups of outdoor workers
encountered only had earmuffs available.
The earmuffs at the small specialist joinery workshop and those seen worn by a road worker
were in poor condition with dilapidated seals and poor tension. In addition the joinery
- 16 -
workshop earmuffs had damaged cups and glued head band joints preventing any flexibility (see
Figure A1 in Appendix subsection 9.5).
The manager of the joinery workshop said, “They can’t have new equipment until they can take
better care of it”.
The community punishment workers were reluctant to use the earmuffs provided because they
were shared and although they appeared in good condition they were unsure if they were ever
cleaned.
When other head-worn PPE or clothing was used earplugs were generally used instead of
earmuffs. However two outdoor workers were seen on a cold day wearing earmuffs over hats,
hoods, eye protection and facemasks (see Figure 10 in Appendix A). The earmuffs provided for
the community punishment teams fitted poorly over the face visors also being worn. Earmuffs
had been chosen for the community punishment teams on the basis of cost, rather than
compatibility with other PPE.
One person was seen with over-the-head band of his earmuffs worn behind the head during the
planned visits to premises, and one outdoor worker was seen with his muffs similarly worn
incorrectly. This is likely to provide a poor fit and reduced attenuation.
Apart from these exceptions, earmuffs seen were generally in good condition and worn
correctly.
Where helmets were also worn helmet mounted earmuffs were the only option seen in use.
In summary:
Earmuffs seen in use were generally but not universally in good condition and properly
worn.
Where hearing protection was required with other headworn PPE, integral earmuffs or
earplugs were the preferred choice.
Two workers were seen wearing earmuffs over outdoor clothing, and in another case
earmuffs were provided for use with a visor that prevented a proper fit.
The problem of outdoor workers wearing earmuffs over clothing is a difficult one to
resolve without an available solution. Clothing that can accommodate the wearing of
earmuffs underneath is not obviously available.
Some employers allow, either by act or omission, dilapidated and ineffective hearing
protection to be kept in use.
Some employers were requiring use of shared earmuffs without the means to ensure
they were cleaned between use. HSE guidance recommends use by one person only, or
where earmuffs are kept for visitors cleaning for each new wearer.
3.2.4
Use of earplugs
Earplugs were seen in four main types:
Custom-moulded where an ear-plug is produced in a durable plastic to the shape of the
ear canal and pinna of the user.
- 17 -
Compressible foam where the earplug is entirely made of a foam that is compressed to
allow insertion into the ear canal, and then expands to fill the canal.
Push-in-foam where the earplug is made of foam around a rigid centre core, or as foam
attached to a rigid handle. This type is pushed into the ear canal without
precompression.
Flanged is a preformed plastic plug with increasing diameter flanges around a centre
core. It is pushed into the ear canal.
14 out of the 15 employers provided earplugs.
3.2.4.1
Custom moulded
The vehicle component manufacturer and the metal fabricated buildings manufacturer provided
custom-moulded earplugs containing filters to control the attenuation provided. The vehicle
component manufacturer had been using custom moulded earplugs for 15 years and provided
these to staff working in areas where hearing protection use was compulsory after completion of
6 months employment. The metal fabricated buildings manufacturer provided them to all staff.
The cement works was also trialling custom-moulded earplugs.
Where custom-moulded earplugs were used they appeared to be well fitted, but not universally
preferred. Some workers still preferred foam or flange type disposable earplugs for comfort.
The vehicle component manufacturer reported that some users did not find them comfortable
and that they were sometimes found to be defective at the annual service.
3.2.4.2
Compressible foam
Compressible foam plugs were available at 12 premises visited. A visual inspection showed
that out of 14 people seen with them fitted, only 6 had inserted the plug well into the ear canal.
When asked to demonstrate fitting the most common incorrect method seen was to roll one end
into a point and to then attempt to push the plug into the ear canal. They were unaware of the
need to compress the plug along the whole length. From a visual inspection compressible foam
earplugs appeared to be the least well fitted of the earplug types available.
3.2.4.3
Push-in-foam
These were available at 4 of the 15 premises visited. The most common type seen was the type
with the rigid core. In the joinery factory these earplugs were deliberately worn across the
pinna by all but one employee. If this premises is discounted then out of 16 people seen
wearing this type of earplug 12 appeared to have them fitted well into the ear canal.
3.2.4.4
Flanged
These were available at 6 out of the 15 premises visited. All those seen wearing this type
appeared to have them well fitted into the ear canal.
In summary:
Some users found custom moulded earplugs uncomfortable. This suggests that these
earplugs may sometimes be providing a poor fit.
Compressible foam types were the most commonly provided earplug type and from a
visual inspection these were more likely than others to be poorly fitted. The push in
- 18 -
plugs, both foam and flange types appeared to be better fitted, with a greater depth in
the ear canal, suggesting that they were easier to fit.
3.2.5
Reasons for not wearing hearing protection
During planned visits to premises most workers were seen using hearing protection during noisy
work and in hearing protection zones, but there were instances of workers not using hearing
protection.
The reasons given for not using hearing protection were:
Cleaners aren’t given hearing protection as hearing protection zones don’t apply to
them.
I want custom moulded earplugs; foam earplugs make it too hard to hear.
I don’t know who last used them (earmuffs). We have to share and they aren’t cleaned.
Earplugs stop you hearing the radio.
Nothing has been done to make things quieter. They just give us earplugs and take
away our radios.
I’d rather be deaf than dead.
Audibility of warning sounds and radios is a reason.
Users were reluctant to use hearing protection when they perceive that the reduced
audibility is an immediate risk. Roadworkers in particular mentioned audibility of
moving traffic as a factor.
In repetitive work hearing the radio was important to workers.
No employer visited had considered alternative hearing protection with radio or
facilities for enhancing communication, such as sound restoration or flat frequency
response protectors. This appeared to be due to lack of awareness rather than the
additional cost involved.
Peer pressure is a reason.
In the large joinery factory push in foam earplugs were the most common choice and
these were deliberately worn across the pinna with only one worker seen with them
fitted correctly in the ear canal.
In the small plant machinery factory most workers were seen wearing hearing
protection except for all ten workers on the same noisy production line.
Management and worker attitude is a reason.
At the specialist joinery workshop, noise was considered by the owner to be part of the
job and hearing protection was not in a fit state to be used.
At the vehicle-servicing centre the safety officer considered safety was about being seen
to meet the regulations. On the day of the visit the earmuffs in the workshop areas were
all new, but use was poor. As staff were unaware of when to use them, whose earmuffs
- 19 -
were whose, and even where to find them immediately it seems likely the earmuffs had
only been provided because of the visit.
The community punishment management were aware that their teams were reluctant to
use hearing protection because it was shared, but said they were unable to pay for
individual issue of PPE.
3.2.6
Hearing protection use where there is no risk
Three employers issued hearing protection without having made a noise assessment or a risk
assessment (vehicle service centre, specialist joinery workshop, sheet metal workshop). The
ironwork restorer management was unsure whether an assessment had been made. All other
employers visited had identified the tasks and areas where hearing protection was required from
a risk assessment.
Without a risk assessment there is a danger of inappropriate hearing protection use. The vehicle
service centre safety officer wanted the valeting team to use hearing protection when using
vacuum cleaners. The noise from the vacuum cleaners was measured on the day of the visit and
found to be below 80dB when used inside a vehicle.
Hearing protection was also being used excessively at the manufacturer of small plant
machinery. The noise risk assessment had been used to designate whole buildings as hearing
protection zones because they contained localised areas where personal noise exposure could be
between 80 to 85dB. These hearing protection zones also contained work areas where levels
were below 80dB. In these areas hearing protection was seen in use where levels were between
73 and 75dB.
In summary:
Hearing protection was used where there was no risk to hearing. This occurred when an
employer had made a large area a hearing protection zone, in response to a risk in only
parts of the area.
One employer also considered issuing hearing protection as a blanket measure rather
than assessing the actual risk.
- 20 -
4
LABORATORY TESTS OF EARMUFF INSERTION LOSS
4.1
MIRE INSERTION LOSS TEST METHOD
Measurements were made of the insertion loss of earmuffs (difference in level at the ear with
and without the earmuff worn) when new, aged or damaged, and when worn with other head
worn PPE. All measurements were made using a MIRE (microphone in real ear) method.
Four test subjects from the staff of the noise and vibration and the personal protective
equipment teams were used. All were familiar with using PPE.
Each subject was seated in a diffuse sound field of pink noise. A miniature microphone at the
entrance of each ear canal recorded the sound level and spectrum with and without the earmuffs
worn. The difference in level with and without the protector provided the insertion loss of the
earmuff in each frequency band. A listing of the test equipment is given in Section 7 of this
report.
In the standard test (BS EN 24869-1) used to provide the protection data for CE marked hearing
protection subjects are asked to adjust the protector against a background noise until they
perceive they have achieved optimum protection. In these tests subjects were asked to fit the
protector as they would normally but then not to adjust the position. When fitting with other
head worn PPE subjects were asked to fit the protector in the best way they felt was secure and
comfortable. No assistance was provided with fitting.
4.2
EARMUFFS SELECTED FOR TESTING
Eight models of earmuffs were selected for inclusion in the tests, representing the range of
earmuffs on the market. A range from lightweight low attenuation earmuffs to heavy-duty high
attenuation earmuffs was chosen. The earmuffs are listed in Table 2 with the SNR value
provided by the manufacturer of the earmuff and the cost.
Table 2 Models of earmuff tested
Earmuff number and model
1 Basics Supamuff
2 Basics E Muff
3 Bilsom Viking V1
4 Bilsom Clarity C2
5 Peltor Optime II (headband)
6 Peltor Optime II (neckband)*
7 Peltor Optime II (helmetmounted)
8 Peltor Optime III
Description
Lightweight, multi position plastic band
Lightweight, multi position plastic band
Lightweight, multi position plastic band
optional head strap
Midweight, multi position plastic band
optional head strap
Midweight, wire type band fixed in over
orientation
Midweight, wire type band fixed in behind
orientation
Midweight, helmet-mounted
with
SNR dB
23
28
30
Cost
£4
£5
£7
with
30
£10
head
31
£12
neck
31
£12
30
£13
35
£14
Heavyweight, wire type band fixed in over head
orientation
*
Earmuff 6 (Peltor Optime II) has a band designed to be worn around the neck only. This earmuff used a fabric head
strap to provide additional support. Three examples of this earmuff bought for testing had faulty straps that
sometimes prevented the subjects from securing the earmuffs correctly.
- 21 -
4.3
TESTING EARMUFFS WORN WITH OTHER PPE AND CLOTHING
Earmuffs in their new condition were tested with and without other head worn PPE and
clothing. Where no PPE was used the earmuffs were worn with the headband in the overhead
orientation except for earmuff 6, which could only be worn with the band around the neck.
When worn with other PPE the best orientation of the earmuff headband was left to the test
subject’s discretion.
Earmuffs 3 and 4 were tested with and without their fabric head strap when worn with the
helmet.
The attenuation results with and without PPE and clothing are given in Table 3. Figure 3 shows
the PPE worn in these tests.
Hood
Beany Hat
Helmet and
zero hood
Helmet
Safety glasses
Small goggles
Large goggles
Visor
Bump Hat
Dust mask
Figure 3 PPE and clothing worn with earmuffs during laboratory tests
4.4
TESTING EARMUFFS IN DIFFERENT CONDITIONS AND
ORIENTATIONS
In addition to testing new earmuffs with and without other head-worn PPE, the effects of
damage and wear were also investigated. These conditions were:
simulated use and ageing,
punctured cup seal (where a liquid seal was provided),
broken seal,
- 22 -
headband stretching.
Each condition was tested with the band worn over the head and behind the head, with the
exception of the Peltor Optime II neckband and helmet mounted versions that were only worn in
the proper orientation.
4.4.1
Simulated use and ageing
Samples of all earmuff models were placed in a temperature of 40°C, over a spacer simulating
the tension during normal wearing, for seven days. This simulated approximately four weeks
wearing of the earmuff for 40 hours a week. Figure 4 shows untreated new earmuffs on the left
and the treated earmuffs on the right (the helmet mounted earmuff 7 is not included in the
photograph). There is a visible slackening of headband tension on earmuffs 1 to 4 that have the
plastic headband when compared to the new earmuffs. There is no visible change to earmuffs 5,
6 and 8 with the wire headbands.
- 23 -
Layout of earmuffs
2 1 3 6
5 4 8
Figure 4 New (left) and artificially aged earmuffs (right)
4.4.2
Stretching of headbands
The wire banded earmuffs (numbers 5, 6 and 8) can be stretched by pulling out the curved band.
New models of these earmuffs were stretched by holding them flat for one minute. They were
then left to recover for at least a day before measurements of the insertion loss were made.
4.4.3
Puncture to cup seal
The Peltor Optime II models have a seal containing foam over a sealed liquid layer. All other
earmuffs tested had a foam seal only. The Optime II models (earmuffs 5, 6, and 7) were tested
after a small puncture was made in the liquid seal.
4.4.4
Break in cup seal
Slitting the outside and removing about an eighth of the circumference of the inside foam as
shown in Figure 5 provided simulation of a severe break in the cup seal. The additional liquid
seal in the Peltor Optime II earmuffs was also cut.
Figure 5 Break to cup seal simulating seal damage
- 24 -
4.5
EARMUFF PERFORMANCE RESULTS
Earmuff insertion loss was recorded for third octave bands from 50Hz to 10kHz. To allow a
simple comparison the SNR value for each ear was calculated from these results. Figures 6 and
7 report the mean and range of the SNR results for each ear of each subject. Figure 6 gives the
results for new earmuffs worn with and without other PPE. Figure 7 gives the results for new,
artificially aged and damaged earmuffs in overhead and around the neck orientations. Table 3
(following Figure 6) and Table 4 (following Figure 7) report the same results in a numerical
format with results for damaged or aged earmuffs, and new earmuffs worn with other PPE given
as values relative to the mean result for a new earmuff worn without other PPE.
- 25 -
Figure 6 Measured SNR values (mean and range) for new earmuffs worn with and without other PPE
Basics E muff (earmuff 2)
35
35
30
30
Measured SNR value dB
Measured SNR value dB
Basics Supamuff (earmuff 1)
25
20
15
10
5
25
20
15
10
5
0
0
No PPE
Hood
Beanie
hat
Helmet
Bump
hat
Safety
Small
Large
glasses goggles goggles
Visor
Dust
mask
No PPE
Hood
Helmet
Bump
hat
Safety
Small
Large
glasses goggles goggles
Visor
Dust
mask
Bilsom Clarity C2 (earmuff 4)
35
35
30
30
Measured SNR value dB
Measured SNR value dB
Bilsom Viking V1 (earmuff 3)
Beanie
hat
25
20
15
10
5
25
20
15
10
5
0
0
No PPE Hood
Beanie Helmet Helmet
hat
+ strap
Bump Safety Small Large
hat glasses goggles goggles
Visor
Dust
mask
No PPE Hood
- 26 -
Beanie Helmet Helmet
hat
+ strap
Bump Safety Small Large
hat glasses goggles goggles
Visor
Dust
mask
Figure 6 (continued) Measured SNR values (mean and range) for new earmuffs with other PPE
Peltor Optime II neckband (earmuff 6)
35
35
30
30
Measured SNR value dB
Measured SNR value dB
Peltor Optime II headband (earmuff 5)
25
20
15
10
5
25
20
15
10
5
0
0
No PPE
Hood
Beanie
hat
Helmet
Bump
hat
Safety
Small
Large
glasses goggles goggles
Visor
Dust
mask
No PPE
Hood
Helmet
Bump
hat
Safety
Small
Large
glasses goggles goggles
Visor
Dust
mask
Visor
Dust
mask
Peltor Optime III headband (earmuff 8)
Peltor Optime II helmet mounted (earmuff 7)
35
35
30
30
Measured SNR value dB
Measured SNR value dB
Beanie
hat
25
20
15
10
5
25
20
15
10
5
0
0
Helmet
only
Hood
Beanie hat Zero hood
Safety
glasses
Small
goggles
Large
goggles
Dust mask
No PPE
- 27 -
Hood
Beanie
hat
Helmet
Bump
hat
Safety
Small
Large
glasses goggles goggles
Table 3 Change of earmuff SNR value as mean (shown in bold) and spread from mean when
worn with other PPE
Note 1: For earmuffs 1 to 6 and earmuff 8 the reference condition is the result without additional PPE. For
earmuff 7 (helmet mounted) all measurements, including the reference condition, is with the earmuffs worn
on the helmet.
Note 2: Earmuffs 3 and 4 are reported with and without the earmuff headstrap when worn around the neck
with the helmet.
Note 3: Column 2 gives the manufacturer’s SNR value obtained in accordance with BS EN 24869-1.
Earmuff
no.
Man.
SNR
Reference
Hood
Beanie
hat
1
23
19.5
+1.5, -1.5
2
28
21.5
+3.5, -3.5
3
30
25
+2.0, -4.0
-5.5
+1.0,
-1.0
-8.0
-0.5,
+0.5
-11.5
+1.5,
-0.5
-4.5
+1.0,
-2.0
-7.0
+1.5,
-2.5
-8.5
+1.5,
-2.5
30
23.5
+6.5, -9.5
-9.5
+2.0,
-1.0
-6.5
+2.0,
-3.0
5
31
25.5
+4.5, -5.5
6
31
23.5
+6.5, -8.5
7
30
23.5
+5.5,-8.5
-10.5
+1.0,
-1.0
-8.0
+1.5,
-2.5
-9.0
+2.5,
-5.5
-7.5
+3.0,
-2.0
-4.5
+2.0,
-2.0
-6.0
+2.5,
-1.5
8
35
30.5
+3.5, -1.5
-14.5
+2.0,
-2.0
-9.5
+2.0
-2.0
Helmet
and
“zero”
hood
strap
4
strap
-10.0
+1.5,
-1.5
Helmet
Bump
hat
Safety
glasses
Small
goggles
Large
goggles
Visor
Dust
mask
-2.5
+3.0,
-3.0
-7.0
+5.5,
-6.5
-8.0
+8.0,
-9.0
-5.0
+8.0,
-11.0
-9.0
+3.5,
-1.5
+4.5
+2.5,
-4.5
-7.5
+8.0,
-5.0
-5.0
+9.5,
-13.5
reference
condition
+5.5,
-8.5
-5.5
+3.0,
-3.0
-6.0
+3.5,
-3.5
-9.0
+8.5,
-6.5
-9.5
+10.5,
-6.5
-3.5
+3.0,
-2.0
-8.5
+4.0,
-2.0
-5.5
+3.5,
-2.5
-1.0
+1.5,
-3.5
-2.0
+2.5,
-4.5
-2.0
+3.0,
-6.0
-3.0
+1.5,
-5.5
-9.0
+6.5,
-4.5
-8.0
+6.0,
-5.0
-1.0
+1.5,
-1.5
-4.5
+5.0,
-6.0
-2.5
+3.5,
-4.5
0.0
+1.5,
-1.5
-2.5
+3.0,
-4.0
-2.0
+4.0,
-7.0
-13.0
+6.5,
-4.5
-6.0
+4.5,
-6.5
-2.0
+3.5,
-5.5
-7.0
+5.5,
-3.5
-7.0
+7.5,
-9.5
-1.0
+4.5,
-5.5
-11.0
+9.5,
-6.5
-10.0
+6.5,
-6.5
-6.5
+6.0,
-5.0
-8.0
+11.5,
-10.5
-5.5
+6.0,
-5.0
-0.5
+3.0,
-8.0
-1.0
+6.5,
-8.5
-2.0
+3.5,
-7.5
-6.0
+6.5,
-7.5
-6.0
+7.5,
-10.5
-10.0
+3.5,
-5.5
-2.5
+5.0,
-5.0
-1.5
+6.0,
-17.0
0.0
+2.5,
-2.5
-5.0
+9.5,
-13.5
-3.0
+5.5,
-7.5
-7.0
+2.5,
-5.5
-5.5
+3.0,
-4.0
-3.0
+4.5,
-9.5
-7.5
+4.0,
-14.0
-3.0
+1.5,
-3.5
-2.5
+1.0,
-3.0
In summary
The reference SNR values, obtained without additional clothing or PPE, were on average 5.5dB less
than the manufacturer’s SNR values. The manufacturer’s value is based on the mean minus one
standard deviation that corresponds to the minimum protection for 84% of wearers in the BS EN
24869-1 standard test.
The SNR value generally decreases when earmuffs are worn over other PPE or clothing. However
the SNR of earmuff 4 did not decrease when worn in the behind the neck orientation with the helmet
when the supporting head strap was also used, and the decrease in the average SNR values for the
test earmuffs when worn with the small goggles was less than 3dB. This confirms that some
- 29 -
compatible hearing protection and PPE combinations are available that minimise the possible loss of
earmuff attenuation.
The attenuation of an earmuff worn over clothing appears to be relatively independent of the stated
attenuation for that protector. All results for earmuffs worn over the hood or beanie hat lie close
together. This may be due to limiting of the maximum attenuation by the layer of fabric between the
earmuff seal and the head.
There is a wide variation between the attenuation achieved by different subjects when earmuffs are
worn with PPE with a protruding part that passes under the cup breaking the seal, or with PPE that
prevents the correct fitting of the headband. The results for earmuff 6 (neckband Peltor Optime II)
show some very low SNR values were obtained when worn with other PPE. This is due to increased
difficulties fitting the defective earmuff head straps with other PPE.
The small goggles gave a mean reduction in SNR of less than 2dB. However the glasses and
goggles were more obtrusive and reduced earmuff SNR by as much as 10dB.
- 30 -
Figure 7 SNR values for new, aged and damaged earmuffs
Worn in both overhead and behind neck orientation
Basics E Muff (earmuff 2)
35
35
30
30
Measured SNR value dB
Measured SNR value dB
Basics Supamuff (earmuff 1)
25
20
15
10
5
25
20
15
10
5
0
0
New head
New neck
Aged head
Aged neck
Broken seal
head
Broken seal
neck
New head
Aged head
Aged neck
Broken seal
head
Broken seal
neck
Bilsom Clarity C2 (earmuff 4)
Bilsom Viking V1 (earmuff 3)
35
35
30
30
Measured SNR value dB
Measured SNR value dB
New neck
25
20
15
10
5
25
20
15
10
5
0
0
New head
New neck no
strap
New neck
with strap
Aged head
Aged neck
Broken seal Broken seal
head
neck
New head
- 31 -
New neck no
strap
New neck
with strap
Aged head
Aged neck
Broken seal Broken seal
head
neck
Figure 7 (continued) SNR values for new, aged and damaged earmuffs
Worn in both overhead and behind neck orientation except for neckband and helmet mounted earmuffs
Peltor Optime II neckband (earmuff 6)
35
35
30
30
Measured SNR value dB
Measured SNR value dB
Peltor Optime II headband (earmuff 5)
25
20
15
10
5
25
20
15
10
5
0
0
New head New neck
Aged
head
Aged
neck
Broken
Broken Stretched Punctured Punctured
seal head seal neck
head
seal head seal neck
New neck
Broken seal neck
Stretched neck
Punctured seal
neck
Peltor Optime III headband (earmuff 8)
35
35
30
30
Measured SNR value dB
Measured SNR value dB
Peltor Optime II helmet mounted (earmuff 7)
Aged neck
25
20
15
10
25
20
15
10
5
5
0
New head
0
New
Aged
Broken seal
Punctured seal
- 32 -
New neck
Aged head
Aged neck
Broken seal Broken seal
head
neck
Stretched
head
Table 4 Change of earmuff SNR value when worn in different orientations and
when aged or damaged
Note 1: The mean value for each earmuff reference condition is reported as the actual SNR
value. All other mean values for the earmuff are reported as the difference from the reference
condition. All mean values are shown in bold.
Note 2: The spread around each mean value is shown in ordinary type and is the subject
variation around the specific condition mean value above.
Note 3: For earmuffs 1 to 5 and earmuff 8 the reference condition is the result for a new earmuff
worn in the over head orientation. Earmuffs 6 and 7, that are neckband and helmet mounted
types, could only be worn in their intended orientation and the reference condition is therefore
for a new earmuff worn in that intended orientation.
Note 4: Earmuffs 3 and 4 are reported with and without the earmuff headstrap when worn
around the neck in the new condition.
Note 5: Column 2 gives the manufacturer’s SNR value obtained in accordance with BS EN
24869-1.
New
Earmuff
No
Man.
SNR
1
23
2
28
21.5
+3.5, -3.5
3
30
25
+2, -4
30
23.5
+6.5, -9.5
5
31
25.5
+4.5, -5.5
6
31
7
30
Reference
condition
behind
neck
23.5
+5.5, -8.5
Head
(ref)
19.5
+1.5, -1.5
+
strap
4
+
strap
Aged
neck
head
neck
head
neck
0.0
+1.5,
-1.5
-1.0
+3.5,
-3.5
-4.5
+6.5,
-9.5
-2.5
+7.5,
-7.5
-2.5
+6, -9
+3.5
+3, -3
-3.5
+2,
-4
-8.5
+6,
-5
-7.5
+4.5,
-6.5
-8.0
+5.5,
-4.5
-10.5
+7,
-8
-15.5
+5.5,
-3.5
-3.5
+4,
-1
-4.0
+1.5,
-2.5
-1.0
+4,
-4
-4.5
+4,
-3
-7.5
+4,
-7
-3.5
+4.5,
-3.5
-1.5
+4,
-9
-9.0
+4.5,
-5.5
+2.0
+4.5,
-7.5
-4.5
+5,
-12
-4.5
+5,
-3
23.5
+6.5,
-8.5
+2.0
+3.5,
-6.5
-5.5
+7,
-7
+3.0
+3.5,
-7.5
+1.5
+3,
-4
-5
+6.5,
-8.5
-3.5
+6,
-9
0.0
+2.5, -8.5
helmet mounted
8
35
30.5
+3.5, -1.5
Broken seal
-2.5
+2, -3
head
neck
-3.0
+4.5,
-4.5
+1.0
+3.5,
-3.5
-5.0
+4.5,
-6.5
+2.0
+2.5,
-3.5
-3.0
+6.5,
-7.5
+0.5
+4, -12
helmet mounted
helmet mounted
-4.0
+7.5,
-3.5
- 33 -
Punctured seal
-5.5
+9, -6
-0.5
+3,
-4
-8.0
+4.5,
-3.5
Stretched
band
head neck
-3.0
+3.5,
-3.5
helmet mounted
-5.5
+5,
-8
In summary
Simulated use and ageing gave a visible loss of headband tension for the earmuffs with
a plastic headband (earmuffs 1 to 4). As a consequence the mean SNR value, for the
plastic headband aged earmuffs, dropped by between 1.5 and 8.5dB relative to the new
reference condition, when worn in the overhead orientation. A greater loss of
attenuation occurred for the behind the neck orientation.
For the wire band earmuffs (earmuffs 5 to 8) simulated use and ageing caused no visible
loss of headband tension and no significant reduction in attenuation. However
deliberate stretching of the wire headband on earmuffs 5, 6 and 8 caused a loss of
between 3 and 5.5dB relative to the new condition, when each earmuff was worn in the
intended orientation.
The loss of tension, whether by ageing or stretching, has caused a similar or more
severe reduction in attenuation than the more obvious damage to the earmuff seal. The
loss of attenuation caused by a broken seal relative to the results for the new,
undamaged condition was a negative loss of 2dB (actual increase in attenuation) down
to a loss of 4dB for the plastic headband earmuffs. For the wire headband earmuffs
the loss was from a negative loss of 1.5dB (increase in attenuation) down to a loss of
5.5dB.
Removal of an eighth section of the earmuff seal is a more obvious sign of damage, but
only caused a mean drop of 2dB in earmuff SNR.
Earmuffs 3 and 4 were supplied with a supporting headstrap, for use when worn in the
behind the neck orientation. Without the headstrap the attenuation reduced by 2 and
6dB. Models of earmuff 6 (Optime II neckband) were supplied with defective
headstraps that were too short to be used by every subject. This earmuff has a wider
spread of attenuation between subjects than the wire headband earmuffs (earmuffs 5 and
8) when worn in their intended over head orientation. The proper use of the headstrap
is therefore essential to obtain the optimum attenuation.
- 34 -
5
LABORATORY TESTS OF EARPLUG INSERTION LOSS
5.1
INSERTION LOSS TEST METHOD FOR EARPLUGS
Measurements were made to compare how the attenuation of earplugs varied with different
methods of fitting and insertion depth. Measurements were made of the sound level in a diffuse
field of random noise at the eardrum of a simulated ear on a KEMAR (Knowles Electronics
Manikin for Acoustic Research) head and torso simulator. The difference in level with and
without earplugs fitted was recorded as the attenuation. From the attenuation in octave bands
the SNR value for the earplug was calculated.
5.2
EARPLUGS SELECTED FOR TESTING
A range of earplugs were selected. The range was chosen from those known to be commonly in
use, and representative of the different types available: banded earplugs, banded earcaps,
compressible foam, push in foam, flanged and bulb shaped earplugs.
Table 5 shows the range of earplugs tested.
Table 5 Range of earplugs/ canal caps tested
Earplug model and number
1 EAR Caboflex
2 EAR Ultrafit 20
3 Howard Leight QB3
4 Howard Leight Quiet
5 EAR Classic
6 EAR Express Pod
7 EAR Ultrafit
8 Howard Leight Max
5.3
Description
Banded tapered canal cap
Corded premoulded flange earplug
Banded round ear canal cap
Premoulded bulb shape earplug
Compressible foam earplug
Foam earplug on stalk
Premoulded flange earplug
Compressible foam earplug
SNR dB
19
20
23
28
28
28
35
37
Cost
£4
£2
£3
30p
20p
50p
£1
20p
COMPARISON OF RESULTS FOR AN EAR SIMULATOR AND HUMAN
SUBJECTS
The attenuation of an earplug or canal cap in an ear simulator often exceeds the performance
achieved by human subjects as the earplug is fitted into a smooth cylindrical ear canal
simulator. The SNR value obtained by the standard EN 24869-1 method, supplied with the
earplug by the manufacturer, is therefore a better indication of the attenuation of a well fitted
earplug worn by a human subject. When an earplug is poorly fitted the difference between
simulator and the human subject performance will decrease as the achieved attenuation is less
dependent on the ear canal condition.
The results of the earplug insertion loss measurements obtained with KEMAR are shown in
Table 6. It should be remembered that the measurement method gives an indication of the
optimum attenuation for any fitting, and the predicted attenuation when worn by a human
subject will be lower.
- 35 -
Table 6 Earplug SNR taken from insertion loss measured with KEMAR ear
Earplug
Earplug
number
Man.
SNR
Fitting/ compression
Deep
insertion
Halfway
insertion
Edge of
canal
Compressible
foam
5
28
42
41
27
8
37
Whole length rolled
according to instructions
45
44
42
5
28
9
4
8
37
Folding along length or
squashing
4
Foam on stalk
6
28
Pushed into canal
44
32
28
Premoulded bulb
4
28
40
33
Variable
<34
Flanged (low
attenuation)
2
20
20
20
0
Flanged (high
attenuation)
7
35
44
20
0
Banded ear
canal caps
1
19
3
23
1
19
3
23
Ear cap inserted
according to instructions
37
Ear caps only held
against canal by
tensioned band
0
30
0
In summary:
To achieve the optimum attenuation, premoulded plugs must generally be inserted fully
to the intended insertion depth. However the low attenuation flanged earplug (number
2) gave the same attenuation when fully inserted and when only inserted to about half
its full depth.
Foam plugs should be rolled as specified by the manufacturer so they expand fully in
the ear canal. When folded or squashed they may not fill the ear canal when expanded
and so give virtually no protection even if deeply inserted.
Banded ear canal caps must be partially inserted into the ear canal as shown by the
fitting instructions. Caps held only against the canal entrance by the band may give no
protection.
- 36 -
6
QUANTIFYING THE EFFECTIVENESS OF HEARING
PROTECTION SEEN IN USE
Observation of hearing protector provision, use, and condition confirmed in some premises use
was ineffective and likely to provide no protection for the majority of workers requiring
protection. In other premises some workers were seen without hearing protection where hearing
protection was required.
Laboratory measurements tested the reduced attenuation of earmuffs worn with other PPE and
clothing, and the effect of ageing and damage. On site observation showed the problems of
wearing of earmuffs over other PPE was mostly avoided by choosing integral PPE or earplugs
rather than earmuffs, but the use of earmuffs over clothing by outdoor workers was a clear
problem.
Most earmuffs seen in use showed no obvious visual defects but the loss of headband tension
due to normal wear and ageing or by slight stretching is identified in laboratory tests as
significant factor.
Laboratory tests of earplugs were less conclusive because the normal variations due fit in a
human ear canal were difficult to reproduce using the simulated ear canal of the KEMAR
manikin. These tests did however highlight the negligible attenuation achieved by compressible
foam earplugs if incorrectly compressed before fitting.
The four factors given are above are considered below, in terms of frequency of occurrence or
estimated loss of attenuation, in order to quantify hearing protector effectiveness to the majority
of workers seen.
6.1
INEFFECTIVE USE OF HEARING PROTECTION
One outdoor team had only one pair of earmuffs for three workers using strimmers, and these
were not worn because workers considered these shared earmuffs unhygienic.
In three out of the twelve companies that allowed on site observation of hearing protector use
during normal working, use was ineffective. In the first (the vehicle servicing and repair centre)
this was due to the workers being unaware of when and where hearing protection should be
used, in the second (the joinery factory) the majority of workers were wearing their earplugs
outside the ear canal, and in the third (the joinery workshop) the earmuffs provided had broken
bands and severely damaged cups. The first two of these companies claimed to have provided
training on hearing protector use, the third company had been unaware any training was
required.
In five companies that had majority effective use of hearing protection there were areas where
hearing protection was required continuously. In two of the five hearing protection was unworn
by 3 out of 13 workers, and 10 out of 25 workers seen within noisy areas. In the other three no
one was seen not wearing hearing protection. The estimated ratio of those not using protectors
combined across all five companies, is one in seven.
There is insufficient information from this study to assess the incidence of occasional hearing
protector use.
- 37 -
Summary
One in four employers seen had ineffective use of hearing protection, such that the majority of
workers had nil protection.
An estimated one in seven workers, in companies with majority effective use of hearing
protection, failed to wear hearing protection when required.
6.2
UNDER PROTECTION
The laboratory measured SNR of earmuffs was on average 5.5dB below the quoted value. The
HSE method for selection of protectors derates the quoted attenuation by 4dB. The measured
SNR of plastic banded earmuffs reduced by a further average 5.5dB with the reduction in
headband tension caused by simulated ageing, and by an average of 4dB with a one minute
stretch of a wire banded earmuffs. Thus the typical attenuation of earmuffs in good condition
that have lost some tension due to normal use or stretching may on average be a further 6dB less
than predicted.
Figure 2 (shown previously) placed the sound level and quoted SNR value against the
approximate suitable SNR values given in HSE’s guidance to the Control of Noise at Work
Regulations. Figure 2 showed one user wore an earmuff predicted to under protect. Figure 8
below, shows graphically the sound pressure levels where hearing protectors were seen in use,
plotted against the SNR with a 6dB derating superimposed. The red lines indicate the boundary
of the approximate suitable SNR values given in the HSE’s guidance. Data points extending
over the top red line indicate probable under protection, data points below the lower red line
indicate probable over protection. There are 5 data points out of 16 where the hearing protector
SNR value is insufficient for the average sound pressure level and users are likely to be
underprotected. 2 data points out of 16 show over protection.
110
105
Sound pressure level dBA
100
95
90
85
80
75
70
16
18
20
22
24
Derated SNR value dB
- 38 -
26
28
30
Figure 8 Sound level against earmuff SNR value derated by 6dB for possible
ageing and headband stretching
Two outdoor road-workers wore earmuffs over clothing. The laboratory test results show new
earmuffs worn over clothing achieved an average SNR of no more than 21dB. The wearing of
earmuffs over clothing is common practice amongst outdoor workers in cold weather. A
protector with an SNR value of less than 20dB is only recommended by the HSE guidance for
use in sound levels below 90dB, clearly insufficient when large power tools are used.
Compressible foam earplugs were available in 12 of the 15 premises visited although where
there was a choice they were not the preferred choice of workers. 6 out of 14 workers seen
using compressible foam earplugs wore them only shallowly inserted, and most users asked to
demonstrate fitting did not compress them before fitting according to the manufacturers’
instructions. Laboratory tests show that an incorrect compression may prevent the earplug
expanding to fill the ear canal. Laboratory measurements show SNR values of less than 9dB for
incorrect compression. Compressible foam earplugs are specified with SNR values from 28 to
36. However it is possible that these earplugs are providing insufficient protection for a
significant proportion, and possibly a majority of users.
Summary
Laboratory tests show earmuff headband tension reduces with use, and stretching. Laboratory
tests suggested a reduction of 6dB from the manufacturer’s SNR value could be typical of
earmuffs with only moderate use. A 6dB reduction is estimated to result in a third of the
earmuffs seen in use under protecting.
Workers wearing earmuffs over clothing are likely to be under protected, as earmuff SNR
values are likely to be reduced to less than 21dB.
Most users of compressible foam earplugs fail to compress them according to the
manufacturer’s instructions. Laboratory tests show the earplug SNR can be reduced to 9dB and
below where incorrect compression is used.
- 39 -
7
7.1
CONCLUSIONS
WORKERS RECEIVING NO PROTECTION
A quarter of companies seen during normal working and one out of the four outdoor worker
teams were seen to have ineffective hearing protector use likely to result in negligible or zero
protection for the majority of workers.
In addition one in 7 workers in companies with majority effective hearing protector use were
seen without hearing protection when and where hearing protection was required.
Overall this suggests only 60% of workers expected to be using hearing protection are receiving
any protection.
One other factor likely to result in ineffective use is poor fitting. Most workers using foam
earplugs fitted them incorrectly. The laboratory tests show this may result in only negligible
attenuation (SNR values of less than 9dB) even if the earplug is deeply inserted.
7.1.1
Reasons for workers choosing not to use hearing protection
Workers cited needing to hear traffic and radios, and communication difficulties as reasons for
not using hearing protection.
Peer pressure is also a factor. Individuals were also less likely to use hearing protection when
those around them chose not to. Employers also reported, and it was apparent during
observations of hearing protector use, that supervisors were sometimes reluctant to enforce
wearing of hearing protection.
Worker attitude is another factor. Workers in one premises visited chose not to cooperate with
hearing protector use because they perceived it had been imposed without fair consultation.
Here earplugs were worn in the pinna and outside the ear canal, only a few were seen wearing
earplugs in the ear canal.
7.1.2
Factors in employers’ failure to ensure effective use
General lack of compliance and awareness was the common factor. The quarter of companies
that had ineffective hearing protector use had introduced hearing protection as the sole control
measure without a more comprehensive noise control programme. Two companies had also
made no assessment of exposure.
Inadequate provision was a factor in two cases. One employer had provided just two pairs of
broken earmuffs and had refused to replace them. One outdoor team had just one pair of
earmuffs for three workers operating noisy tools.
7.2
WORKERS USING HEARING PROTECTION WHEN NOT REQUIRED
At one site hearing protection was used where there was no risk to hearing. The employer had
made a whole building a hearing protection zone, in response to a risk in only part of the
building. Another employer was considering requiring hearing protection in all areas rather
than assessing the actual risk.
- 40 -
7.3
PROVISION OF HEARING PROTECTION
7.3.1
As part of noise control programme
40% of employers seen during the planned visits were supplying hearing protection as part of a
comprehensive noise control programme. These employers had introduced noise controls or
had a policy of purchasing quiet tools and machinery. Hearing protector use was effective for
the majority of workers in these companies.
7.3.2
Provision of choice
2 out of the 15 employers visited, and one outdoor team had no choice of hearing protection.
These three employers were unaware of the need to provide a choice.
7.3.3
Provision with training, supervision, and worker cooperation
80% of the employers visited said they provided some training in hearing protector use. The
type of training varied from hands on training in small groups to simply providing a copy of the
company safety policy. One manager said he was aware the training provided was ineffective,
but he considered he had met his responsibilities.
Training on its own did not guarantee the good use of hearing protection. Hearing protection
use was seen to be most effective in companies when combined with appropriate supervision
and employee cooperation.
It is questionable whether full effective use can be achieved all the time. Two employers who
had regular staff safety meetings, provided training and supervision, admitted they had
difficulties in ensuring consistent use of hearing protection. One cited peer pressures on
supervisors leading off-site teams.
7.4
CHOICE OF HEARING PROTECTION
7.4.1
As compatible with other PPE and clothing
All employers visited by appointment were providing hearing protection of a suitable type for
the work environment and for other personal protective equipment (PPE) being worn.
Outdoor workers were seen wearing earmuffs over clothing on a cold day; in laboratory tests
clothing limited attenuation, bringing SNR values down to 21dB or less.
Integral PPE and earmuffs were being provided, where required, with the exception of the
community punishment team who had banded earmuffs for use over visors. Laboratory tests
showed wearing over a visor gave on average a 3dB reduction in SNR, with increased
variability of SNR between users.
With the exception of the outdoor workers seen earplugs were provided where other head worn
PPE or clothing prevented proper use of earmuffs, and these were the preferred choice where
hearing protection was worn for long periods or the workplace was hot and dusty.
7.4.2
According to estimated attenuation
Less than half of employers visited had selected hearing protection according to the attenuation
required. As a consequence, in about half of the cases seen, the hearing protectors supplied
were predicted to over protect according to the manufacturers’ data.
- 41 -
Four employers visited had chosen hearing protection using standard methods or the HSE
calculators.
One employer required earplugs with tracers, and this restricted their choice to high attenuation
devices only.
7.4.3
With consideration of audibility and specialist hearing protection
One employer had considered audibility when selecting suitable hearing protection. There was
no awareness amongst any employers visited of the availability of specialist hearing protection
to help with audibility of important sounds within the workplace.
7.4.4
Hygiene considerations
Individual issue of earmuffs is normally recommended unless there is provision for cleaning.
Two employers required shared use of earmuffs, and in one group of outdoor workers gave this
as the reason for not using them.
It is essential earplugs are clean when inserted into the ear. Only one employer provided handwashing facilities adjacent to earplug dispensers.
7.5
REAL WORLD ATTENUATION OF HEARING PROTECTION
7.5.1
Earmuffs
HSE recommends derating the attenuation of hearing protection by 4dB when estimating
attenuation provided under real world conditions. Most earmuff users seen wore earmuffs with
intact seals and cups, so appearing to be in good condition. However laboratory tests, show loss
of headband tension with use or stretching is a more critical factor in deterioration of
attenuation. Comparison of used earmuffs with new earmuffs will reveal this loss of head band
tension, however this is unlikely to be seen as significant damage by the user
Laboratory tests demonstrated a 6dB mean decrease in SNR, above the 4dB derating normally
assumed for earmuffs, with simulated moderate use (equivalent to one month of daily wearing)
or a brief stretching of the headband. 5 out of 16 earmuff users seen would be under protected if
a 6dB reduction in the earmuff SNR occurred.
Damage to earmuff seals is a more visible sign of deterioration, but the effect on attenuation is
unlikely to be as significant as reduced headband tension. In laboratory tests removing an
eighth section of the seal caused a mean drop of 2dB in the SNR.
In cold weather outdoor workers are likely to wear earmuffs over clothing. Laboratory tests
showed the clothing limited the mean earmuff attenuation achieved to between 14 to 21dB.
In most cases where earmuffs were worn with multiple PPE, integral PPE was used. Eye
protection and occasionally dust masks were worn with earmuffs. Laboratory tests showed
small unobtrusive goggles or dust masks gave a mean reduction in earmuff SNR of 2dB
however more obtrusive glasses and goggles could reduce SNR by as much as 10dB.
7.5.2
Earplugs
Laboratory tests showed depth of fit governed the attenuation for push in type earplugs; correct
compression to ensure complete occlusion of the ear canal was the important factor for
compressible foam types.
- 42 -
Custom moulded protectors were not included in the laboratory assessment. Employers and
users seen viewed these as the best available. However employers with a history of using these
reported that not all users found them comfortable.
Compressible foam earplugs were only partially inserted by just over half of the users seen.
Most users were unaware of how to compress the earplug before fitting. Laboratory tests on an
ear simulator showed the earplug SNR can be less than 9dB if incorrectly compress even if fully
inserted into the ear.
Users generally preferred push in plugs, both foam and flange types, as they were easier to fit.
Users were also seen to obtain deeper insertion into the ear canal.
Employers reported providing banded earplugs and ear canal caps but none were seen in use.
Laboratory tests showed that these must be inserted into the ear canal entrance. If held only
against the canal entrance by the band tension they give no protection.
- 43 -
8
RECOMMENDATIONS
Hearing protection is often considered as the first and only solution where a noise risk exists.
Users need to be aware that it is not a simple or reliable solution.
Most employers did not select hearing protection according to the attenuation required. It
would be beneficial if information on the approximate upper and lower sound levels for which
the protector is likely to be suitable was included on the hearing protector packaging and with
any advertising. The information could take account of likely real world attenuation. This
information could be provided in addition to the attenuation data currently provided.
A maximum lifetime, in terms of approximate duration of use, should be provided for all
reusable hearing protection. Hearing protector attenuation deteriorates with use and this
deterioration may not be apparent to the user.
Compressible foam earplugs are generally poorly fitted, as users are generally unaware of how
these should be compressed before fitting, or unaware of the importance of correct compression.
An incorrectly compressed earplug may give virtually no attenuation. Correct use requires a
high level of training, supervision and motivation. Employers providing this type of protection,
and users, need to be aware of these potential problems, and of the existence of alternative types
of earplug such as the foam push-to-fit type.
There needs to be greater awareness of the types of protectors that can assist audibility and
communication.
Earplugs with tracers are required in a wider range of attenuation than is currently available.
There is a need for clothing compatible with correct earmuff fitting for outdoor workers.
Earmuffs worn over conventional hats and hoods can only provide limited attenuation.
- 44 -
9
REFERENCES
Controlling noise at work – Guidance on the Control of noise at work regulations 2005
HSE publication L108
- 45 -
10
10.1
APPENDIX A - INDIVIDUAL PREMISES VISITED
VEHICLE COMPONENT MANUFACTURER
Employs 650 people, 50 to 60 of whom are thought to have daily noise exposures over
85dB(A).
10.1.1
Noise levels
The safety officer reported noise levels from 70 to 95dB. During the visit the measured Aweighted levels reached 91dB. High levels were localised; background levels were below
85dB.
10.1.2
Hearing protection available
Custom moulded earplugs available to staff working in hearing protection zones, after
completion of 6 months employment.
Dispensers provided two types of flanged and one type of compressible foam earplugs
(SNR 25, 30, and 37dB).
Overhead, and neckband earmuffs were available on request (SNR 30 and 31dB)
The safety officer had noted the hearing protection attenuation data provided with the protectors
used, but the attenuation required had not been considered.
10.1.3
Hearing protector and other PPE use seen
Thirteen people were seen working in hearing protection zones where levels were between 85
and 91dB. Eye protection use was also compulsory in these areas.
5 using custom moulded earplugs, all well fitted
4 using compressible foam earplugs, 3 worn well out of the ear, 1 fitted correctly
1 using headband earmuffs, well fitted
3 cleaners were seen in areas without hearing protection. It was said that the hearing
protection zones did not apply to them.
10.1.4
Problems with hearing protection
One person, without custom moulded earplugs, complained the hearing protection made
communication too difficult.
The safety officer said some staff had difficulty using custom-moulded earplugs. Most but not
all custom-moulded earplugs were found to be in a good condition at their annual service.
10.1.5
Training, consultation and maintenance of controls
All staff received training on noise and hearing protection use on induction. A Dupont “Stop
Observation” programme had run since 1979 and involved 70 staff. Areas with levels over
85dB were designated hearing protection zones. Radios and personal stereos were banned.
- 46 -
10.1.6
Health surveillance
Health surveillance is used routinely, and it was claimed no hearing loss had been reported.
10.1.7
Observations/follow-up
This appeared to be a well-controlled environment where the workers accepted hearing
protector use.
Lower attenuation hearing protectors were recommended and guidance was provided on the
selection of hearing protection to avoid over protection.
- 47 -
10.2
METAL FABRICATED BUILDINGS MANUFACTURER
Employs 40 people on shop floor and 10 on off-site building construction.
10.2.1
Noise levels
The company’s noise assessment reported daily noise exposures (LEP,d) between 87 and 95dB,
with noise levels reaching 107dB for some operations. On the day of the visit background
levels were between 77 and 82dB. Measurements of sound levels at the operator’s ear during
welding and grinding were not possible and values reported here are from the company’s risk
assessment.
10.2.2
Hearing protection available
All hearing protection had been assessed against the noise from angle grinding (103dB) using
the octave band method and 4dB de-rating recommended by HSE. The SNR value and
predicted level at the ear from the factory risk assessment are:
Custom moulded earplugs for all staff working in factory and construction. In use for 7
years but only recently supplied to all staff (81dB at ear, SNR value not available).
Dispensers provided compressible foam earplugs (SNR 33dB, 73dB at ear), for visitors
and contractors
Overhead earmuffs for guillotine and angle grinding use (SNR 27dB, 76dB at ear)
Banded earplugs used by people passing through factory area (SNR 23dB, 82dB at the
ear)
In addition flanged earplugs were also seen in use, although these were no longer normal issue.
10.2.3
Hearing protector and other PPE use seen
Sixteen people were noted working where background noise levels were between 81 and 82dB
and during welding operations between 95 and 106dB. Eye and face protection was also used.
4 using custom moulded earplugs, all well fitted
1 using compressible foam earplugs, poorly fitted and worn well out of the ear
3 using headband earmuffs, well fitted
7 using flanged earplugs, well fitted
Foreman using banded earplugs, impossible to see fit.
10.2.4
Problems with hearing protection
One person used earmuffs instead of the custom moulded earplugs as he thought they gave
better protection. The safety officer reported a hearing-aid user had problems with the aid
blocking with fluid when used under earmuffs.
- 48 -
10.2.5
Training, consultation and maintenance of controls
The company safety officer was newly appointed. She had provided training to all staff in the
previous month. Training was conducted in groups of about six, and covered noise control,
fitting of all available hearing protectors, and care of hearing protection. The whole factory
floor was a hearing protection zone. Radios were audible from outside the factory, but turned
off during the visit to the factory floor. The safety officer was consulting with the staff about
removing the radios.
10.2.6
Health surveillance
Health surveillance had been started one month before the visit. No results were available.
10.2.7
Observations/follow-up
The safety officer had only been in post a short time. Noise reduction measures were in
progress and she was conscious of keeping the cooperation of the workers. Hearing protection
had been selected correctly and there was effective training.
Advice on hearing protection suitable for a hearing aid user was requested. A sound restoration
earmuff was recommended with a variable balance control to compensate for different levels of
hearing in each ear, and an equaliser control to vary the frequency response of the reproduced
sound as required.
- 49 -
10.3
BOTTLING PLANT
Employs 94 people in all. Plant operation is normally continuous with four shifts of 20 workers
each.
10.3.1
Noise levels
The plant was shut down during the visit. The safety officer reported A-weighted sound levels
of 85 to 90dB during operation.
10.3.2
Hearing protection available
Dispensers provided two types of types of compressible foam earplugs (SNR 34 and
35dB) on cords. Hand washing was provided by the side of the dispensers.
The maintenance engineers used earmuffs.
The safety officer had noted the attenuation data provided for the hearing protectors, but said the
choice was based on what they had always used rather than considering the attenuation required.
10.3.3
Hearing protector and other PPE use seen
Due to the temporary plant shut down there were no noisy working areas at the time of the visit.
Earplugs were worn despite the shut down. Some staff wore their earplugs by the ear (held
within the hairnet), rather than in the ear. All staff wore hairnets, some wore hooded disposable
boiler suits, and one person wore a face visor.
10.3.4
Problems with hearing protection
Due to hygiene requirements staff used corded disposable earplugs. The safety officer reported
some initial resistance to using hearing protection throughout the plant areas.
10.3.5
Training, consultation and maintenance of controls
All new staff and contractors working on the site receive health and safety induction training.
Staff are instructed to use hearing protection in “mandatory areas” and training is backed up by
a short leaflet of instructions. Day shift leaders do a daily inspection on hearing protector use,
and there are regular safety audits. Areas with continuous noise levels over 85dB are hearing
protection zones.
Noise controls had been implemented in the bottle blowing area where levels were reported to
be 90dB during normal working.
10.3.6
Health surveillance
Health surveillance is used routinely for forklift drivers and is being considered for all staff
working in plant areas.
10.3.7
Observations/follow-up
Hearing protector use was difficult to judge as the plant was shut down. The hearing protection
provided was likely to be over protecting in the noise levels reported during normal working.
Information on correct selection and lower attenuation earplugs was sent to the company health
and safety advisor.
- 50 -
10.4
VEHICLE SERVICING AND REPAIR CENTRE
Dealer providing car sales, with valeting, service and body-shop areas. 10 staff were seen
working in these three service areas.
10.4.1
Noise levels
The safety officer reported noise was from vacuum cleaners, electric polishers, paint spraying,
and air tools such as drills, nut runners and sanders. The company had no information on noise
levels or the daily exposure of staff. A-weighted noise levels of 98dB were measured during the
use of air tools in the service area, and 78dB during use of a vacuum cleaner in the valeting
area.
10.4.2
Hearing protection available
Personal issue of earmuffs for use during noisy activities was claimed. The earmuffs
seen were of the same type with an SNR value of 26dB.
Compressible foam earplugs (SNR 37dB) were available for use by the spray booth
operator.
The attenuation had not been considered in the choice of hearing protection.
10.4.3
Hearing protector and other PPE use seen
Eye protection was seen in use, and the operator working in the paint spray booth used a
respirator.
Only new earmuffs were seen in the service and body shop areas, with no personal
identification. Earmuffs were only used when prompted by the safety officer. There were not
enough earmuffs for personal use.
The paint spray operator could not fit the foam earplugs provided.
10.4.4
Problems with hearing protection
The paint spray operator compressed one end of the foam earplug into a point before inserting.
He was unaware of how to fit the earplug correctly and said he had difficulty inserting them into
his ears such that they stayed in.
10.4.5
Training, consultation and maintenance of controls
New staff receive 2 hours training with the safety officer as part of their induction and all staff
had been given a written copy of the company safety policy to read. The safety officer
considered these actions ensured the company met their legal requirements to provide training
although he admitted they were ineffective. No signs were seen on tools or in work areas
indicating hearing protection was required.
10.4.6
Health surveillance
Health surveillance was provided for body shop staff and noise induced hearing loss had been
detected.
- 51 -
10.4.7
Observations/follow-up
The manager responsible for safety made it clear that he saw health and safety as an
unreasonable inconvenience. He was concerned to meet the law but unconcerned if controls
and safety measures provided were ineffective. He was unaware that effective controls were
legally required.
The paint spray operator could not fit the earplugs provided. Information on alternative
protectors was given. In addition a recorded demonstration of noise induced hearing loss was
provided with advice on improving training on hearing protector use.
- 52 -
10.5
SPECIALIST JOINERY WORKSHOP
Three joiners and the owner/manager used woodworking machinery to manufacture doors and
windows.
10.5.1
Noise levels
There had been no assessment of noise levels or noise exposure. A-weighted levels during use
of machinery in workshop varied from 85 to 92dB at the operator’s ear.
10.5.2
Hearing protection available
Two pairs of damaged sound restoration earmuffs, were the only protectors available. These
earmuffs had damaged seals, broken headband joints repaired with wood glue, and holes in the
muff cups where cable grommets and microphones were missing. The glued repairs impeded
rotation of the muff cups on the headband. Figure 8 shows one pair of the hearing protectors.
Figure 9 Earmuffs used at specialist joinery (premises 5)
No replacement earmuffs were available. The manager said new protectors would not be
provided until he could ensure staff would take good care of them.
10.5.3
Hearing protector and other PPE use seen
The manager used the earmuffs with eye protection while demonstrating machinery in the
workshop.
10.5.4
Training, consultation and maintenance of controls
Staff had chosen the earmuffs provided. The manager was unaware any training on the use of
the hearing protectors was required. There were no signs on equipment or in work areas
advising where hearing protection should be used.
- 53 -
No deliberate noise controls were apparent, but the machinery was located in a separate
workshop and this in itself was probably an effective control.
10.5.5
Health surveillance
Health surveillance was not provided.
10.5.6
Observations/follow-up
This company had very poor hearing protector provision and use. Use of the power tools was
intermittent and no risk assessment had been made to estimate typical daily exposure. It is
possible that use of the power tools was insufficient to give workers an exposure above the
lower action value.
Information on suitable low attenuation earmuffs was provided. The earmuffs at the premises
were exchanged for several pairs of replacement lightweight earmuffs in new condition.
- 54 -
10.6
VEHICLE ACCIDENT REPAIR CENTRE
Family business employing 10 people in the workshop, all working on-site.
10.6.1
Noise levels
Measured A-weighted background levels during visit were 72dB. No noisy tools were used
during the visit.
10.6.2
Hearing protection available
Compressible foam earplugs (SNR 28dB) were available in both corded and non-corded
versions. Earplug dispensers were in the workshop area.
Headband earmuffs were issued for personal use (SNR 27dB)
The owner/manager had considered attenuation in the selection of hearing protection but no
estimate of the actual attenuation provided had been made.
10.6.3
Hearing protector and other PPE use seen
Earmuffs in workshop area were marked with the user name and were in a good but not new
condition. The paint spray operator used earplugs in the booth, and was seen to obtain a
reasonable fit. Face visors, goggles, and safety glasses were also used.
10.6.4
Problems with hearing protection
The manager said his main problem was ensuring the hearing protection was consistently used.
10.6.5
Training, consultation and maintenance of controls
All staff received training on PPE use and safe working of tools on induction from an external
training provider. Tools that should be used with hearing protection were identified. Staff were
required to confirm every month whether they had all the necessary PPE, and six monthly
health and safety meetings were held with staff. The company had a policy to buy quiet tools
and machinery.
The company risk assessment had recorded the sound level of each noisy tool and a simple
sound level meter was used to routinely check sound levels.
10.6.6
Health surveillance
Health surveillance was used, and no hearing loss had been reported.
10.6.7
Observations/follow-up
This company although small appeared to be conscientious and capable of controlling the risks
in their premises. An excellent example of what a small company can achieve.
- 55 -
10.7
IRONWORK RESTORER AND MANUFACTURER
19 people were employed on the shop floor, with occasional off-site working. Noisy activities
were the use of hand tools including hot metal forging, small handheld power tools, power
hammer, paint booth, and vehicle movements.
10.7.1
Noise levels
No assessment had been made of noise exposures. Managers thought daily exposures (LEP,d)
were under 85dB. A-weighted background noise levels of 76 to 78dB were measured during
the visit
10.7.2
Hearing protection available
Two types of headband earmuffs (SNR 27 and 24dB), and integral earmuffs with
helmets for use off-site (SNR value unknown).
Compressible foam earplugs (SNR 28dB).
The attenuation data for the hearing protection had been recorded but no assessment had been
made of the attenuation provided or required.
10.7.3
Hearing protector and other PPE use
Two people were seen using hearing protection. One was wearing earmuffs with the headband
around the neck, rather than over the head; the other was wearing the foam earplugs moderately
well fitted. Hearing protection policy was to use protectors when using noisy machinery or
when in the vicinity of noisy activities.
Operators had earplugs or earmuffs ready for use in their tool kits. Earmuffs were preferred in
higher levels to earplugs, as they were perceived as giving higher attenuation.
Goggles were used during grinding. The painter used a respirator in the paint booth. Safety
helmets with integral protectors were available for use off-site.
10.7.4
Problems with hearing protection
No problems were reported.
10.7.5
Training, consultation and maintenance of controls
New staff received training on the machinery, risks, and safety measures. Signs showed where
hearing protection may be required and managers were said to walk around workshop areas
checking safe working. A register was kept of the personal issue of PPE to ensure regular
replacement. The company has a purchasing policy to buy quiet tools.
10.7.6
Health surveillance
The introduction of health surveillance was being planned at the time of the visit.
10.7.7
Observations/follow-up
This company had by chance selected earmuffs with appropriate attenuation. Information was
provided on lower attenuation earplugs of the push in type.
- 56 -
10.8
PRINTERS
Six people were seen on working on the shop floor.
10.8.1
Noise levels
The company had completed a noise assessment. Two machines were known to give operator
sound pressure levels between 80 and 85dB(A) and noise exposures were estimated to be 81 to
82dB(A). The areas around these machines were marked as hearing protection zones.
Measured sound levels were confirmed as between 80 to 85dB(A) depending on operator
location.
10.8.2
Hearing protection available
Personal issue of headband earmuffs (SNR 25dB)
Compressible foam earplugs (SNR 36dB).
The attenuation of the protectors had not been a factor in their selection.
10.8.3
Hearing protector and other PPE use seen
Only two operators needed to use hearing protection. The compressible foam earplugs were
poorly fitted, the earmuffs were not seen in use.
10.8.4
Problems with hearing protection
Earmuffs were considered uncomfortable when it was hot, and earplugs were preferred for
comfort. Users said there were problems with communication when using the protectors
provided.
10.8.5
Training, consultation and maintenance of controls
No training was provided on hearing protection use. Staff had some awareness of proper use
but not of correct fitting. Signs on machines indicate hearing protection was required.
10.8.6
Health surveillance
Not provided.
10.8.7
Observations/follow-up
During the visit a trial of a simple screen between the two machines where hearing protection
was used showed noise levels could be reduced such that hearing protection was possibly no
longer required. It was also suggested that carpet under and around the two machines would
possibly provide a further noise reduction. No control measures had been tried before by the
company.
Information on low attenuation lightweight hearing protectors was provided.
- 57 -
10.9
CONFECTIONARY MANUFACTURER
Employs over 600 people on single site. The newly appointed company safety officer and one
staff member providing technical support gave information on hearing protection use. No
access was allowed to production areas where hearing protection was used.
10.9.1
Noise levels
The company’s noise assessment showed A-weighted noise levels in production areas varied
from below 80 up to 95dB.
10.9.2
Hearing protection available
Disposable compressible foam earplugs with tracers and cords used during production
(SNR 32 and 36dB)
Engineers use earmuffs – no information on type
The earplugs had been selected because they contained metal tracers and so were suitable for
food manufacture. Attenuation provided had not been a factor in the choice.
10.9.3
Problems with hearing protection
Most staff in the production areas do not need to use hearing protection continuously but even
so earplugs were said to be uncomfortable. It was said corded earplugs with tracers were not
available with low attenuation, and this was confirmed by a later web search. Earmuffs were
not used, as conditions were said to be too hot and dusty during production. The company
wanted to use banded earplugs but none were available with the fixed earpieces necessary for
food manufacture.
10.9.4
Training, consultation and maintenance of controls
New staff received safety training as part of their induction.
10.9.5
Health surveillance
No hearing tests were carried out.
10.9.6
Observations/follow-up
This company needed to find lower attenuation earplugs with tracers. Information on a tracer
earplug with an SNR value of 24dB was found (JSP Megaplug) but no lower attenuation
earplugs were available.
- 58 -
10.10
JOINERY FACTORY
Employs 82 people, in three large workshop areas. The factory has a high volume, mechanised
production with workers having little variation in activity.
10.10.1
Noise levels
A-weighted noise levels reported by company were up to 105dB, measured noise levels during
the visit were between 85 and 100dB. Staff work an 8.5 hour day. Daily exposure is likely to
correspond to the sound levels at the workstations due to the lack of variation in activity.
10.10.2
Hearing protection available
Push in foam earplugs with a rigid centre (SNR 23dB)
Flanged earplugs (SNR 30dB)
Headband earmuffs (SNR 30dB) (covers are available for use when it is hot).
A hearing protector manufacturer had carried out a noise assessment for the company. The
hearing protection available was selected as a result of the assessment.
10.10.3
Hearing protector and other PPE use seen
All working areas were made available.
The foam push in earplugs were the most popular choice. In general these were worn
across the pinna rather than in the ear canal and so provided no protection.
Flanged earplugs were generally well fitted
Earmuffs were well fitted
No one was seen working in the factory areas without hearing protection
10.10.4
Problems with hearing protection
The production manager said staff were unhappy about the imposition of hearing protection as it
prevented them hearing their radios. Clearly there was little cooperation with the use of hearing
protection at this site. The production manager also recognised this non-cooperation was linked
to the failure of the company to plan or implement any noise controls.
10.10.5
Training, consultation and maintenance of controls
All staff had received training from the hearing protector manufacturer on the use of hearing
protection and the risks had been explained for all areas of the factory.
Noise measurements had been carried by the hearing protector manufacturer supplying the
hearing protection used, but no full noise assessment. There were no noise controls, but it was
planned to reduce noise in the factory by removing the workers’ radios.
- 59 -
10.10.6
Health surveillance
Hearing tests are not provided for staff.
10.10.7
Observations/follow-up
This company had poor relations with the workers over the issue of noise control. No action
had been taken to control the noise other than the intention to ban the use of radios. The
workers were clearly expressing their dissatisfaction by wearing hearing protection incorrectly.
The management did not consider the incorrect wearing of the protectors as a problem that need
concern them.
Noise measurements were made during the visit to provide an assessment of noise exposures.
Following the visit information was provided on companies that might provide some control
solutions for their woodworking machinery.
- 60 -
10.11
MANUFACTURER OF SMALL PLANT MACHINERY
Employs 125 people on the shop floor with 95 working in noisy areas. Noisy activities are cold
fabrication and welding of metal sheet and tube.
10.11.1
Noise levels
The company’s noise assessment reports A-weighted noise levels from below 80 up to 92dB in
production areas. These sound levels were confirmed by measurements on the day of the visit.
10.11.2
Hearing protection available
Two versions of push in foam plug with a rigid centre (SNR 27 and 29dB)
Compressible foam plug (SNR 28dB)
Flanged plug (SNR 30dB)
Dispensers for the foam earplugs were at the entrance to the work areas. The hearing protector
attenuation data had been noted but the attenuation required or provided had not been
considered.
10.11.3
Hearing protector and other PPE use seen
In areas where sound levels were between 73 to 75dB
5 wore the foam earplugs with the rigid centre, 3 with a good fit, 2 with a poor fit
2 wore flanged earplugs with a moderately good fit
2 wore the compressible foam earplugs fitted poorly.
In areas where sound levels were between 84 to 92dB
7 wore the foam earplugs with the rigid centre fitted well, 2 had a poor fit
2 wore the compressible foam earplugs fitted well
2 wore the flanged earplugs fitted well
10 were not using hearing protection
10.11.4
Problems with hearing protection
Hearing protection was being used where there was no risk because hearing protection zones
were too extensive. In one area where levels were above 85dB hearing protection was not being
used.
10.11.5
Training, consultation and maintenance of controls
Safety training was provided as part of the induction and every two months by a consultant.
Whole buildings were marked as hearing protection zones because they contained areas where
- 61 -
levels were in likely to be above 80 to 85dB. An external facilitator audited a part of the factory
once a month. Automation of processes had reduced the noise exposure of staff.
10.11.6
Health surveillance
Audiometry had been recently introduced for 85% of the staff. No results were available.
10.11.7
Observations/follow-up
This company had created over extensive hearing protection zones, requiring hearing protection
to be used where there was no risk to hearing.
Information on suitable types of low attenuation hearing protectors was provided.
- 62 -
10.12
SHEET METAL WORKSHOP
Employs four to five people on the shop floor, three were seen on the day of the visit. The
workshop had a modern punch press, laser-cutting machine, and a press brake. Most noise
exposure was from the use of hand hammers, small hand grinders, and spot welding.
10.12.1
Noise levels
A-weighted background noise levels were 77dB mostly arising from the continual operation of
the punch press. No noise assessment had been made; noise exposures (LEP,d) were estimated to
be between 80 to 85dB on the day of the visit.
10.12.2
Hearing protection available
Push in foam earplugs with rigid handle (SNR 35dB)
Headband earmuffs (SNR 28dB)
The attenuation of the hearing protectors had not been a factor in their choice.
10.12.3
Hearing protector and other PPE use seen
The push in foam earplugs were well fitted by all staff seen in workshop.
Earmuffs were only seen by a workstation that was not in use. These were dusty but
otherwise in good condition.
10.12.4
Problems with hearing protection
The manager and staff were happy with the hearing protection they were using.
10.12.5
Training, consultation and maintenance of controls
No training had been given to staff. The staff seen all said they had experience of using hearing
protection from previous employment.
10.12.6
Health surveillance
Hearing tests are not provided for staff.
10.12.7
Observations/follow-up
This company had staff who were already aware of the noise risks of the tools they were using.
There were good relations between the manager and the staff and they appeared to take safety as
a joint responsibility.
Earplugs with an SNR under 20dB were recommended.
- 63 -
10.13
COUNTY COUNCIL
Hearing protection is used in highway maintenance and construction, and countryside services
(using chain saws, brush cutters, strimmers, and a mobile wood chipper). Only an interview of
council safety staff was made, there were no site visits.
10.13.1
Hearing protection available
Combination visor, helmet and earmuffs used by countryside staff (SNR value not
available)
Banded earplugs (SNR 23dB) used by highway maintenance
Headband earmuffs (SNR 26dB) used by highway maintenance
Low to mid attenuation protection for highway maintenance staff had been selected because of
their need to hear traffic movement.
10.13.2
Problems with hearing protection
Hearing approaching vehicles is a major concern for highway maintenance staff using hearing
protection. The view of staff was “I’d rather be deaf than dead”.
Enforcement or supervision of hearing protector use by outdoor teams was considered to be
difficult.
One individual had reported problems with dermatitis when using hearing protection.
The safety staff interviewed wanted HSE to provide simpler information and aids for workers
using hearing protection.
10.13.3
Training, consultation and maintenance of controls
Demonstrations on how to fit hearing protection and road worker noise awareness training had
been provided in the previous 12 months. New starter and refresher training was in preparation.
There were quarterly joint management/ TU health and safety inspections.
The council has a policy to buy low vibration equipment, but no similar purchasing policy
applies to noise.
10.13.4
Health surveillance
A voluntary scheme plus mandatory checks for individuals where there is a cause for concern
has existed for three years. Noise induced hearing loss had been found.
10.13.5
Observations/follow-up
Flat response and sound restoration hearing protectors were recommended for the highway
maintenance teams where audibility of passing traffic is a prime concern. During 2008 the
council trialled a range of these protectors.
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10.14
PRESSURE SYSTEM COMPONENT MANUFACTURE
Hot-metal pressing and cold machining occurred in the manufacturing area. Seven workers were
seen in the manufacturing area, seven in the warehouse and packaging area.
10.14.1
Noise levels
In manufacturing areas A-weighted background noise levels were between 83 and 87dB. Sound
pressure levels at work stations were between 89 and 98dB. In packaging areas operator sound
pressure levels were 88 to 90dB.
10.14.2
Hearing protection available
Compressible foam plug (SNR 28dB)
Flanged earplugs (SNR 30dB)
Headband earmuffs (SNR 27dB)
The attenuation of the hearing protection provided had been noted but no assessment of the
protection provided or required had been made.
10.14.3
Hearing protector and other PPE use seen
Hearing protection in use at all noisy locations. Earmuffs and earplugs all worn correctly.
10.14.4
Problems with hearing protection
No problems reported
10.14.5
Training, consultation and maintenance of controls
All staff received training during their induction period. Manufacturer’s instructions were
provided for fitting hearing protection, and instructions on the care of hearing protection was
also provided. Hearing protection zones were clearly marked.
Only limited noise controls had been trialled on an auto-bagging machine. Simple controls to
prevent impact noise and compressed air discharge noise were absent.
10.14.6
Health surveillance
No information was available.
10.14.7
Observations/follow-up
Simple noise controls to prevent impact noise, and reduce compressed air discharge noise were
recommended. HSL made a follow up visit to assess hand-arm vibration exposure and possible
controls to reduce both vibration and noise at the request of HSE.
- 65 -
10.15
CEMENT WORKS
Employs around 150 people in the production areas, including contractors. This large site has
risks from both noise and dust in its working areas.
10.15.1
Noise levels
A-weighted noise levels measured on site were between 89 to 94dB in working areas.
Measured LC – LA values were between 8 to 9dB, confirming the noise was dominated by low
frequencies .
10.15.2
Hearing protection available
Compressible foam plug (SNR 28dB)
Flanged earplugs (SNR 30dB)
Push in foam plug with rigid handle (SNR 38dB)
Two types of helmet mounted headband earmuffs (SNR 30 and 34dB)
Trialling custom moulded earplugs
Two types of banded earplugs (SNR 23 and 27dB)
All hearing protectors were available from the site store and earplugs were also available from
dispensers at the entrances to site buildings. The HSE hearing protector calculator was used
when selecting hearing protection.
10.15.3
Hearing protector and other PPE use seen
Staff were seen working wearing eye protection, dust masks, and helmet mounted earmuffs.
The earmuffs were dusty but in good condition. No other hearing protection was seen in use.
10.15.4
Problems with hearing protection
Some staff disliked using earmuffs because of the dusty environment.
10.15.5
Training, consultation and maintenance of controls
Toolbox talks were given every six months on safety issues, and more detailed information was
provided for supervisors and managers via HSIP implementation procedures. Supervisors were
also expected to check on hearing protector use on the site.
A noise and dust survey was conducted every three years.
10.15.6
Health surveillance
Audiometry had been included in health surveillance from 2007, and hearing loss had been
found. The company was using the results to re-evaluate control measures.
10.15.7
Observations/follow-up
This was a large site with a number of risks. Risks appeared to be well controlled, but the safety
officer was in some cases unsure whether controls were adequate.
- 66 -
10.16
OUTDOOR WORKERS – RANDOM ENCOUNTERS
Outdoor workers seen using hearing protection were approached on a opportunistic basis. The
sound pressure levels during noisy work were measured on two of these occasions and the
workers were asked about hearing protection use. The self-employed gardener was seen on a
regular basis and so the consistent hearing protector use was confirmed.
10.16.1
Noise levels
Two grounds maintenance workers employed by service company using petrol
strimmers giving a measured A-weighted noise level of 95dB
Self-employed gardener using petrol mower and petrol strimmer (no noise
measurements were possible at the time)
Community punishment team using three petrol strimmers and hand tools (no noise
measurements were possible at the time)
Two road maintenance staff using road breaker and cut-off saw (97 and 107dB
respectively).
10.16.2
Hearing protector and other PPE use seen
Grounds maintenance - helmet, visor and muff combination (SNR value unknown) well
fitted and said to be comfortable. Use of PPE required by employer when using
strimmers.
Gardener - Overhead earmuffs in good condition (SNR 35dB) chosen following
guidance from a health and safety advisor. Wearing consistently when using noisy
machinery.
Community punishment team – face visors were worn but no hearing protection was
being used. The team supervisor had only one pair of earmuffs available for the whole
team. The community punishment management said training was provided to all team
members before they started work.
Road maintenance – Both workers wearing overhead earmuffs (see Figure 10).
o
Worker 1 using roadbreaker (noise level 97dB) wearing light-weight earmuffs
(SNR 23dB) over cap, eye protection and jacket hood. Earmuffs had poor
tension and damaged seals.
o
Worker 2 using cut-off saw (noise level 107) wearing mid-weight earmuffs
(SNR 31dB) over fleece hat, eye protection, and facemask.
- 67 -
Figure 10 Road maintenance workers wearing hearing protection over clothing
and other PPE
10.16.3
Problems with hearing protection
The road maintenance workers were seen on a cold day. The earmuffs they had available could
not be worn under the hoods and hats they needed to wear. These workers also highlighted the
problem that off site workers do not always have advice on or access to suitable hearing
protection because of lack of supervision.
The community punishment team said they had no say in the PPE they were required to use and
its condition. The earmuffs provided could not be fitted correctly with the visors used. The
team had refused to use the earmuffs because other people had worn them. The supervisors were
reluctant to stop those refusing to use the PPE from working as this could require them to be
returned to court.
- 68 -
- 69 -
Published by the Health and Safety Executive
07/09
Health and Safety
Executive
Real world use and performance
of hearing protection
This report considers the effectiveness of hearing
protectors in everyday work situations. The study
reported here was undertaken in two parts. The first
consisted of interviews with employers to discuss
management of noise and hearing protector use,
and on site observation of hearing protector use.
The purpose of these visits was to see:
n
n
n
n
how well hearing protection was used;
the training provided;
the use of other PPE and equipment that may
limit attenuation;
behavioural factors affecting use, taking into
account the noise exposure of employees
and the environment in which the hearing
protection is worn.
The second part was objective laboratory
measurements of hearing protector insertion
loss. The purpose of these measurements was
to quantify the reduction in protection due to
poor fitting or maintenance for a range of hearing
protectors. Earmuffs were tested using the MIRE
(microphone in real ear) method while earplug
insertion loss was measured using a head and torso
simulator with a simulated pinna and ear canal.
This report and the work it describes were funded
by the Health and Safety Executive (HSE). Its
contents, including any opinions and/or conclusions
expressed, are those of the author alone and do not
necessarily reflect HSE policy.
RR720
www.hse.gov.uk
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