Download NOISE LEVELS OF COMMON CONSTRUCTION POWER TOOLS

NOISE LEVELS OF COMMON CONSTRUCTION POWER TOOLS
By
GREGORY CALLAHAN
A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE IN BUILDING CONSTRUCTION
UNIVERSITY OF FLORIDA
2004
TABLE OF CONTENTS
page
LIST OF TABLES............................................................................................................. iii
LIST OF FIGURES .............................................................................................................v
ABSTRACT...................................................................................................................... vii
CHAPTER
1
INTRODUCTION......................................................................................................1
Hearing Damage in Construction...............................................................................1
Sources of Sound........................................................................................................1
Aims and Objectives ..................................................................................................2
2
LITERATURE REVIEW...........................................................................................4
Properties of Sound ....................................................................................................4
Effects of Sound from More Than One Source..........................................................6
OSHA Regulations.....................................................................................................8
Hearing Damage.......................................................................................................11
3
RESEARCH METHODOLOGY .............................................................................13
Selection of Tools.....................................................................................................13
Measurements...........................................................................................................14
4
RESULTS.................................................................................................................24
5
CONCLUSION ........................................................................................................45
6
RECOMMENDATIONS .........................................................................................48
LIST OF REFERENCES...................................................................................................51
BIOGRAPHICAL SKETCH .............................................................................................52
ii
LIST OF TABLES
Table
page
2-1
Scale for Combining Decibels....................................................................................7
2-2
Change in decibel levels as a function of the distance from the source.....................7
4-1
Porter Cable Circular Saw Center of Room .............................................................29
4-2
Computed Decibel Levels ........................................................................................29
4-3
Black and Decker Circular Saw Center of Room ....................................................30
4-4
Saws All Center of Room.........................................................................................31
4-5
Router Center of Room ............................................................................................31
4-6
Drill Center of Room................................................................................................32
4-7
Two Circular Saws Center of Room ........................................................................32
4-8
Miscellaneous Tools.................................................................................................33
4-9
Beltsander Center of Room ......................................................................................33
4-10 Porter Cable Circular Saw Corner of Room.............................................................34
4-11 Saws All Corner of Room ........................................................................................35
4-12 Router Corner of Room............................................................................................35
4-13 Drill Corner of Room ...............................................................................................35
4-14 Two Circular Saws Corner of Room........................................................................36
4-15 Beltsander Corner of Room......................................................................................36
4-16 Porter Cable Circular Saw Against Wall Indoors ....................................................37
4-17 Drill Against Wall Indoors.......................................................................................38
4-18 Saws All Against Wall Indoors................................................................................38
iii
4-19 Beltsander Against Wall Indoors .............................................................................38
4-20 Router Against Wall Indoors....................................................................................39
4-21 Two Circular Saws Against Wall Indoors................................................................39
4-22 Porter Cable Circular Saw Open Field Measurement ..............................................40
4-23 Black and Decker Circular Saw Open Field Readings ............................................41
4-24 Two Circular Saws Open Field Readings ................................................................41
4-25 Porter Cable Circular Saw Outdoors Corner............................................................42
4-26 Two Circular Saw Outdoor Corner ..........................................................................42
4-27 Porter Cable Circular Saw Outside Against Wall ....................................................43
4-28 Two Circular Saws Outside Against Wall ...............................................................44
iv
LIST OF FIGURES
Figure
page
2-1
Soundwave .................................................................................................................5
3-1
Sound Level Meter ...................................................................................................13
3-2
Inside Center of Room Decibel Level Measurements .............................................16
3-3
Corner of Room Sound Level Measurements ..........................................................17
3-4
Indoor Against Wall Sound Level Measurement .....................................................18
3-5
Open Field Sound Level Measurements ..................................................................20
3-6
Outdoor Corner Sound Level Measurement ............................................................21
3-7
Outdoor Against Wall Sound Level Measurements.................................................22
4-1
Center of Room Noise Levels ..................................................................................25
4-2
Reading Location Differences..................................................................................26
4-3
Porter Cable Circular Saw Measurements ...............................................................27
4-4
Comparison of Two Circular Saws to One Circular Saw ........................................28
v
Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science in Building Construction
NOISE LEVELS OF COMMON CONSTRUCTION POWER TOOLS
By
Gregory Callahan
May, 2004
Chair: Jimmie Hinze
Major Department: Building Construction
The hearing loss of workers in the construction industry is significant. There has
been research performed to measure the noise levels of equipment and tools in the
construction industry, but the results of those studies are vague and unclear. The purpose
of this study is to measure the noise level of numerous common power tools, with the use
of sound level meter, in order to place more definite decibel levels on tools.
The tools measured in the study were portable carpenter hand power tools. The
tools were selected because the tools are present on almost all jobsites, regardless of the
size of the project. These more definite numbers will enable employees in the
construction industry to better guard against hearing loss.
The goal of the study is to better understand the magnitude of the sound levels of
common power tools used in the construction industry. This includes developing an
understanding of the nature of sound as impacted by distance. Also the nature of sounds
in different environments are explored to discover the different sound levels in numerous
situations, to determine which situations place workers at greater risk. The physics of
vii
sound is researched and compared with the results taken to help clarify the data taken in
the study.
viii
CHAPTER 1
INTRODUCTION
Hearing Damage in Construction
The loss of hearing by employees within the construction industry is significant.
Over an extended period of time exposure to loud sounds that are produced on the
construction site can cause hearing damage. It has been a belief within the construction
industry, that construction workers, who are employed for long periods of time, over ten
years, will have hearing loss. The loss of hearing is an enormous problem that many
continue to ignore. “Despite the fact that it is 100 percent preventable, loss of hearing is
one of the most prevalent occupational diseases in the United States and the second
highest self-reported workplace injury or illness.” 1 Hearing loss of workers can have a
drastic negative affect on their lives. Although this problem has been known for a long
time there is little knowledge or research about construction noise that would help to
understand the sounds that cause this prevalent damage.
Sources of Sound
A vast number of power tools are utilized on virtually every construction project,
from the smallest house to the largest skyscraper being constructed. Despite this,
information on the noise levels of common power tools is vague. For instance, OSHA
regulations state that 90 decibels are allowed over an eight hour period of time. But, what
does that mean, or what produces noise levels of 90 decibels? There is generic
information on these types of questions, but no real valuable information. For instance, a
1
http://www.cdc.gov/niosh/pdfs/2001-157.pdf
1
2
circular saw can be said to produce 90 decibels of sound, but what does that mean. Is the
circular saw 90 decibels when cutting wood or just running? Is it at a 90 decibel sound
level to only the operator of the saw? How are other workers in the room affected by the
saw and how close to the saw do they have to be for them to be in danger of hearing
damage? Where is the saw being measured, in the center of a room, corner of room, or an
open field? Does the location of the source make a difference? These questions
demonstrate the complexity of understanding noise. There needs to be a better
understanding of the dynamics of sound in construction in order to effectively reduce the
alarming rate of hearing loss of workers. This misunderstanding of sound is a reason why
there are so few workers that wear hearing protection. Many people in the construction
industry know the noise levels allowed by OSHA, less than 90 decibels over an 8 hour
period, yet these numbers mean nothing to the workers since they do not know what
produces sounds of 90 decibels.
Aims and Objectives
The hearing loss of workers in the construction industry is significant. There has
been research performed to measure the noise levels of equipment and tools in the
construction industry, but the results of those studies are vague and unclear. The purpose
of this study is to measure the noise level of numerous common power tools, with the use
of sound level meter, in order to place more definite decibel levels on tools. The tools
measured in the study were portable carpenter hand power tools. The tools were selected
because the tools are present on almost all jobsite, regardless of the size of the project.
These more definite numbers will enable employees in the construction industry to better
guard against hearing loss. The goal of the study is to better understand the magnitude of
the sound levels of common power tools used in the construction industry. This includes
3
developing an understanding the nature of sound as impacted by distance. Also the nature
of sounds in different environments is explored to discover the different sound levels in
numerous situations, to determine which situations place workers at greater risk. The
physics of sound is researched and compared with the results taken to help clarify the
data taken in the study.
CHAPTER 2
LITERATURE REVIEW
Properties of Sound
Sound is a pressure wave that can be detected by the human ear. The pressure
wave is created by a change in pressure in the atmosphere from some type of vibration or
turbulence. Noise is unwanted sound. “Two basic characteristics of sound waves
important to the subject of noise control are 1. The amplitude, or peak intensity of the
wave 2. The frequency in which the pressure peaks occur. Our sense of hearing can
detect both of these characteristics. Pressure intensity is sensed as loudness. Whereas
pressure is sensed as pitch.” 1The number of cycles that the sound produces in one second
is the frequency of the sound. The frequency is measured in hertz, which is calculated
with the use of a stroboscope. The range of hertz that a human being can detect is
approximately 20 to 20,000 hertz (see figure 2.1). The frequency of a sound is the
detected by human beings as the pitch of that sound. In this study the intensity of sound is
examined, not the pitch.
Intensity of sound, or the strength of the sound, is the wave height that is
produced. The strength of the sound is perceived by human ears as the loudness of sound.
The intensity of sound, the focus of this study, is measured in decibels. Decibels are
measured by the use of sound level meter. The meter measures the sound and expresses
the reading in decibels. Decibels are determined by a logarithmic scale, similar to the
1
pg 209, Asfahal, C. Ray, Industrial Safety and Health Management
4
5
Richter scale in the measurement of earthquakes. The equation that determines the
change in the decibel level is 20 * log (D1/D2). If d1 is greater than d2, the decibel level
will be positive, meaning that the decibel reading is greater at a distance of d2 from the
sound source. This means that a sound with an intensity of 90 decibels has ten times more
power than a sound that has a reading 80 decibels, and when there is a difference of 20
decibels the power is 100 times as strong. A one decibel change would be undetectable to
humans, but a ten decibel difference, although ten times as strong would only be
perceived as twice as loud. The need to use the logarithmic scale is because that the
loudest sound that a human can hear is ten million times greater than the softest sound
detectable to human ears. Therefore to express these readings in more understandable
numbers decibels is used.
Period
( # of hertz)
Wave
Height
(# of
decibels)
Time
Figure 2-1 Soundwave
6
Effects of Sound from More Than One Source
When there is more than one source of sound the decibel level reacts in a certain
manner. For instant if two tools that produce the same decibel level individually are
operating simultaneously, then the decibel level rises in a manner that one may not think.
“If a machine in the plant is very loud, putting a second machine just like it right beside it
will not make the sound twice as loud. Remember that the range of sound pressures is
tremendous and that the human ear hears only a slight increase in loudness, when the
actual sound pressure may have doubled due to the addition of the extra machine. The
decibel scale recognizes the addition of the new machine as an increase in noise level of
only 3 decibels. Conversely, if the noise level in the plant exceeds allowable standards by
very much, shutting off half the machines in the plant – an obviously drastic measure –
may have very little effect in bringing down the total noise level on the decibel scale.
Table 2.1 provides a scale for combining decibels to arrive at a total noise level from two
sources. If there are three or more sources, two sources with the highest decibel levels are
combined and then treated as one source to be combined with a third, and so on, until all
sources have been combined into a single total.”2
The sound pressure level equation enables one to determine the difference in
decibel levels from one distance to another distance. The equation is 20 * Log (Distance
1/ Distance 2). The result of this equation enables one to examine the decrease or increase
as one moves away from or towards a noise source. The distances in the measurements in
this study were plugged into the sound pressure level equation and the estimated decibel
level differences are determined.
2
pg .212, Asfahal, C. Ray, Industrial Safety and Health Management.
7
Table 2-1. Scale for Combining Decibels
Difference between two decibel levels to added
Amount to be added to larger level to obtain
(db)
decibel sum (db)
0
3
1
2.6
2
2.1
3
1.8
4
1.4
5
1.2
6
1
7
0.8
8
0.6
9
0.5
10
0.4
11
0.3
12
0.2
Source: NIOSH (ref Industrial Noise)
A negative decibel change implies as a drop in the decibel reading from d1 to d2.
The exact measurements were not used, but a half a foot either side of the measurement
was used, because the measurements might have not been exact.
Table 2-2. Change in decibel levels as a function of the distance from the source.
d1
1
2
6
20
15
5
d2
2
5
15
8
2
2
0.5
0.4
0.4
2.5
7.5
2.5
-6.02
-7.95
-7.95
7.95
17.50
7.95
d1/d2
decibel drop
8
OSHA Regulations
OSHA regulations state the time limits for certain decibel levels of noise
exposure, and if the sound levels exceed that level then hearing protection should be
provided to the worker. As stated previously these numbers are obtuse and insignificant,
because they do not relate useful information to the construction personnel. For example
if the regulations stated that if a power circular is being used in an enclosed room all
individuals within a 20 foot radius circle should be wearing hearing protection. These
type of prescriptive standard would communicate to workers more understandable
information, instead of just setting regulations on decibel levels. This is the primary
reason why hearing loss is such epidemics within the construction industry, i.e., most of
workers do not know exactly what puts them at risk of damaging their hearing. The
following are the OSHA provisions of the Code of Federal Regulations (CFR) that
pertain to occupational noise exposure and hearing protection.
“ CFR 1926.52(a)
Protection against the effects of noise exposure shall be provided when the sound levels
exceed those shown in Table D-2 of this section when measured on the A-scale of a
standard sound level meter at slow response.
CFR 1926.52(b)
When employees are subjected to sound levels exceeding those listed in Table D-2 of this
section, feasible administrative or engineering controls shall be utilized. If such controls
fail to reduce sound levels within the levels of the table, personal protective equipment as
9
required in Subpart E, shall be provided and used to reduce sound levels within the levels
of the table.
CFR 1926.52(c)
If the variations in noise level involve maxima at intervals of 1 second or less, it is to be
considered continuous.
CFR 1926.52(d)
CFR 1926.52(d)(1)
In all cases where the sound levels exceed the values shown herein, a continuing,
effective hearing conservation program shall be administered.
TABLE D-2 - PERMISSIBLE NOISE EXPOSURES
__________________________________________________
| Sound level
Duration per day, hours | dBA slow
| Response
_________________________________________________
|
8.................................|
90
6.................................|
92
4.................................|
95
3.................................|
97
2.................................|
100
1 1/2...........................|
102
1.................................|
105
1/2..............................|
110
1/4 or less.................. |
115
___________________________________|______________
CFR 1926.52(d)(2)
CFR 1926.52(d)(2)
CFR 1926.52(d)(2)(i)
10
When the daily noise exposure is composed of two or more periods of noise exposure of
different levels, their combined effect should be considered, rather than the individual
effect of each. Exposure to different levels for various periods of time shall be computed
according to the formula set forth in paragraph (d)(2)(ii) of this section.
CFR 1926.52(d)(2)(ii)
F(e)=(T(1)divided by L(1))+(T(2)divided by L(2))+ ... + (T(n) divided by L(n)) where:
F(e) = The equivalent noise exposure factor.
T
= The period of noise exposure at any essentially constant level.
L
= The duration of the permissible noise exposure at the constant level ( Table D- 2).
If the value of F(e) exceeds unity (1) the exposure exceeds permissible levels.
CFR 1926.52(d)(2)(iii)
A sample computation showing an application of the formula in paragraph (d)(2)(ii) of
this section is as follows. An employee is exposed at these levels for these periods:
110 db A 1/4 hour.
100 db A 1/2 hour.
90 db A 1 1/2 hours.
F(e) = (1/4 divided by 1/2)+(1/2 divided by 2)+(1 1/2 divided by 8)
F(e) = 0.500+0.25+0.188
F(e) = 0.938
Since the value of F(e) does not exceed unity, the exposure is within permissible limits.
11
CFR 1926.52(e)
Exposure to impulsive or impact noise should not exceed 140 dB peak sound pressure
level.”(OSHA pg 146)
CFR 1926.101(a)
Wherever it is not feasible to reduce the noise levels or duration of exposures to those
specified in Table D-2, Permissible Noise Exposures, in 1926.52, ear protective devices
shall be provided and used.
CFR 1926.101(b)
Ear protective devices inserted in the ear shall be fitted or determined individually by
competent persons.
CFR 1926.101(c) Plain cotton is not an acceptable protective device.”3
Hearing Damage
Workers exposed to noises in the construction industry are at risk of permanent
hearing loss. The loss of hearing has an extreme negative affect on the lives of workers.
Obviously, the ability to communicate with others becomes difficult. This will put a
strain on everyday activities as well as hobbies such as listening to music. It can also put
the individual in danger of being injured, because of the inability to hear certain sounds.
The loss of hearing also has other health implications such as an increased risk of heart
disease, high blood pressure and strokes.
3
http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10625
12
The origin of hearing loss is the exposure to loud noises. Within the human ear
are fragile hair cells, and when exposed to loud noise over an extended period of time, the
hair cell will become permanently damaged. The small tip of the hair cell, named the
cilia, will be either damaged or break off as the level of the sound increases. These hair
cell do not have the ability to grow back or heal themselves, therefore if damage is done,
it is permanent. Most damage is due to prolonged exposure to loud noises, although
damage can be due through a quick intense noise. Exposure to an 85 or greater decibel
level over an extended period of time will cause permanent hearing loss.4
4
http://www.cdc.gov/niosh/topics/noise/
CHAPTER 3
RESEARCH METHODOLOGY
The measurements in the study performed were done with a sound level meter
from Radio Shack. The Sound Level Meter was set on a weighting of A and at slow
response for all readings. The following is the information on the sound level meter used
in the study from the Radio Shack website (radioshack.com).
Figure 3-1 Sound Level Meter
“The meter precisely measures area noise and other sound levels. You can then use an equalizer to fine-tune your stereo
or home theater system's audio response to match the acoustic environment. The meter's wide-range sound capture
reads from 50 to 126dB SPL in seven ranges with slow or fast response for checking peak and average levels.”1
Selection of Tools
The tools tested in the study included some of the most common portable power
tools that are used on all construction projects. These are the tools selected:
1. Reciprocating Saw (Saws All): Milwaukee 4.0 amps, 120 Volts
1
www.radioshack.com
13
14
2. Router: Black and Decker Deluxe Router 7615
3. Belt Sander: Sears Craftsman Belt Sander Model 315-11721, 120 Volts, 7.0 Amps
4. Circular Saw: Porter Cable 7.25 inch blade, model 347, 120 volt, 15 Amps, 5800 rpm
5. Circular Saw: Black & Decker 7390 7.25 inch blade
6. Drill: Black & Decker, CD 1200, 12 Volt
7. Jig Saw 4935, 120 volts, 3.2 Amps
8. Electric Planer: Hitachi F-20A, 3.4 Amps
9. 9” Sander/Grinder Sears Craftsman 2 HP
10. Ryobi: Detail Carver DC 500
Measurements
The choices of measurements of the sound levels of the different wood working
tools were picked to simulate the different situations in which the tools might be used.
The tools were set in both outside situations and inside situations. All readings are taken
with the tools turned on and not applied to wood, and turned on and applied to wood.
Readings were taken at various distances for each situation, three measurements taken for
each location three times, the three measurements were recorded, and the average reading
was computed and recorded.
Inside Measurements
The measurements were taken in one room with dimensions of 40 feet long by 30
feet wide. The walls of the room were constructed with concrete masonry units. The floor
of the room is made with steel troweled concrete. The ceiling is made of a dropped 10
foot acoustical ceiling. All of the tools were tested in these following situations:
15
In the middle of the room. End tool was placed directly in the middle of the
room, 15 feet from the side walls and 20 feet from the end walls. The tool was set on the
top of a table 30 inches off the floor. In all instances, when measurements were taken,
three separate readings were taken per location. Readings were first taken at 6 inches
from the tool. Readings were then taken 24 inches above the tool, to simulate the decibel
level that the operator of the tool would experience. Then readings were taken at 6 feet
behind, in front, to the left and to the right, of the tool. These readings were taken to
determine the amount of sound level variation at the six foot radius about the tool.
Variations were assumed to be attributed to the room configuration and to the position of
the tool user. The next readings were taken at 15 feet in front (orientation based on the
tool user position) and behind the tool and 13 feet to the left and right of the tool. The
measurements on the side were 13 feet because of the restriction of the room, the
individual holding the sound level meter stood with that individual’s back to the wall, so
the meter was approximately 13 feet from the center of the room. The sound levels of ten
different tools were measured in this setting (see Figure 3.2).
In the corner of the room. In another series of measurements, the tool being
tested was placed directly in the corner of the room 16 inches from the two adjoining
walls. The operator of the tool faced the corner. The tool was set on top of the table 30
inches off the floor. As before, readings were taken at 6 inches from the tool and 24
inches above the tool. Then readings were taken at 6 feet behind the tool ( based on the
operator position), and to the left and to the right of the tool. The next readings were
16
G
C
13’
6’
H
Tool
D
F
J
30’
6’
E
13’
Operator
I
6’
15’
A= location of sound reading 6”
from tool.
B= sound reading taken at 24”
above tool (ear level of operator)
40’
Figure 3-2 Inside Center of Room Decibel Level Measurements
Tools Measured:
1. Reciprocating Saw (Saws All): Milwaukee 4.0 amps, 120 Volts
2. Router: Black and Decker Deluxe Router 7615
3. Belt Sander: Sears Craftsman Belt Sander Model 315-11721, 120 Volts, 7.0 Amps
4. Circular Saw: Porter Cable 7.25 inch blade, model 347, 120 volt, 15 Amps, 5800 rpm
5. Circular Saw: Black & Decker 7390 7.25 inch blade
6. Drill: Black & Decker, CD 1200, 12 Volt
7. Jig Saw 4935, 120 volts, 3.2 Amps
8. Electric Planer: Hitachi F-20A, 3.4 Amps
9. 9” Sander/Grinder Sears Craftsman 2 HP
10. Ryobi: Detail Carver DC 500
taken at 30 feet from the tool directly behind the operator and 15 feet to the left and right
of the tool, along the wall. The sound levels of six different tools were measured in this
setting (see Figure 3.3).
17
Against the wall. A third series of readings were taken with the tool placed
directly in the middle of the 30 foot wall 16 inches from the wall. The operator of the tool
faced the wall. The tool was set on the top of a table 30 inches off the floor. Readings
were taken at 6 inches from the tool and 24 inches above the tool. Then a series of
readings were taken 6 feet from the tool, one behind the operator, one to the left and one
to the right of the operator. The next readings were taken at a distance of 15 feet directly
behind the operator and 13 feet to the left and right of the operator of the tool. The sound
levels of six different tools were measured in this setting (see Figure 3.4).
15’
6’
F
A= location of sound reading 6”
from tool.
B= sound reading taken at 24”
above tool (ear level of operator)
Tool 16” from corner
C
6’
D
(6’ from tool)
E
H
G
Operator
(30’ from tool)
40’
Figure 3-3 Corner of Room Sound Level Measurements
15’
30’
18
Tools Measured:
1. Reciprocating Saw (Saws All): Milwaukee 4.0 amps, 120 Volts
2. Router: Black and Decker Deluxe Router 7615
3. Belt Sander: Sears Craftsman Belt Sander Model 315-11721, 120 Volts, 7.0 Amps
4. Circular Saw: Porter Cable 7.25 inch blade, model 347, 120 volt, 15 Amps, 5800 rpm
5. Circular Saw: Black & Decker 7390 7.25 inch blade
6. Drill: Black & Decker, CD 1200, 12 Volt
F
Operator
C
13’
6’
D
G
30’
(6’ from tool)
(30’ from tool)
6’
E
13’
H
Tool
40’
A= location of sound reading 6”
from tool.
B= sound reading taken at 24”
above tool (ear level of operator)
Figure 3-4 Indoor Against Wall Sound Level Measurement
Tools Measured:
1. Reciprocating Saw (Saws All): Milwaukee 4.0 amps, 120 Volts
2. Router: Black and Decker Deluxe Router 7615
3. Belt Sander: Sears Craftsman Belt Sander Model 315-11721, 120 Volts, 7.0 Amps
4. Circular Saw: Porter Cable 7.25 inch blade, model 347, 120 volt, 15 Amps, 5800 rpm
5. Circular Saw: Black & Decker 7390 7.25 inch blade
6. Drill: Black & Decker, CD 1200, 12 Volt
19
Outdoor Measurements
Measurements were taken outdoors to compare the sound measurements with the
indoor conditions of the 30’ by 40’ room. Therefore the measurements taken outside were
otherwise intended to be similar to the indoor measurement situations.
Measurements in the open outdoors. The tool was tested 91 feet from the
nearest building, with the operator of the tool facing away from the building. The
measurements taken were similar to the readings taken for the middle of the room
conditions. The tool was set on the top of a table 30 inches off the ground, which was
grass and dirt. Readings are taken at 6 inches from the tool and 24 inches above the tool.
Then readings are then taken 6 feet from the tool: behind, in front, to the left and to the
right of the operator. Readings were then taken at 15 feet from the tool in front of the
operator, behind the operator, and 15 feet to the left and right of the operator. Three tools
were measured in this condition, namely the two circular saws: Porter Cable 7.25 inch
blade model 347, and the Black & Decker 7390 7.25 inch blade. Measurements were also
taken with both circular saws simulataneousley operating (see Figure 3.5).
20
G
A= location of sound reading 6”
from tool.
B= sound reading taken at 24”
above tool (ear level of operator)
C
15’
6’
H
Tool
D
F
J
6’
Nearest
Building 81’
feet from
Building
E
Operator
15’
I
6’
15’
6’
15’
Figure 3-5 Open Field Sound Level Measurements
In corner outdoors. Similar to the testing done inside the room the tool was
tested in an outdoors corner. The tools being measured were placed in a 90 degree corner
of a 8 foot high brick wall. The walking surface was rough finished concrete. The tool
being tested was placed directly in the corner of the wall 16 inches from the two
adjoining walls. The operator of the tool faced the corner. The tool was set on the top of a
table 30 inches off the ground. Readings are taken at 6 inches from the tool and 24 inches
above the tool. Then readings were taken at 6 feet from the tool: behind, to the left and to
the right of the operator. The next readings were taken at 15 feet from the tool: behind the
operator and 15 feet to the left and to the right of the operator. Two tools were measured
in this setting, a circular saw: Porter Cable 7.25 inch blade model 347, and two circular
saws simulataneousley operating (see Figure 3.6).
21
Building
Tool
F
A= location of sound reading 6”
from tool.
B= sound reading taken at 24”
above tool (ear level of operator)
C
6’
D
E
Operator
15’
G
(15’ from tool)
H
8’ High Brick Wall
15’
6’
Figure 3-6 Outdoor Corner Sound Level Measurement
Against the wall outdoors. Sound measurements were taken against a 38 foot
outdoor wall. The wall was constructed of insulated metal panels. Sound measurements
taken were similar to the readings taken against the wall inside the room, for the purpose
of making comparisons. The operator of the tool faced the wall. The tool was set on the
top of a table 30 inches off the rough finished concrete ground. Readings were taken at 6
inches from the tool and 24 inches above the tool. Then readings are taken at 6 feet from
the tool behind, to the left and to the right, of the operator. The next readings were taken
at 15 feet from the tool behind the operator and 15 feet to the left and right of the
operator. In this setting two tools were measured for sound levels produced, a circular
saw: Porter Cable 7.25 inch blade model 347, and two circular saws simulataneousley
operating (see Figure 3.7).
22
A = lo c a tio n o f s o u n d r e a d in g 6 ”
fro m to o l.
B = s o u n d r e a d in g ta k e n a t 2 4 ”
a b o v e to o l (e a r le v e l o f o p e ra to r)
Tool
H
15’
E
6’
G
D
(6 ’ fro m to o l)
6’
(3 0 ’ fro m to o l)
C
15’
O p e ra to r
F
B u ild in g
Figure 3-7 Outdoor Against Wall Sound Level Measurements
Two Tool Measurements
Measurements taken with two tools turned on at the same time. Because of safety
concerns, no measurements were taken with two tools cutting wood at the same time; all
measurements were taken with the tools freewheeling. The two tools used in the two tool
readings were the Circular Saw: Porter Cable 7.25 inch blade, model 347, 120 volt, 15
Amps, 5800 rpm, and the Circular Saw: Black & Decker 7390 7.25 inch blade. There was
one operator for both tools. The operator had one saw in each hand in the prescribed
positions as described previously. All the situations described earlier (indoor and
23
outdoor) were repeated for the two tool readings. The tools were measured for sound
levels in all settings previously described.
CHAPTER 4
RESULTS
The results are calculated by measuring the sound level three times for each
measurement. The average of the three readings was then calculated and recorded in
tables. For each measurement location a letter was assigned. The letters in the table
depict the placement of the sound level meter in relation to the tool, and correspond to the
sound measurement location shown in Figures 3.2 to 3.7. When a letter in the tables is
followed by an apostrophe (’) this indicate that this measurement was taken while the tool
was cutting wood. No mark next to the letter means that the tool was measured while not
cutting wood.
Center of room noise levels. Five tools were evaluated in the center of the room
condition. To illustrate the drop in decibels with the distance from the tool, a simple
figure was created. Figure 4.1 shows the sound level measurements at location A (6
inches from the tool), B (24 inches above the tool), F (6 feet in front of the tool), G (15
feet in front of the tool). All measurements shown in Figure 4.1 were taken while the
tools were not cutting wood. (refer back to Figure 3.2). In addition, an arbitrary value of
95 decibels was assigned as a fictional sound level reading at position A. Computations
were made to determine the decline in decibels as a function of the distance from the tool.
The computations show that the sound level would decline 29.7 decibels from the
location of the tool to a position of 15 feet from the tool (computed value is the dark line
in Figure 4.1)
24
25
Sound Measurements of the six tools declined with distance from the tool, but the
decline was not as extreme as the computed number. The decibel drop for the tools that
were measured ranged from 17.3 to 18.3 decibels. Thus, it is apparent that the sound level
decline, which was consistent among the tools, was considerably less than would be
predicted by the formula alone.
Sound measurements were taken with the additional four tools but only at the 6
inch and 24 inch locations.
110
100
Assigned value
Decibel
90
Computed
PC circular saw
Saws All
Router
Drill
Beltsander
BD circular saw
80
70
60
50
A =.5 ft.
B=2 ft
C=6 ft
G=15 ft
Distance
Figure 4-1 Center of Room Noise Levels
Body position. The results clearly show that the position of the operator
significantly affect the decibel level of sound emitted by tools. The data from the tables
consistently demonstrate that readings taken somewhat behind the tool operator
(positions D, E, H, and I) had lower sound levels than the other measurements. As shown
26
in Figure 3.2 to 3.7 the body of the operator is in the path of the sound in the
measurements D, E, H, and I. This characteristic can also be seen from Figure 4.2. This
graph demonstrates the results of the six feet measurements of the Porter Cable Circular
Saw in all settings, while cutting wood. Clearly the 6’ back and the 6’ left measurements
are lower than the other measurements, with few exceptions.
110
108
106
104
102
100
Decibel
98
96
6' front
6' back
6' Left
6' right
94
92
90
88
86
84
82
80
78
Center of Room Indoor against
Wall
Indoor Corner
Open Area
Outdoor
Outdoor Against Outdoor Corner
wall
Measurement Situation
Figure 4-2 Reading Location Differences
Porter cable circular saw in all measurement settings. In Figure 4.3 the Porter
Cable circular Saw is shown in all settings, measured at 24 inches from the tool, while
cutting wood and not cutting wood. The graph shows how one tool had drastically
different sound levels, depending on the environment in which it was measured and
depending whether or not it was cutting wood. The tool had the highest sound levels in
the corner of the room. This high reading is because of the reflection of sound from the
27
walls. The lack of reflection of sound was the reason the lowest reading was from the
outdoor open area reading. This demonstrates that the environment that a tool is
measured will affect the sound level drastically.
110
105
Decibel
100
Not Cutting at 24"
Cutting 24"
95
90
85
Center of
Room
Indoor Against Indoor against
Wall
Corner
Open Area
Outdoor
Outdoor
Against wall
Outdoor
Corner
Reading Situation
Figure 4-3 Porter Cable Circular Saw Measurements
Comparison of two circular saws to one circular saw in all measurement
situations. Figure 4.4 displays the sound levels of two circular simultaneously running
without cutting wood, the sound level of one circular saw running without cutting wood,
and the computed sound levels of the two saws determined from Table 2.1. The sound
levels shown are for all situations with the sound level meter at 24 inches from the tool.
The graph shows that the computed value for the sound level of two tools is not accurate
in comparison to the actual readings taken. Again this demonstrates that the computed
values of sound levels are not accurate, because of the various environments in which the
sound levels can be measured.
28
103
101
99
Decibel
97
Porter Cable Saw at 24"
2 Circular Saws
95
Computed
93
91
89
87
Center of Room
Indoor against
Wall
Indoor Corner
Open Area
Outdoor
Outdoor Against
wall
Outdoor Corner
Measurement Situation
Figure 4-4 Comparison of Two Circular Saws to One Circular Saw
Center of room results. The Porter Cable circular saw sound level results for the
middle of the room were recorded in Table 4.1. The various measurement locations were
shown on the left hand column. The locations of the measurements as are illustrated in
Figure 3.2. Three different readings were taken for each measurement location and are
shown in Table 4.1 as Reading 1, Reading 2 and Reading 3. The average of these
readings was calculated and recorded under the Average column heading. In the far right
hand column is the computed decibel value. The A and A’ in the computed column were
assigned values, therefore the average of the actual readings in those locations was used.
The remaining computed values were calculated by using the sound pressure level
equation, 20 * Log (Distance 1/ Distance 2). Table 4.2 illustrates the calculated decibel
drop using the sound pressure level equation. The calculated values were subtracted from
29
both the A and A’ values, to determine the predicted sound level at different distances.
These calculations were recorded in the computed column of Table 4.1, and are shown to
illustrate the differences in the actual sound level readings and the computed sound levels.
Table 4-1. Porter Cable Circular Saw Center of Room
Circular Saw: Center of Room
Location A
A'
B
B'
C
C'
D
D'
E
E'
F
F'
G
G'
H
H'
I
I'
J
J'
Reading
1
100
115
92
108
90
96
85
94
81
95
88
98
84
91
80
95
81
95
83
92
Reading
2
101
115
93
109
89
95
84
95
81
96
89
98
83
92
80
94
81
95
84
92
Reading
3
102
114
93
108
90
95
85
96
81
97
88
98
84
91
81
95
81
95
84
92
Average
101.0
114.7
92.7
108.3
89.7
95.3
84.7
95.0
81.0
96.0
88.3
98.0
83.7
91.3
80.3
94.7
81.0
95.0
83.7
92.0
Computed
101
114.7
88.96
102.66
79.42
93.12
79.42
93.12
79.42
93.12
79.42
93.12
71.5
85.2
71.5
85.2
71.5
85.2
71.5
85.2
Table 4-2. Computed Decibel Levels
Computed No Range
d1
d2
d1/d2
decibel drop
0.5
2
0.25
-12.0412
0.5
6
0.083333
21.58362
0.5
15
0.0333333
-29.54243
Tables 4.3 to Table 4.9 represent the remaining tools that were measured for
sound levels in the center of the room. The tables were recorded in the same manner as
Table 4.1, except that the computed decibel value was not calculated in Tables 4.3 to 4.9.
The tools in order of the tables are.
30
Table 4.3 Circular Saw: Black & Decker 7390 7.25 inch blade
Table 4.4 Reciprocating Saw (Saws All): Milwaukee 4.0 amps, 120 Volts
Table 4.5 Router: Black and Decker Deluxe Router 7615
Table 4.6. Drill: Black & Decker, CD 1200, 12 Volt
Table 4.7 Two Circular Saw: Porter Cable 7.25 inch blade, model 347, 120 volt, 15
Amps, 5800 rpm and Circular Saw: Black & Decker 7390 7.25 inch blade
Table 4.8 Miscelleneous Tools: Jig Saw 4935, 120 volts, 3.2 Amps,
Electric Planer: Hitachi F-20A, 3.4 Amps
9” Sander/Grinder Sears Craftsman 2 HP
Ryobi: Detail Carver DC 500
Table 4.9 Belt Sander: Sears Craftsman Belt Sander Model 315-11721, 120 Volts, 7.0
Amps.
Table 4-3. Black and Decker Circular Saw Center of Room
Circular Saw: Center of
Room
Location A
A'
B
B'
C
C'
D
D'
E
E'
F
F'
G
G'
H
H'
I
I'
J
J'
Reading
1
101
115
92
109
91
97
85
95
82
96
90
99
84
92
81
97
82
95
85
93
Reading
2
102
116
94
109
90
95
86
97
80
96
91
98
85
93
81
96
82
96
84
93
Reading
3
102
114
94
108
90
96
86
96
83
98
92
99
83
91
81
95
81
95
85
92
Average
101.7
115.0
93.3
108.7
90.3
96.0
85.7
96.0
81.7
96.7
91.0
98.7
84.0
92.0
81.0
96.0
81.7
95.3
84.7
92.7
31
Table 4-4. Saws All Center of Room
Saws All: Center of Room
Location A
A'
B
B'
C
C'
D
D'
E
E'
F
F'
G
G'
H
H'
I
I'
J
J'
Reading 1
98
101
89
92
85
87
85
81
86
86
85
88
80
78
78
76
78
80
79
82
Reading 2
98
101
88
91
84
88
86
81
85
86
85
89
79
79
79
77
79
79
80
82
Reading 3
98
101
89
91
86
87
85
82
85
87
85
88
80
79
78
76
78
79
80
82
Table 4-5. Router Center of Room
Router: Center of Room
Location A
A'
B
B'
C
C'
D
D'
E
E'
F
F'
G
G'
H
H'
I
I'
J
J'
Reading 1
102
102
99
100
89
100
91
93
88
90
90
94
84
87
84
87
85
87
88
88
Reading 2
103
101
98
101
89
101
92
94
88
91
91
95
85
88
84
88
86
87
89
89
Reading 3
103
101
99
101
90
101
92
93
88
90
90
95
85
88
84
88
85
87
88
89
Average
102.7
101.3
98.7
100.7
89.3
100.7
91.7
93.3
88.0
90.3
90.3
94.7
84.7
87.7
84.0
87.7
85.3
87.0
88.3
88.7
Average
98.0
101.0
88.7
91.3
85.0
87.3
85.3
81.3
85.3
86.3
85.0
88.3
79.7
78.7
78.3
76.3
78.3
79.3
79.7
82.0
32
Table 4-6. Drill Center of Room
Drill: Center of Room
Location A
A'
B
B'
C
C'
D
D'
E
E'
F
F'
G
G'
H
H'
I
I'
J
J'
Reading 1
76
83
71
79
64
70
66
70
64
68
68
71
60
63
59
62
60
60
59
61
Reading 2
77
83
72
78
65
71
66
71
64
68
68
71
59
62
60
61
59
61
59
61
Reading 3
77
83
72
79
64
70
66
72
64
69
69
71
59
63
59
62
59
61
60
61
Average
76.7
83.0
71.7
78.7
64.3
70.3
66.0
71.0
64.0
68.3
68.3
71.0
59.3
62.7
59.3
61.7
59.3
60.7
59.3
61.0
Table 4-7. Two Circular Saws Center of Room
Both Circular Saws Center of Room
Location A
B
C
D
E
F
G
H
J
Reading 1
110
96
92
88
99
88
84
90
89
Reading 2
111
97
93
89
99
89
85
91
90
Reading 3
109
96
91
88
97
89
86
92
89
In Table 4.8 only the 6 inch and the 24 inch sound level readings were recorded.
Only these readings were used because these tools are not as common on construction
jobsites as the other tools recorded.
Indoor corner of room readings. The results of the sound level readings from
the tools operated in the corner of the 30 feet by the 40 feet room are recorded in Tables
Average
110.0
96.3
92.0
88.3
98.3
88.7
85.0
91.0
89.3
33
4.10 to 4.15. The different measurement locations are displayed in the left hand column.
The locations of the measurements are as were described in Figure 3.3. Three various
Table 4-8. Miscellaneous Tools
Miscellaneous Tools
Jigsaw Location A
Jigsaw Location B
Planer Location A
Planer Location B
Grinder Location A
Grinder Location B
Carver Location A
Carver Location B
Reading 1
111
99
118
96
118
108
82
72
Reading 2
112
100
118
96
118
107
84
72
Reading 3
113
99
117
99
121
107
89
77
Average
112.0
99.3
117.7
97.0
119.0
107.3
85.0
73.7
Table 4-9. Beltsander Center of Room
Beltsander: Center of
Room
Location A
A'
B
B'
C
C'
D
D'
E
E'
F
F'
G
G'
H
H'
I
I'
J
J'
Reading 1
108
111
103
97
93
94
93
94
95
92
97
92
88
85
88
85
91
88
91
90
Reading 2
109
111
102
97
93
93
94
95
96
93
98
92
87
86
88
84
91
88
91
89
Reading 3
108
112
104
98
93
92
93
95
96
92
97
93
88
86
88
86
92
89
90
90
Average
108.3
111.3
103.0
97.3
93.0
93.0
93.3
94.7
95.7
92.3
97.3
92.3
87.7
85.7
88.0
85.0
91.3
88.3
90.7
89.7
readings are taken for each measurement location and are shown as Reading 1, Reading 2
and Reading 3. The average of these readings was calculated and recorded under the
Average column heading on the right side of the tables. The tools measured are listed in
order in the following tables;
34
Table 4.10 Circular Saw: Porter Cable 7.25 inch blade, model 347, 120 volt, 15 Amps,
5800 rpm
Table 4.11 Reciprocating Saw (Saws All): Milwaukee 4.0 amps, 120 Volts
Table 4.12 Router: Black and Decker Deluxe Router 7615
Table 4.13 Drill: Black & Decker, CD 1200, 12 Volt
Table 4.14 Two Circular Saws. Black & Decker 7390 7.25 inch blade, and the Porter
Cable 7.25 inch blade, model 347, 120 volt, 15 Amps, 5800 rpm
Table 4.15. Belt Sander: Sears Craftsman Belt Sander Model 315-11721, 120 Volts, 7.0
Amps.
Table 4-10. Porter Cable Circular Saw Corner of Room
Circular Saw Corner of
Room
Location A
A'
B
B'
C
C'
D
D'
E
E'
F
F'
G
G'
H
H'
Reading 1
103
113
99
109
92
101
88
103
91
98
80
93
79
89
81
89
Reading
2
103
114
99
108
92
100
88
104
90
99
80
93
79
88
81
90
Reading 3
104
114
100
109
91
101
87
103
91
98
80
92
80
89
81
90
Average
103.3
113.7
99.3
108.7
91.7
100.7
87.7
103.3
90.7
98.3
80.0
92.7
79.3
88.7
81.0
89.7
Indoor Against Wall Sound Level Measurements. The results of the sound
level readings from the tools placed indoors against a 30 foot wall were recorded in
Tables 4.16 to 4.21. The different measurement locations were displayed under the
column furthest to left in each table. The locations of the measurements are as described
35
Table 4-11. Saws All Corner of Room
Saws All: Corner of
Room
Location A
A'
B
B'
C
C'
D
D'
E
E'
F
F'
G
G'
H
H'
Reading 1
94
92
88
87
79
81
77
79
80
80
75
75
69
70
71
72
Reading 2
93
93
89
87
80
81
77
80
80
81
76
74
69
71
71
71
Reading 3
96
93
88
88
79
80
78
80
80
81
76
74
70
70
71
72
Average
94.3
92.7
88.3
87.3
79.3
80.7
77.3
79.7
80.0
80.7
75.7
74.3
69.3
70.3
71.0
71.7
Table 4-12. Router Corner of Room
Router: Corner of
Room
Location A
A'
B
B'
C
C'
D
D'
E
E'
F
F'
G
G'
H
H'
Reading 1
101
102
92
94
88
90
84
88
84
91
80
77
74
75
75
77
Reading 2
102
102
93
95
88
92
85
88
84
91
84
78
75
74
75
78
Reading 3
100
100
94
94
89
90
85
88
84
92
80
78
75
75
74
77
Average
101.0
101.3
93.0
94.3
88.3
90.7
84.7
88.0
84.0
91.3
81.3
77.7
74.7
74.7
74.7
77.3
Table 4-13. Drill Corner of Room
Drill: Corner of Room
Location A
A'
B
B'
C
C'
Reading 1
73
75
66
70
62
62
Reading 2
73
75
66
72
62
63
Reading 3
72
76
65
71
63
64
Average
72.7
75.3
65.7
71.0
62.3
63.0
36
Table 4-13 Continued
Drill: Corner of Room
D
D'
E
E'
F
F'
G
G'
H
H'
Reading 1
60
61
61
61
50
54
54
54
60
53
Reading 2
59
62
62
60
52
55
55
55
59
53
Reading 3
60
60
60
62
50
54
54
54
60
53
Average
59.7
61.0
61.0
61.0
50.7
54.3
54.3
54.3
59.7
53.0
Table 4-14. Two Circular Saws Corner of Room
2 Circular Saws Corner
Room
Location A
B
C
D
E
F
G
H
Reading 1
109
100
97
99
95
88
87
87
Reading 2
110
101
98
100
96
88
88
88
Reading 3
108
100
99
98
95
88
87
87
Average
109.0
100.3
98.0
99.0
95.3
88.0
87.3
87.3
Table 4-15. Beltsander Corner of Room
Beltsander: Corner of
Room
Location A
A'
B
B'
C
C'
D
D'
E
E'
F
F'
G
G'
H
H'
Reading 1
109
101
98
89
89
84
85
83
88
85
79
79
78
74
78
77
Reading 2
110
101
99
90
89
84
85
84
88
85
78
78
77
75
78
77
Reading 3
108
102
99
89
90
85
86
84
89
86
79
79
77
74
79
78
Average
109.0
101.3
98.7
89.3
89.3
84.3
85.3
83.7
88.3
85.3
78.7
78.7
77.3
74.3
78.3
77.3
37
in Figure 3.4. Three separate readings were taken for each measurement location and are
shown as Reading 1, Reading 2 and Reading 3. The average of these readings were
calculated and recorded under the average column heading on the far right side of the
tables. The following tools are listed in the tables;
Table 4.16 Circular Saw: Porter Cable 7.25 inch blade, model 347, 120 volt, 15 Amps,
5800 rpm
Table 4.17 Black & Decker, CD 1200, 12 Volt
Table 4.18 Reciprocating Saw (Saws All): Milwaukee 4.0 amps, 120 Volts
Table 4.19. Belt Sander: Sears Craftsman Belt Sander Model 315-11721, 120 Volts, 7.0
Amps.
Table 4.20 Router: Black and Decker Deluxe Router 7615
Table 4.21 Two Circular Saws. Black & Decker 7390 7.25 inch blade, and the Porter
Cable 7.25 inch blade, model 347, 120 volt, 15 Amps, 5800 rpm
Table 4-16. Porter Cable Circular Saw Against Wall Indoors
Circular Saw: Middle of Wall
Location A
A'
B
B'
C
C'
D
D'
E
E'
F
F'
G
G'
H
H'
Reading 1
101
113
95
107
89
91
97
96
91
100
83
93
79
89
81
95
Reading 2
101
114
94
108
90
91
97
95
91
100
82
92
80
90
82
94
Reading 3
101
115
95
108
89
92
98
96
92
100
83
93
79
89
81
95
Average
101.0
114.0
94.7
107.7
89.3
91.3
97.3
95.7
91.3
100.0
82.7
92.7
79.3
89.3
81.3
94.7
38
Table 4-17. Drill Against Wall Indoors
Drill: Middle of Wall
Location A
A'
B
B'
C
C'
D
D'
E
E'
F
F'
G
G'
H
H'
Reading 1
80
84
72
76
62
70
58
68
65
70
56
64
56
57
59
68
Reading 2
79
84
73
77
61
70
58
67
65
69
56
64
55
57
60
66
Reading 3
80
85
72
76
62
69
59
68
65
71
56
64
56
58
59
66
Average
79.7
84.3
72.3
76.3
61.7
69.7
58.3
67.7
65.0
70.0
56.0
64.0
55.7
57.3
59.3
66.7
Table 4-18. Saws All Against Wall Indoors
Saws All: Middle of Wall
Location A
A'
B
B'
C
C'
D
D'
E
E'
F
F'
G
G'
H
H'
Reading 1
98
93
90
89
79
83
82
83
84
85
74
80
73
75
81
83
Reading 2
98
94
90
90
79
82
83
83
84
86
74
80
74
76
81
84
Reading 3
99
94
89
90
79
82
83
83
84
85
75
81
73
75
80
83
Average
98.3
93.7
89.7
89.7
79.0
82.3
82.7
83.0
84.0
85.3
74.3
80.3
73.3
75.3
80.7
83.3
Table 4-19. Beltsander Against Wall Indoors
Beltsander: Middle of Wall
Location A
A'
B
B'
C
C'
D
D'
Reading 1
115
109
102
103
93
91
92
95
Reading 2
114
110
103
103
93
91
92
95
Reading 3
115
110
103
104
94
92
92
94
Average
114.7
109.7
102.7
103.3
93.3
91.3
92.0
94.7
39
Table 4-19 Continued
Beltsander: Middle of Wall
E
E'
F
F'
G
G'
H
H'
Reading 1
97
95
87
87
85
85
93
92
Reading 2
98
95
87
88
86
85
94
92
Reading 3
99
95
88
87
85
86
93
92
Average
98.0
95.0
87.3
87.3
85.3
85.3
93.3
92.0
Reading 2
104
106
99
102
88
93
92
93
93
90
81
86
78
83
89
88
Reading 3
105
105
99
101
88
93
93
93
92
91
81
87
79
84
90
88
Average
104.3
105.7
98.7
101.7
88.3
93.3
92.3
92.7
92.7
90.3
81.3
86.3
78.3
83.3
89.3
87.7
Table 4-20. Router Against Wall Indoors
Router: Middle of Wall
Location A
A'
B
B'
C
C'
D
D'
E
E'
F
F'
G
G'
H
H'
Reading 1
104
106
98
102
89
94
92
92
93
90
82
86
78
83
89
87
Table 4-21. Two Circular Saws Against Wall Indoors
2 Circular Saws Middle of Wall
Inside
Location A
B
C
D
E
F
G
H
Reading 1
110
98
94
90
98
87
88
90
Reading 2
112
98
95
91
97
89
89
89
Reading 3
112
99
96
90
99
88
90
89
Average
111.3
98.3
95.0
90.3
98.0
88.0
89.0
89.3
Open field sound level measurements. The results of the sound level
measurements in an open field are displayed in Tables 4.22 to 4.24. The measurement
40
locations are shown on the far left column of the table. All the measurement locations are
in accordance with the measurement locations noted in Figure 3.5. Three separate
readings are taken for each measurement location and are shown as Reading 1, Reading 2
and Reading 3. The average of the three readings taken at each location were calculated
and recorded under the average column heading of the tables. The decibels of these
readings are substantially lower than the decibel levels of the indoor readings, as was
displayed in Figure 4.3. The tables and the tools are shown in the following order;
Table 4.22 Circular Saw: Porter Cable 7.25 inch blade, model 347, 120 volt, 15 Amps,
5800 rpm
Table 4.23 Circular Saw: Black & Decker 7390 7.25 inch blade
Table 4.21 Two Circular Saws. Black & Decker 7390 7.25 inch blade, and the Porter
Cable 7.25 inch blade, model 347, 120 volt, 15 Amps, 5800 rpm.
Table 4-22. Porter Cable Circular Saw Open Field Measurement
Circular Saw: Outside
Location A
A'
B
B'
C
C'
D
D'
E
E'
F
F'
G
G'
H
H'
I
I'
J
J'
Reading 1
99
112
88
100
82
87
73
91
79
92
80
90
73
81
68
80
72
90
72
81
Reading 2
98
113
88
99
82
88
74
92
80
93
81
90
73
82
67
81
72
89
72
82
Reading 3
100
112
89
100
81
88
73
91
80
93
81
89
72
82
67
80
73
89
73
82
Average
99.0
112.3
88.3
99.7
81.7
87.7
73.3
91.3
79.7
92.7
80.7
89.7
72.7
81.7
67.3
80.3
72.3
89.3
72.3
81.7
41
Table 4-23. Black and Decker Circular Saw Open Field Readings
B&D Circular Saw :
Outside
Reading 1
Reading 2
Reading 3
Location A
A'
B
B'
C
C'
D
D'
E
E'
F
F'
G
G'
H
H'
I
I'
J
J'
100
110
87
102
84
91
77
82
87
95
88
90
75
83
67
81
74
93
75
83
101
109
86
103
84
92
77
83
87
95
89
91
76
84
66
82
74
94
75
83
Average
101
110
87
102
83
91
76
83
86
96
88
90
77
83
67
81
75
94
74
84
100.7
109.7
86.7
102.3
83.7
91.3
76.7
82.7
86.7
95.3
88.3
90.3
76.0
83.3
66.7
81.3
74.3
93.7
74.7
83.3
Table 4-24. Two Circular Saws Open Field Readings
2 Circular Saws : Outside
Location A
B
C
D
E
F
G
H
I
J
Reading 1
98
88
82
81
88
87
77
76
77
77
Reading 2
99
88
83
80
88
87
77
76
77
77
Reading 3
99
89
82
81
89
88
76
75
78
76
Average
98.7
88.3
82.3
80.7
88.3
87.3
76.7
75.7
77.3
76.7
Outdoor corner sound level measurements. The results of the sound level
measurements in an outdoor corner are shown in Tables 4.25 and 4.26. The measurement
locations are visible on the far left column of the table and correspond with the
measurement locations shown in Figure 3.6. The average of these readings were
calculated and recorded under the Average column heading of the tables. The decibels of
these readings are substantially higher than the decibel levels of the other outdoor
42
measurements, similar to the indoor corner measurements. The configuration of a corner
results in a lower reduction of the decibel level of a sound, which was displayed in Figure
4.3. The Tables and the tools that the tables represent are in the following order
Table 4.25 Circular Saw: Porter Cable 7.25 inch blade, model 347, 120 volt, 15 Amps,
5800 rpm
Table 4.26 Two Circular Saws. Black & Decker 7390 7.25 inch blade, and the Porter
Cable 7.25 inch blade, model 347, 120 volt, 15 Amps, 5800 rpm.
Table 4-25. Porter Cable Circular Saw Outdoors Corner
PC Circular Saw Corner
Outdoors
Location A
A'
B
B'
C
C'
D
D'
E
E'
F
F'
G
G'
H
H'
Reading 1
102
126
98
108
91
104
87
103
91
108
84
96
82
99
81
97
Reading 2
103
125
99
109
92
104
88
104
90
109
84
96
81
98
82
98
Reading 3
102
123
98
110
92
103
87
103
91
107
85
97
82
98
82
98
Table 4-26. Two Circular Saw Outdoor Corner
2 Circular Saws Corner
Outside
Location A
B
C
D
E
F
G
H
Reading 1
109
103
99
93
99
89
88
87
Reading 2
110
102
99
94
100
89
87
88
Reading 3
109
103
98
94
99
89
87
87
Average
109.3
102.7
98.7
93.7
99.3
89.0
87.3
87.3
Average
102.3
124.7
98.3
109.0
91.7
103.7
87.3
103.3
90.7
108.0
84.3
96.3
81.7
98.3
81.7
97.7
43
Outside against wall sound level measurements. The results of the sound level
measurements of the tools tested on a wall outdoors are displayed in Tables 4.27 and
4.28. The measurement locations are shown in on the left column of the table. All the
measurement locations correspond with the measurement locations shown in Figure 3.7.
The average of these readings were calculated and recorded under the average column
heading of the tables. The tools represented in the tables are shown in the following
order;
Table 4.27 Circular Saw: Porter Cable 7.25 inch blade, model 347, 120 volt, 15 Amps,
5800 rpm
Table 4.28 Two Circular Saws. Black & Decker 7390 7.25 inch blade, and the Porter
Cable 7.25 inch blade, model 347, 120 volt, 15 Amps, 5800 rpm.
Table 4-27. Porter Cable Circular Saw Outside Against Wall
Circular Saw: Middle of Wall Outside
Location A
A'
B
B'
C
C'
D
D'
E
E'
F
F'
G
G'
H
H'
Reading 1
101
119
89
106
74
98
74
97
82
108
75
90
69
94
75
98
Reading
2
102
120
89
107
75
98
75
97
81
108
75
89
68
93
75
99
Reading 3
100
119
88
107
74
97
74
98
81
109
75
90
69
93
76
99
Average
101.0
119.3
88.7
106.7
74.3
97.7
74.3
97.3
81.3
108.3
75.0
89.7
68.7
93.3
75.3
98.7
44
Table 4-28. Two Circular Saws Outside Against Wall
2 Saws: Middle of Wall
Outside
Location A
B
C
D
E
F
G
H
Reading 1
109
100
94
88
94
87
81
88
Reading 2
110
101
94
88
96
87
80
88
Reading 3
110
101
95
89
95
86
81
87
Average
109.7
100.7
94.3
88.3
95.0
86.7
80.7
87.7
CHAPTER 5
CONCLUSION
The sound level measurements taken in this study are not consistent with the
theoretical levels that were determined through the sound pressure level equation 20 * log
(D1/D2). When the actual measured data are compared to the theoretical data, the
numbers are extremely fairly close, in all measurements both indoors and outdoors. This
is extremely important, because it verifies the fact that the equation is not a reliable
reference to measure the decibel levels in a work area.
The sound level equation is a function of distance. The environment in which
sounds are created is not taken into account when the formula is calculated. The results
from Figure 4.3 clearly illustrate that the environment in which a sound is produced has a
drastic effect on the decibel level. This is clearly illustrated in Figure 4.3. The chart
displays the Porter Cable circular saw in all environmental settings. The displayed
readings are the 24 inch readings while cutting wood and not cutting wood. If the
environment was not a factor of the sound levels then the sound levels for the settings
should be the same, but that is not the case. The indoor corner reading has the highest
decibel level, 109 decibels. This is because when tool is operated in a corner the sound is
reflected. The material of the room also helped to magnify the reflection of sound. The
walls were constructed out of concrete masonry units and the floor was concrete. The
open field results in were the lowest sound level in Figure 4.3 by a large amount. The
ground in this setting was grass, and there were no buildings near to reflect the sound.
45
46
The decibel difference from the saw cutting wood in a corner to the saw not cutting wood
in an outdoor open area is 21 decibels. This means that the same tool in one setting
produces a sound over 100 times as powerful as the same tool in another setting. The
OSHA standards would also be easily violated in one setting and within the OSHA rules
in another setting. This obviously demonstrates that when a tool is given a decibel value,
such as a circular saw is 90 decibels, the decibel value is not reliable. Figure 4.3 clearly
illustrates that the sound pressure level equation can not accurately predict the sound
levels of tools because of environmental factors.
The numbers from Figure 4.1 also show that the computed sound levels do not
take into account the environment where the sounds are produced. The computed value
had a 29.7 decibel drop from 6 inches to 15 feet, and the measured tools had a decibel
drop between 17.3 decibels to 18.3 decibels. Clearly the materials of the room, the
concrete floors and the concrete masonry unit walls, reflected the sound creating a lower
decibel drop over a distance than anticipated. This is important, because the sound
pressure level equation obviously can not be used to accurately estimate the sound levels
in an area. The difference in the computed values to the actual readings was over ten
decibels, which as explained earlier, is a significant amount.
When comparing the indoor decibel readings to the outdoor decibel readings the
initial reading for the outdoor measurements are slightly lower than the indoor
measurements, but as one travels from the source of sound, the decibel levels are
different. The outdoor decibel levels have a larger decibel drop than the same distant
measurements indoors. The outdoor measurement have a larger drop in decibels than
when indoors, probably because of the sound reflective qualities of the concrete masonry
47
unit walls and concrete floor within the room where the testing was done. Therefore one
can conclude that sound will dissipate in a shorter distant when outdoors in comparison to
an enclosed room.
There are also differences in decibel levels when the tool is applied to wood in
comparison to when the tool is just running and not applied to wood. Tools that actually
cut wood, such as the circular saws and the reciprocating saw, had a significant increase
in decibel levels when cutting wood in comparison to when the tool was turned on and
not cutting wood. Other tools such as the belt sander had a higher decibel levels when the
tool was just running compared to when the tool was actually applied to wood. The router
decibel levels were essentially equal when simply running and when applied to wood.
Therefore when the sound level emissions of a tool are being evaluated, the tool should
be tested with the power turned on and not applied to wood, and when the tool is turned
on and applied to wood.
In the evaluation of the study there is a very clear conclusion, there are very
apparent dangers that exist pertaining to potential hearing loss with the use of power
tools. All of the conventional portable carpenter power tools exceeded the decibel level
that would classify the tool as safe, except for the drill which was the only tool evaluated
that was battery powered. Therefore all workers working on a jobsite where power tools
are being used (almost all jobsites) should be aware of the danger of permanently
damaging their hearing, and take the proper precautions of protecting against that danger.
CHAPTER 6
RECOMMENDATIONS
Practice recommendations. Contractors and workers need to be more aware of
the dangers of elevated noise levels on construction projects in order to stop the excessive
amount of hearing damage among construction workers. Contractors need to constantly
test the jobsites. Signs should be posted that communicate to the workers the dangers of
the noise levels on the jobsite, and the benefits of wearing hearing protection. For
example a sign may suggest that workers wear hearing protection all the time, or that
hearing protection be worn when specific tools are operating and the workers are within
stipulated distances of the operating tools. By listing the decibel levels of listed tools
workers will begin to understand the decibel levels that are dangerous and what tools put
them at risk.
The safest practice though would be to incorporate hearing protection into the
jobsites, the way work boots and hard hats are currently used on jobsites. There are no
large jobsites in the country where a worker can walk onto the project without a pair of
work boots and a hard hat. This is true for two reasons, the workers well being and the
reduced cost of insurance for the contractor. The same should be true for hearing
protection. It is well established that there is high risk of hearing damage on a
construction jobsite, and there is an easy way to prevent damage, by wearing hearing
protection. If the workers have better hearing not only is it better for their health, but it
48
49
creates a safer jobsite. Imagine the danger if a worker cannot hear a warning or
instructions in a critical situation.
In the author’s opinion, to ensure the safety of workers in construction, hearing
protection should be worn at all times on the jobsites. There are several options for
hearing protection. The most popular form of hearing protection on many jobsites is
expandable foam plugs. The plugs are disposable and are only used once before being
thrown away. The plugs are made from a foam material that is rolled or squeezed and
then placed in the user’s ear. Once in the ear, the foam expands to fit the individual’s ear,
and protects against noise. Pre-molded reusable plugs are an option as well; these plugs
are made from a hard rubber or plastic material. These plugs are intended for numerous
uses and are intended for repeated use. The plugs come in various sizes to provide the
best fit. Earmuffs are another option of hearing protection, the earmuffs entirely cover the
ears of the workers and completely block out sound. The muffs are mounted on a head
band and some can be affixed directly to the hard hat. The earmuffs are a very effective
form of hearing protection, but many workers complain that the earmuffs can be hot and
cumbersome. The last option in hearing protection is canal caps. Canal caps are small
plugs that are placed in the ears. The plugs are attached to a hard plastic band so that
when not being used the worker can comfortably place the caps around his or her neck.
All of these hearing protection options will protect the worker from permanent hearing
damage. The best option is the one that the worker will wear. The contractor should ask
his/her employees which hearing protection is most comfortable to the workers, so the
workers will be more likely to wear the hearing protection.1
1
http://www.cdc.gov/niosh/topics/noise/
50
Research recommendations. There are numerous studies that should be
performed to better understand the vastly misunderstood subject of hearing safety within
the construction industry.
A study should be performed that would identify the current methods that
contractors use to ensure that their workers’ hearing is protected. This includes the
methods the contractors use to reduce noise on their projects as well the programs that are
implemented to promote the wearing of hearing protection by the workers.
A study should be performed that measures the decibel levels on actual jobsites.
This would enable the evaluation of noise levels on jobsites and increase the knowledge
of noise levels on jobsites, which could potentially increase the level of safety for the
workers.
A study should be performed that tests worker’s hearing in the construction
industry. New workers’ hearing should be tested and compared to the tested hearing of
veteran construction workers. The veteran construction workers’ hearing should also be
compared with the hearing test data of the general population of the same age group.
Therefore any difference in hearing between the new construction workers and the older
construction workers can be determined if it is due to age or work environment.
A survey of construction workers should be performed that would question their
understanding of the dangers of noise levels on the jobsite. The survey should also
question the workers about which form of hearing protection the workers are most
comfortable wearing.
LIST OF REFERENCES
Asfahal, C. Ray, Industrial Safety and Health Management. Upper Saddle River, NJ:
Prentice Hall, 2004
Beranek, L.L. Noise and Vibration Control Engineering Principles and Applications.
Toronto: John Wiley & Sons
Brooks, Christopher. Architectural Acoustics. Jefferson, NC: Brooks, 2003
Egan, David M. Architectural Acoustics. NY: McGraw Hill 1988
Goetsch, David L. Occupational Safety and Health for Technologists, Engineers, and
Managers. Upper Saddle River, NJ: Prentice Hall, 1996
Harris, Cyril. Handbook of Acoustical Measurements and Noise Control. New York:
McGraw Hill, 1991
Herrinton, Thomas N. Occupational Injuries Evaluation, Management, and Prevention.
New York: Mosby, 1995
Kutruff, Heinrich. Room Acoustics: London: Spon, 2002
Mechel, Fridiolin. Formulas of Acoustics. Berlin: Springer, 2002
National Institute for Occupational Safety and Health, January 15, 2004.
http://www.cdc.gov/niosh/pdfs/2001-157.pdf
National Institute for Occupational Safety and Health, January 15 2004.
http://www.cdc.gov/niosh/topics/noise/
Occupational Safety and Health Administration, January 16, 2004.
http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARD
S&p_id=10625
Radio Shack, January 17, 2004. www.radioshack.com
51
BIOGRAPHICAL SKETCH
The author of this thesis, Gregory D. Callahan, is completing his Master of Science
in Building Construction degree at the University of Florida. The author began his studies
at the University of Florida in August of 2002. Prior to attending graduate school Mr.
Callahan received a Bachelors of Art from Boston College in 1996. At Boston College
the author’s major was art history.
52