Conference PaperPDF Available

Noise Source Identification and Assessment of two Noise Controls for Jack Hammers

Authors:
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Portland, Oregon
NOISE-CON 2011
2011 July 25-27
Noise Source Identification and Assessment of two Noise
Controls for Jack Hammers
Edward Zechmanna)
National Institute for Occupational Safety and Health
4676 Columbia Parkway C-27
Cincinnati, OH 45220
Andrew Hemmelgarnb)
Charles Haydenc)
Abstract
Jack hammers are among the most widely used and noisy pieces of equipment in construction,
roadway, mining, and utility maintenance. Noise emitted from jack hammers can cause noise
induced hearing loss which is most effectively prevented using source control of noise. To
advance engineering control of noise, the major noise sources of four jack hammers were
identified then the effectiveness of two noise controls: a jacket enclosing the tool body and a
bellows device enclosing the chisel were assessed. All testing was conducted at the National
Institute for Occupational Safety and Health Laboratories in Pittsburgh, PA. Jack hammers were
tested while chipping concrete. Three of the jack hammers were electric and one was pneumatic
powered. Noise source identification was conducted in a hemi-anechoic chamber using a beam
forming array model 8608 (B&K, Norcross, GA). The chisels and interaction of the chisels with
the concrete and the exhaust ports were identified as major noise sources. The two noise controls
were assessed using sound power measurements in accordance with ANSI S12.53/PART 2/ISO
3743-2 using a B&K pulse system. The two noise controls were found to have no more than 4
dB of noise reduction.
Disclaimer: The findings and conclusions in this report are those of the author(s) and do not necessarily represent
the views of the National Institute for Occupational Safety and Health (NIOSH). Mention of company names of
products does not constitute endorsement by the Centers for Disease Control and Prevention (CDC), NIOSH.
1 INTRODUCTION
Jack hammers, used to break up concrete, asphalt, and stone during roadwork, refurbishments,
construction of foundations, or to gain access to underground utility lines are among the most
widely used pieces of equipment on construction sites and roadway or utility maintenance jobs.
Most persons are well acquainted with the sound of jack hammer operations. Whether walking
along a city street or sitting comfortably in one’s home, the noise emitting from a jack hammer
operation can be easily heard by persons in the surrounding area and beyond. Not only is the
noise loud, but the intermittent impulsive nature of the noise can further exacerbate the hearing
a) Email: EZechmann@cdc.gov
b) Email: AHemmelgarn@cdc.gov
c) Email: CHayden@cdc.gov
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hazard and annoyance. New York City’s Department of Environmental Protection states that,
“…Jack hammers are the number one environmental noise issue for construction in NYC.”
Jack hammers regularly operate at or above an eight hour time-weighted average (TWA) of 90
dBA. The 1 minute time averaged exposures can exceed 110 dBA.1-3 Such high levels can
cause permanent hearing damage to unprotected workers in less than two minutes of exposure.
To assess noise levels, identify acoustical characteristics, and examine the effectiveness of two
noise controls for jack hammers, NIOSH researchers conducted a set of experiments at the
Office of Mining safety and Health Research (OMSHR) laboratory in Pittsburgh. Two
measurement techniques were used: beam forming and sound power measurements. Beam
forming was used to identify noise source characteristics. Sound power data was collected in
accordance with ANSI S12.53/PART 2/ISO 3743-24.
This report presents the sound power levels, noise source identification analysis, and the
effectiveness of two existing noise controls. The measured noise levels will be added to the
NIOSH power tools database to further expand the database’s use in providing relevant noise
level information to tool purchasers and manufacturers. Further, hearing conservation
professionals can use the noise level information to select appropriate hearing protection.5-9 The
database website is given in reference 7.
2 METHODS
2.1 Evaluation Criteria and Occupational Exposure Limits
The noise control must reduce the sound power level by 3 dB to be considered to be significant,
since the measurement uncertainty is likely greater than 3 dB. The OSHA occupational exposure
limit is a TWA of 90 dBA. The NIOSH recommended exposure limit is a TWA of 85 dBA. A 3
dB reduction in the sound power level will be considered successful; however, a 3dB reduction
in sound power may or may not result in a reduction in the exposure level. Analysis of noise
exposure data is required before inferring a reduction in noise exposure. This paper will
therefore be limited to reporting reductions in sound power levels. Evaluating the noise controls
for reduction in noise exposures will be the subject of a future paper.
2.2 Jack Hammers
Four hand held jack hammers were tested, each from a different manufacturer. The sizes ranged
from small (31 lbs) to large (71 lbs). Table 1 shows the details of the four different jack
hammers. Three of the jack hammers were electric powered while the fourth was pneumatic.
Manufacturer
Model #
Weight
(lbs)
Impact Force
(ft-lbs)
Blows per
minute (bpm)
Power
Source
Hilti
TE 1500-AVR
31
22
1620
Electric
Makita
HM1810
71
46
1100
Electric
Bosch
11335K
38
34
1300
Electric
Chicago Pneumatic
CP 1210 S
48
35
1400
Pneumatic
Table 1 – Specifications for the jack hammers under test.
2.3 Chisels
To assess the effect of chisel type on sound level of the jack hammer six chisels of different
design were used in a comparative study. The most common hardened steel chisel types found
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on jobsites were tested. The Bosch and the Brunner and Lay chisels were interchangeable with
the Makita, Bosch, and Chicago Pneumatic, but not with the Hilti. The Hilti brand chisels were
only compatible with the Hilti jack hammer.
Model #
Dimension
Description
HS2163
1 3/8 x 20
Narrow Chisel
HS2164
3 x 20
Wide Chisel
A33024
1 1/8 x 30
STD 3" Chisel
B30800
1 1/8 x 20
Concrete Buster
TE-SP SM 36
7/8 x 14
Pointed Chisel
TE-SP FM 36
1 1/4 x14
Flat Chisel
Table 2 – Specifications for the jack hammer chisels under test.
2.4 Noise Controls
2.4.1 No Racket Jacket
The No Racket Jacket (Zo-Air, Holbrook, NY) is a cylindrical wrap encasing the body of the
jack hammer from below the handles. The jacket is made of three layers of neoprene rubberlike
material sewn together, open at one end and closed off at the other with a 1-inch thick rubber
bottom. The jacket opens and closes along its length for ease of fitting over the jack hammer.
The opening along its length uses a 4-inch wide industrial Velcro strip. The open end of the
jacket uses additional Velcro straps to secure the jacket to the top of the jack hammer. The
jacket weighs approximately 2 lbs. and can be installed in about 30 seconds. Sound power tests
conducted by the New York City Department of Environmental Protection using a pneumatic
jack hammer showed an approximate 5 dBA reduction at the ear of the operator, allowing double
the exposure time as established by the U. S. Occupational Safety and Health Administration in
noise exposure standards at 29 CFR 1910.95.10-12 Figure 1 shows the No Racket Jacket attached
to a Chicago Pneumatic jack hammer.
2.4.2 Bellows Device
Another noise control tested was the bellows device. The bellows, constructed like basic flexible
ductwork, was 0.032 “thick with a 2.25” ID and 3.75” OD and made of silver aluminum
fiberglass (International Bellows and Covers Inc. Clayton, OH). The bellows device was
retrofitted by researchers to fit over the chisel and attached to the bottom of the jacket. Figure 1
shows the bellows device attached to a Chicago Pneumatic jack hammer.
Figure 1 – No Racket Jacket and Bellows attached to Chicago Pneumatic jack hammer.
Bellows Device
No Racket Jacket
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2.4 Test Methods
Two types of measurements were conducted: beam forming array noise source identification and
sound power level measurements.
2.4.1 Unloaded Testing
The jack hammer was suspended by bungee cords 0.5 meters off the floor using a large hoist.
The Makita, Bosch, and Chicago Pneumatic jack hammers were equipped with the Bosch
HS2163 Narrow Chisel and the Hilti jack hammer was equipped with the Hilti TE-SP FM 36
Flat Chisel. The electric jack hammers were nominally powered at 120 Volts and the pneumatic
jack hammer had a nominal air supply pressure of 90 psi. The jack hammer ran continuously for
several minutes as 3 sound power measurements each of 50 seconds were acquired.
2.4.2 Loaded Testing
There is not a standard or test code in the US for testing the noise of jack hammers. The
European Union Directive 2000/14/EC of the European Parliament and of the Council, Official
Journal of the European Communities published a method for measuring the sound power of jack
hammers, but the method is discordant with actual jack hammer use. This recommended test
method is unable to examine the interaction between the chisel and the workpiece and therefore
deemed not relevant to establishing operator noise exposure.13,14 For this reason, the authors of
this paper devised a test method enabling the measurement of noise level with a jack hammer in
actual use.
In the method employed in this study, the jack hammers are operated fully loaded on a test stand
constructed from 20x26x6 inch thick concrete blocks having a compressive strength of 5000 psi
(Quality Concrete, Pittsburgh, PA). The concrete had a nominal curing time of 28 days. The
concrete blocks were stacked in a 3 by 3 grid as shown in Figure 2. The concrete test stand was
built over a 3x3 grid of rubber acoustic ballistic tiles (New Century Northwest LLC, Eugene,
OR) as shown in Figure 3. The 24x24x1.5 inch rubber tiles weighed about 29 lbs each and had a
stiffness of 70 Shore A. The rubber tiles protected the floor and damped the vibrations. During
testing, the jack hammer operator stood on top of the test stand and chipped through the concrete
of the first layer of concrete blocks. The operator was instructed to allow the weight of the jack
hammer to do most of the downward work and to apply only as much downward force on the
jack hammer as was necessary to control the tool.
Figure 2 – A 3 x 3 grid of concrete blocks stacked 3 high.
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Each jack hammer was tested in the loaded condition without noise controls to establish a
baseline sound power. The Makita, Bosch, and Chicago Pneumatic jack hammers were tested
while chiseling off chunks of concrete using the Bosch and Brunner and Lay chisels. The Hilti
jack hammer was tested using the Hilti chisels. The four jack hammers were tested with the No
Racket Jacket only and with both the No Racket Jacket and bellows. Bellows only was not
tested since the bellows was attached to the No Racket Jacket.
Figure 3 – A 3 x 3 grid of shredded rubber acoustic ballistic tiles. The concrete blocks were
placed on top of the acoustic ballistic tiles.
A triangular force plate (Model HET900T-300, Advanced Mechanical Technology Inc.,
Watertown, MA) was used to measure the feed force through the reaction at the tool operator’s
feet. Each vertex of the triangle has a triaxial force sensor. The hammer operator stood on top
of the force plate. Figure 4 shows the triangular force plate used to measure feed force.
Figure 4 – Triangular force plate model HET900T-300 on top of the concrete pile.
2.4.3 Noise Source Identification
Noise source identification was performed in the hemi-anechoic chamber using the Brüel & Kjær
® Type 8608 beam forming slice wheel array consisting of a 2 meter diameter wheel having 84
Force Plate
Operator’s Feet
Chisel
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microphones spaced around the wheel. The array was placed nominally 2.3 meters from the
chisel/concrete contact point. After each 10 second data acquisition test run, a camera mounted
on the beam forming array acquired a high resolution image to be mapped to the beam forming
sound map during post processing.
The PULSE beam forming software calculated time delays from the 84 microphone locations to
provide noise source location. The software plots a time recording, then the user selects a time
interval to analyze. The analyzed data is plotted in a spectrogram and the user selects a
frequency range for a detailed noise source color map. The beam forming software
reconstructed the sound pressure at each point in the plane of the jack hammer with an overlaid
color map.15
For each acquisition test run, a 1-2 second time block of relevant data was analyzed between
800-6000 Hz. For each frequency in the FFT, there is a camera image with an overlaid sound
map. Note the camera captured only one image at the end of the 10-second data acquisition
period and therefore the typical 2-second block of time data analyzed usually did not match up
perfectly with the image. However, the time-lagged sound map overlaid onto the image still
provided sufficient information to identify noise sources.
2.4.4 Sound Power
The sound power levels of the jack hammers were measured in both the loaded and unloaded
conditions in accordance with ANSI S12.53. The chamber was equipped with 15 microphones
set in accordance with the ANSI S12.51/ISO 3741 standard. Data acquisition was done using a
Brüel & Kjær ® PULSE Multi-Analyzer System. For each day of testing, all microphones were
calibrated, the background sound level was measured, and reference sound source measurements
were gathered. The data in the loaded condition were acquired for 5 seconds after allowing the
tool to run for 3 seconds, allowing the sound field in the chamber to become diffuse. For each
test setup, measurements were repeated three times. The average of the three sound power values
was taken as the sound power value for that test set up.
3 RESULTS
3.1 Noise Source Identification
Figures 5 through 9 show color maps of the images of sound pressure levels overlaid on the
photo of the jack hammer just after operation. The colors indicate major noise sources, from
where the sound came. These color maps do not accurately represent the overall levels. The
main features of the images are the jack hammer, tool operator, test stand of concrete blocks, and
noise level map.
Frequency specific sound mapping provides both magnitude and source indication. As shown in
Figure 5, the low frequency content (< 2000 Hz) is 10-15 dBA lower in magnitude than the
higher frequency emissions. The low frequency emissions are primarily from the concrete
blocks or test setup.
Figure 6 shows the sound map at 5664 Hz. Note the sound level magnitude of greater than 90
dBA and the location being at the chisel/workpiece location.
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Figure 5 – B&K beam forming array software output provides the narrow band spectrum
(bottom left) to indicate insignificant noise emissions at the lower frequencies and that the lower
frequency noise emission is primarily from the test setup (vibration from the concrete blocks).
Figure 6 – Across the frequency spectrum, the highest noise levels are emitted at the
chisel/workpiece interaction location.
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Figure 7 shows the sound maps for the four jack hammers as tested without noise controls. The
sound map is shown for the whole frequency range of 800-6000 Hz. Figure 8, operation with
the No Racket Jacket shows a similar sound profile as Figure 7. Figure 9, operation with both
the No Racket Jacket and the bellows shows the sound coming out of the top of the jacket and
towards the operator. This could be an additional noise source and or could be sound channeled
by the Bellows and No Racket Jacket. For Figures 7-9 the jack hammers are from left to right
the Hilti, Makita, Bosch, and Chicago Pneumatic.
Figure 7 – No controls. The chisel/workpiece location is the primary noise source.
Figure 8 – With No Racket Jacket. Again, the chisel/workpiece location is the primary noise
source.
Figure 9 – With both No Racket Jacket and Bellows. The chisel/workpiece area and the open
area above the No Racket Jacket are the primary noise sources.
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3.2 Sound Power Level
The jack hammers were tested with a feed force ranging from 10 to 15 lbs. While the feed force
gathered from the force plate is not used directly in the sound power level calculation, it is
nonetheless valuable to monitor and report to demonstrate a level of consistency in the jack
hammer operation. Figure 10 shows the A-weighted sound power level (dBA ref. 1 picoWatt)
test results for loaded testing with and without noise controls. Figure 11 shows the A-weighted
sound power level test results for unloaded testing and loaded testing with various chisel types
without any noise controls.
Figure 10 –Comparison of the measured sound power level with and without noise controls
Figure 11 – Test configuration vs. sound power level provides indication of unloaded condition
and loaded condition for various chisel types in effecting noise emission levels.
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The Hilti jack hammer had the lowest sound power in both the unloaded and loaded conditions.
The Chicago Pneumatic had the highest sound power in the unloaded condition and the Bosch
had the higest sound power in the loaded condition. The sound power level of the Hilti remained
nearly the same, little influenced by chisels, or noise controls. For the other jack hammers, the
No Racket Jacket provided up to 1 dB of noise reduction and the combination of the No Racket
Jacket and bellows device provided up to 2 to 4 dB of noise reduction. The long wide chisel
induced the highest sound power for all chisel types. The differences in the mean between the
loaded no controls and the No Racket Jacket and Bellows is generally less than the measurement
uncertainty; however, the difference in the means is significant at the 20% confidence level with
a two tailed t-test with unknown variances
4 DISCUSSION
A review of the more than 8000 pages of sound maps at discrete frequencies shows similar
results for noise source location. In all of loaded testing of the combinations of jack hammers,
chisels, and noise controls, the noise source locations are very similar. This can be seen in
Figures 7-9 where the primary noise source is from the chisel/work-piece contact point.
From Figures 5-6, it is seen that the highest levels of noise are being emitted at frequencies
greater than 2000 Hz (see the narrow band spectrum at the lower left of the figures). The noise
emissions from the low to mid frequency range come primarily from the concrete blocks
vibrating against one another during testing. Fortunately, the noise emission levels from this
frequency range are low (< 80 dBA). In comparison, emissions in the high frequency range (>
2000 Hz) are much greater (>85 dBA). In this frequency range (> 2000 Hz), the sound maps
clearly identify the chisel to concrete contact point as the location of the noise source. The
ringing of the chisel is audible during the tests. Unfortunately no noise controls for “chisel
ringing” were tested.
For the electric jack hammers, the loaded sound power levels were up to 20 dBA greater than the
unloaded sound power levels for the same combination of jack hammer and chisel and noise
control. Note again the loaded tests – and controls on and off - were accomplished using the
short narrow tipped chisel.
For the pneumatic jack hammer, no significant sound power level differences were observed
between the loaded and unloaded conditions, or between operations with or without noise
controls. For the pneumatic jack hammer the types of chisels made negligible differences. The
pneumatic jack hammer itself is likely a very significant noise source in addition to the chisel to
concrete interaction.
Except for the pneumatic jack hammer, a 1-4 dB reduction in sound power level was observed
when both jacket and bellows were used. In general, the shorter and narrower tipped chisels
tended to produce lower sound power levels. This is in line with the finding that the most
significant noise emissions are emitted by the chisel/work-piece interaction and the ringing of the
chisel. However there are other noise sources that need to be understood more completely.
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5 RECOMMENDATIONS
The No Racket Jacket noise control design should be upgraded to enhance its noise absorption
properties. This should also include closing off the top of the jacket with a barrier and internal
sound absorbing material. Current jack hammer noise control technology should focus on
designing the chisel for quiet and/or providing a sound absorptive sheath over the chisel.
For the pneumatic jack hammer the little difference in the no-load condition and actual operation
noise level suggests that chisel ringing and air-pulsation noise are very large. Properly designed
mufflers at the air intake and exhaust may help.
The bellows may or may not be designed as an integral part of the noise jacket technology, but
the bellows by itself would have to be configured to attach readily to a variety of jack hammers.
Further, the bellows could obstruct the operator’s sightlines to the chisel/work-piece location. A
trained operator may not be affected by this as they would simply change their visual cue to the
outer end of the bellows. As long as they were not attempting to make clean finish breaks in the
work-piece, the less precise visual cue should be appropriate.
Adding damping to the chisel is likely to reduce the noise coming from the chisel; however, to
accomplish a significant over noise reduction there may be other noise sources to control.
Further testing should be accomplished to examine the dampened steel chisel design. The design
could be as simple and inexpensive as mounting a rubber sleeve on the chisel. Simple impact
testing using mounted rubber sleeve showed a substantial qualitative difference in “chisel ringing”
noise emissions.16,17 Testing of chisel damping will help to understand the noise sources.
6 ACKNOWLEDGEMENTS
Special thanks to James Thompson, Shawn Peterson, Kevin Schuster, Patrick McElhinney, and
Jessie Mechling of the NIOSH Pittsburgh OMSHR for providing access to their facilities,
equipment, assistance, and operating the machinery. Thanks to Tony Frazer of B&K for
providing invaluable assistance in gathering the beam forming array data.
7 REFERENCES
1. Hattis, Dale(1998) 'Occupational Noise Sources and Exposures in Construction Industries',
Human and Ecological Risk Assessment: An International Journal, 4: 6, 1417-1441
2. Neitzel, Richard , Seixas, Noah S. , Camp, Janice and Yost, Michael(1999) 'An Assessment
of Occupational Noise Exposures in Four Construction Trades', American Industrial Hygiene
Association Journal, 60: 6, 807-817
3. “Criteria for a recommended standard: occupational noise exposure (revised criteria)”,
National Institute for Occupational Safety and Health, DHHS (NIOSH) Pub No. 98-126,
NIOSH, Cincinnati, OH, (1998)
4. ANSI/ASA S12.53 Part 2-1999 ISO 3743-2:1994 (R2009), Acoustics — Determination of
sound power levels of noise sources using sound pressure — Engineering methods for small,
movable sources in reverberant fields — Part 2: Methods for special reverberation test
rooms, National Adoption of International Standard ISO 3743:1994 (Acoustical Society of
America, New York, 1999)
Page 12 of 12
5. Charles Hayden and Rickie Davis, “Production of a Noise Level Database of Power Tools
Used in the Construction Industry,” DHHS, PHS, CDC, NIOSH, Cincinnati, OH, Report No.
EPHB 283-03, Nov. 2003
6. Hayden C., Zechmann E., Verma R., “Powered Hand Tools Sound Power Level Database,”
Dept. Health and Human Services, Public Health Service, Centers for Disease Control and
Prevention, NIOSH, August 2005
7. NIOSH Power Tools Online Searchable Database
http://wwwn.cdc.gov/niosh-sound-vibration viewed 29 April 2011
8. Zechmann E. and Hayden C., “Sound Power Measurement Techniques for Powered Hand
Tools,” INCE Conference Proceedings, Minneapolis, Minnesota, October 2005
9. Zechmann E, Hayden CS. “Comparison of Sound Power Levels of Portable Powered Hand
Tools in the Loaded and Unloaded Condition”. INCE Conference Proceedings, Honolulu, HI,
December 2006
10. Eric Zwerling, Charles Shamoon, “Proactive Regulation Engenders Creative Innovation –
Quieting the Jack Hammer”, Acous. Soc. Amer. 159th Meeting Lay Language Papers,
Popular version of paper 2pNCa9, Presented Tuesday Afternoon, April 20, 2010.
http://www.acoustics.org/press/159th/zwerling.htm viewed 29 April 2011
11. Occupational Safety and Health Administration: Code of Federal Regulations. 29 CFR
1910.95. U. S. Government Printing Office, Office of the Federal Register, OSHA,
Washington DC
12. United States, Public Law 92-574, Oct. 27, 1972, Noise Control Act of 1972, Environmental
Protection Agency, Code of Federal Regulations, 40 CFR Part 211
13. European Union Directive 2000/14/EC of the European Parliament and of the Council,
Official Journal of the European Communities, 7 March 2000, pages L162/32 to L162/36
14. Jacqueline Patel, “Noise emission data for hand-held concrete breakers”, Health and Safety
Executive, RR604 Research Report, Harpur Hill, Buxton, DerbyShire, UK, 12/2007
15. Tony Frazer, Planar Beam Forming Quick Start, Bruel and Kjaer, Canton MI, revision 2.2
September 2010
16. Scarton , H., Diabianca, J.,, Lacey , J., Kennedey, W., 1983. Coulomb Friction Noise and
Vibration Damping, US Patent 4,516,658, filed 28 Feb 1983, and issued 14 May 1985,
17. Hayden CS II, Zechmann E, Hemmelgarn A [2011]. NIOSH Noise Control Activities and
Invitations in Construction. The Center for Construction Research and Training workshop,
Orlando, FL March 2011.
... The 24x24x1.5 inch rubber tiles weighed about 29 lbs each and had a stiffness of 70 Shore A. During testing, the jackhammer operator stood on top of the test stand and chipped through the concrete of the first layer of concrete blocks. The operator was instructed to allow the weight of the jackhammer to do most of the downward work and to apply only downward force on the jackhammer to control the tool [6]. ...
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An effort was made to assess the test method defined in the Noise Emission in the Environment by Equipment for use Outdoors Regulations 2001 (NEEEOR 2001) for usability and repeatability of hand-held concrete breakers. The effort focused on comparing measured noise emission values with manufacturers' declared noise emission values for these devices. It focused on comparing the measured noise emission values with the noise generated by the same tools during simulated real-use tests and establishing whether declared noise emission data was to be used as an indicator of noise hazard. The guaranteed noise emission data declared by the manufacturer and supplied with the concrete breaker was referred to as the declared emission. The noise emission measured by HSL in accordance with the requirements of the NEEEOR 2001 was referred to as the measured emission.
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This is an assessment of occupational noise exposures in the construction industry based on (1) noise measurements observed during Occupational Safety and Health Administration (OSHA) inspections over the period from 1986 through early 1997 and (2) the observed incidence of noise exposures over 85 dB (A) in a national random sample of construction firms done as part of the NIOSH National Occupational Exposure Survey (NOES) in 1981-83. The OSHA inspection data are analyzed by both industry categories and a classification system of equipment and occupational types based on free form descriptions of “job title” by OSHA inspectors. Because construction workers' jobs and work tasks change frequently, the noise observations within each industry were treated as a distribution indicating the fraction of time that workers would be likely to spend at various noise levels projected to a common year (1995). The time at each noise level in OSHA measured dB(A) was summarized in terms of “90 dB(A) equivalents” using the “equal energy rule” which weights a day of exposure time at 100 dB(A), for example, as the equivalent of 10 days of exposure at 90 dB(A). Overall the 1995 projected exposures are slightly less than one “90 dB(A) equivalent” of continuous noise exposure per worker in the industry. This estimate is generally compatible with three other extensive sets of noise measurements for construction workers in the U.S. and Canada. In further work the exposure estimates developed here will be used to project the hearing losses likely to result from work in construction industries. Those results will be compared with extensive available data on the hearing loss experience of construction workers in British Columbia. The results will
Conference Paper
As part of a project to reduce noise induced hearing loss in the construction industry, NIOSH developed a database of sound power level measurements of electric powered hand tools typically used in the construction industry. The tool testing jigs and setups specified and illustrated in ANSI S12.15 were modified to accommodate the higher precision ten-microphone arrangement used in ISO 3744. ANSI S12.15 is sometimes vague regarding the tool testing jig design, so test jigs were designed to supplement existing specifications in the standard. In the course of the project, test jigs were designed, techniques were devised to improve repeatability of measurements, to reduce waste materials, to reduce measurement setup time, and to reduce data acquisition time. Several types of tools were tested including circular saws, grinders, screw drivers, drills, jig saws, reciprocating saws, miter saws, hammer drills, belt sanders, and impact wrenches. The test jig designs and measurement techniques may help others to save time, reduce waste material, and improve measurement repeatability. Additionally, a microphone was placed in the nominal hearing zone of the tool operator to acquire a time series to assess other sound metrics.
Powered Hand Tools Sound Power Level Database
  • C Hayden
  • E Zechmann
  • R Verma
Hayden C., Zechmann E., Verma R., "Powered Hand Tools Sound Power Level Database," Dept. Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, NIOSH, August 2005
Comparison of Sound Power Levels of Portable Powered Hand Tools in the Loaded and Unloaded Condition
  • E Zechmann
  • C S Hayden
Zechmann E, Hayden CS. "Comparison of Sound Power Levels of Portable Powered Hand Tools in the Loaded and Unloaded Condition". INCE Conference Proceedings, Honolulu, HI, December 2006
European Union Directive 2000/14/EC of the European Parliament and of the Council
European Union Directive 2000/14/EC of the European Parliament and of the Council, Official Journal of the European Communities, 7 March 2000, pages L162/32 to L162/36
Planar Beam Forming Quick Start, Bruel and Kjaer, Canton MI, revision 2
  • Tony Frazer
Tony Frazer, Planar Beam Forming Quick Start, Bruel and Kjaer, Canton MI, revision 2.2 September 2010
Coulomb Friction Noise and Vibration Damping, US Patent 4
  • H Scarton
  • J Diabianca
  • J Lacey
  • W Kennedey
Scarton, H., Diabianca, J.,, Lacey, J., Kennedey, W., 1983. Coulomb Friction Noise and Vibration Damping, US Patent 4,516,658, filed 28 Feb 1983, and issued 14 May 1985,