Noise Levels of Common Construction Power Tools

Home , Carpenter (theatre), Router (woodworking)

NOISE LEVELS OF COMMON CONSTRUCTION POWER TOOLS

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

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

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

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

Gregory Callahan

May, 2004

Chair: Jimmie Hinze Major Department: Building Construction

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

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.

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 d1/d2 0.5 0.4 0.4 2.5 7.5 2.5 decibel drop -6.02 -7.95 -7.95 7.95 17.50 7.95

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)(i)

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.

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

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:

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

C 13’

6’ Tool H D F J 30’

6’

E 13’ Operator

6’ A= location of sound reading 6” from tool. 15’ 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).

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’ Tool 16” from corner

F C

6’ D A= location of sound reading 6” from tool. (6’ from tool) E 15’ B= sound reading taken at 24” above tool (ear level of ope rator)

H 30’ G Operator (30’ from tool)

40’

Figure 3-3 Corner of Room Sound Level Measurements

Operator C 13’

6’ G D 30’ (30’ from tool) (6’ from tool) 6’ E 13’

Tool A= location of sound reading 6” from tool. B= sound reading taken at 24” above tool (ear level of operator) 40’

Figure 3-4 Indoor Against Wall Sound Level Measurement

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).

G A= location of sound reading 6” from tool. B= sound reading taken at 24” C above tool (ear level of operator) 15’

6’ Tool H D F J

6’

Nearest E 15’ Building 81’ Operator feet from Building I

6’ 6’

15’ 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).

Building

Tool

F C A= location of sound reading 6” from tool. D 6’ B= sound reading taken at 24” Operator E 15’ above tool (ear level of operator) 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).

A= location of sound reading 6” from tool. B= sound reading taken at 24” above tool (ear level of operator) Tool

15 ’ E

6’ D G (6’ from tool) 6’ (30’ from tool) C 15’

Op erator F

Building

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 90

Computed PC circular saw l

e Saws All 80 Router

Decib Drill Beltsander BD circular saw

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 98

l 96 6' front

be 6' back i 94 6' Left 6' right Dec 92 90 88 86 84 82 80 78 Center of Room Indoor against Indoor Corner Open Area Outdoor Against Outdoor Corner Wall Outdoor 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

100 l

e Not Cutting at 24" b i

c Cutting 24" De 95

85 Center of Indoor Against Indoor against Open Area Outdoor Outdoor Room Wall Corner Outdoor Against wall 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.

103

101

Decibel 97

Porter Cable Saw at 24" 95 2 Circular Saws Computed

87 Center of Room Indoor against Indoor Corner Open Area Outdoor Against Outdoor Corner Wall Outdoor wall 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 Reading Reading Reading Circular Saw: Center of Room 1 2 3 Average Computed Location A 100 101 102 101.0 101 A' 115 115 114 114.7 114.7 B 92 93 93 92.7 88.96 B' 108 109 108 108.3 102.66 C 90 89 90 89.7 79.42 C' 96 95 95 95.3 93.12 D 85 84 85 84.7 79.42 D' 94 95 96 95.0 93.12 E 81 81 81 81.0 79.42 E' 95 96 97 96.0 93.12 F 88 89 88 88.3 79.42 F' 98 98 98 98.0 93.12 G 84 83 84 83.7 71.5 G' 91 92 91 91.3 85.2 H 80 80 81 80.3 71.5 H' 95 94 95 94.7 85.2 I 81 81 81 81.0 71.5 I' 95 95 95 95.0 85.2 J 83 84 84 83.7 71.5 J' 92 92 92 92.0 85.2

Table 4-2. Computed Decibel Levels Computed No Range d1 0.5 0.5 0.5 d2 2 6 15 d1/d2 0.25 0.083333 0.0333333 - decibel drop -12.0412 21.58362 -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.

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 Reading Reading Reading Room 1 2 3 Average Location A 101 102 102 101.7 A' 115 116 114 115.0 B 92 94 94 93.3 B' 109 109 108 108.7 C 91 90 90 90.3 C' 97 95 96 96.0 D 85 86 86 85.7 D' 95 97 96 96.0 E 82 80 83 81.7 E' 96 96 98 96.7 F 90 91 92 91.0 F' 99 98 99 98.7 G 84 85 83 84.0 G' 92 93 91 92.0 H 81 81 81 81.0 H' 97 96 95 96.0 I 82 82 81 81.7 I' 95 96 95 95.3 J 85 84 85 84.7 J' 93 93 92 92.7

Table 4-4. Saws All Center of Room Saws All: Center of Room Reading 1 Reading 2 Reading 3 Average Location A 98 98 98 98.0 A' 101 101 101 101.0 B 89 88 89 88.7 B' 92 91 91 91.3 C 85 84 86 85.0 C' 87 88 87 87.3 D 85 86 85 85.3 D' 81 81 82 81.3 E 86 85 85 85.3 E' 86 86 87 86.3 F 85 85 85 85.0 F' 88 89 88 88.3 G 80 79 80 79.7 G' 78 79 79 78.7 H 78 79 78 78.3 H' 76 77 76 76.3 I 78 79 78 78.3 I' 80 79 79 79.3 J 79 80 80 79.7 J' 82 82 82 82.0

Table 4-5. Router Center of Room Router: Center of Room Reading 1 Reading 2 Reading 3 Average Location A 102 103 103 102.7 A' 102 101 101 101.3 B 99 98 99 98.7 B' 100 101 101 100.7 C 89 89 90 89.3 C' 100 101 101 100.7 D 91 92 92 91.7 D' 93 94 93 93.3 E 88 88 88 88.0 E' 90 91 90 90.3 F 90 91 90 90.3 F' 94 95 95 94.7 G 84 85 85 84.7 G' 87 88 88 87.7 H 84 84 84 84.0 H' 87 88 88 87.7 I 85 86 85 85.3 I' 87 87 87 87.0 J 88 89 88 88.3 J' 88 89 89 88.7

Table 4-6. Drill Center of Room Drill: Center of Room Reading 1 Reading 2 Reading 3 Average Location A 76 77 77 76.7 A' 83 83 83 83.0 B 71 72 72 71.7 B' 79 78 79 78.7 C 64 65 64 64.3 C' 70 71 70 70.3 D 66 66 66 66.0 D' 70 71 72 71.0 E 64 64 64 64.0 E' 68 68 69 68.3 F 68 68 69 68.3 F' 71 71 71 71.0 G 60 59 59 59.3 G' 63 62 63 62.7 H 59 60 59 59.3 H' 62 61 62 61.7 I 60 59 59 59.3 I' 60 61 61 60.7 J 59 59 60 59.3 J' 61 61 61 61.0

Table 4-7. Two Circular Saws Center of Room

Both Circular Saws Center of Room Reading 1 Reading 2 Reading 3 Average Location A 110 111 109 110.0 B 96 97 96 96.3 C 92 93 91 92.0 D 88 89 88 88.3 E 99 99 97 98.3 F 88 89 89 88.7 G 84 85 86 85.0 H 90 91 92 91.0 J 89 90 89 89.3

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

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 Reading 1 Reading 2 Reading 3 Average Jigsaw Location A 111 112 113 112.0 Jigsaw Location B 99 100 99 99.3 Planer Location A 118 118 117 117.7 Planer Location B 96 96 99 97.0 Grinder Location A 118 118 121 119.0 Grinder Location B 108 107 107 107.3 Carver Location A 82 84 89 85.0 Carver Location B 72 72 77 73.7

Table 4-9. Beltsander Center of Room Beltsander: Center of Room Reading 1 Reading 2 Reading 3 Average Location A 108 109 108 108.3 A' 111 111 112 111.3 B 103 102 104 103.0 B' 97 97 98 97.3 C 93 93 93 93.0 C' 94 93 92 93.0 D 93 94 93 93.3 D' 94 95 95 94.7 E 95 96 96 95.7 E' 92 93 92 92.3 F 97 98 97 97.3 F' 92 92 93 92.3 G 88 87 88 87.7 G' 85 86 86 85.7 H 88 88 88 88.0 H' 85 84 86 85.0 I 91 91 92 91.3 I' 88 88 89 88.3 J 91 91 90 90.7 J' 90 89 90 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;

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 Reading Room Reading 1 2 Reading 3 Average Location A 103 103 104 103.3 A' 113 114 114 113.7 B 99 99 100 99.3 B' 109 108 109 108.7 C 92 92 91 91.7 C' 101 100 101 100.7 D 88 88 87 87.7 D' 103 104 103 103.3 E 91 90 91 90.7 E' 98 99 98 98.3 F 80 80 80 80.0 F' 93 93 92 92.7 G 79 79 80 79.3 G' 89 88 89 88.7 H 81 81 81 81.0 H' 89 90 90 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

Table 4-11. Saws All Corner of Room Saws All: Corner of Room Reading 1 Reading 2 Reading 3 Average Location A 94 93 96 94.3 A' 92 93 93 92.7 B 88 89 88 88.3 B' 87 87 88 87.3 C 79 80 79 79.3 C' 81 81 80 80.7 D 77 77 78 77.3 D' 79 80 80 79.7 E 80 80 80 80.0 E' 80 81 81 80.7 F 75 76 76 75.7 F' 75 74 74 74.3 G 69 69 70 69.3 G' 70 71 70 70.3 H 71 71 71 71.0 H' 72 71 72 71.7

Table 4-12. Router Corner of Room Router: Corner of Room Reading 1 Reading 2 Reading 3 Average Location A 101 102 100 101.0 A' 102 102 100 101.3 B 92 93 94 93.0 B' 94 95 94 94.3 C 88 88 89 88.3 C' 90 92 90 90.7 D 84 85 85 84.7 D' 88 88 88 88.0 E 84 84 84 84.0 E' 91 91 92 91.3 F 80 84 80 81.3 F' 77 78 78 77.7 G 74 75 75 74.7 G' 75 74 75 74.7 H 75 75 74 74.7 H' 77 78 77 77.3

Table 4-13. Drill Corner of Room Drill: Corner of Room Reading 1 Reading 2 Reading 3 Average Location A 73 73 72 72.7 A' 75 75 76 75.3 B 66 66 65 65.7 B' 70 72 71 71.0 C 62 62 63 62.3 C' 62 63 64 63.0

Table 4-13 Continued Drill: Corner of Room Reading 1 Reading 2 Reading 3 Average D 60 59 60 59.7 D' 61 62 60 61.0 E 61 62 60 61.0 E' 61 60 62 61.0 F 50 52 50 50.7 F' 54 55 54 54.3 G 54 55 54 54.3 G' 54 55 54 54.3 H 60 59 60 59.7 H' 53 53 53 53.0

Table 4-14. Two Circular Saws Corner of Room 2 Circular Saws Corner Room Reading 1 Reading 2 Reading 3 Average Location A 109 110 108 109.0 B 100 101 100 100.3 C 97 98 99 98.0 D 99 100 98 99.0 E 95 96 95 95.3 F 88 88 88 88.0 G 87 88 87 87.3 H 87 88 87 87.3

Table 4-15. Beltsander Corner of Room Beltsander: Corner of Room Reading 1 Reading 2 Reading 3 Average Location A 109 110 108 109.0 A' 101 101 102 101.3 B 98 99 99 98.7 B' 89 90 89 89.3 C 89 89 90 89.3 C' 84 84 85 84.3 D 85 85 86 85.3 D' 83 84 84 83.7 E 88 88 89 88.3 E' 85 85 86 85.3 F 79 78 79 78.7 F' 79 78 79 78.7 G 78 77 77 77.3 G' 74 75 74 74.3 H 78 78 79 78.3 H' 77 77 78 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 Reading 1 Reading 2 Reading 3 Average Location A 101 101 101 101.0 A' 113 114 115 114.0 B 95 94 95 94.7 B' 107 108 108 107.7 C 89 90 89 89.3 C' 91 91 92 91.3 D 97 97 98 97.3 D' 96 95 96 95.7 E 91 91 92 91.3 E' 100 100 100 100.0 F 83 82 83 82.7 F' 93 92 93 92.7 G 79 80 79 79.3 G' 89 90 89 89.3 H 81 82 81 81.3 H' 95 94 95 94.7

Table 4-17. Drill Against Wall Indoors Drill: Middle of Wall Reading 1 Reading 2 Reading 3 Average Location A 80 79 80 79.7 A' 84 84 85 84.3 B 72 73 72 72.3 B' 76 77 76 76.3 C 62 61 62 61.7 C' 70 70 69 69.7 D 58 58 59 58.3 D' 68 67 68 67.7 E 65 65 65 65.0 E' 70 69 71 70.0 F 56 56 56 56.0 F' 64 64 64 64.0 G 56 55 56 55.7 G' 57 57 58 57.3 H 59 60 59 59.3 H' 68 66 66 66.7

Table 4-18. Saws All Against Wall Indoors Saws All: Middle of Wall Reading 1 Reading 2 Reading 3 Average Location A 98 98 99 98.3 A' 93 94 94 93.7 B 90 90 89 89.7 B' 89 90 90 89.7 C 79 79 79 79.0 C' 83 82 82 82.3 D 82 83 83 82.7 D' 83 83 83 83.0 E 84 84 84 84.0 E' 85 86 85 85.3 F 74 74 75 74.3 F' 80 80 81 80.3 G 73 74 73 73.3 G' 75 76 75 75.3 H 81 81 80 80.7 H' 83 84 83 83.3

Table 4-19. Beltsander Against Wall Indoors Beltsander: Middle of Wall Reading 1 Reading 2 Reading 3 Average Location A 115 114 115 114.7 A' 109 110 110 109.7 B 102 103 103 102.7 B' 103 103 104 103.3 C 93 93 94 93.3 C' 91 91 92 91.3 D 92 92 92 92.0 D' 95 95 94 94.7

Table 4-19 Continued Beltsander: Middle of Wall Reading 1 Reading 2 Reading 3 Average E 97 98 99 98.0 E' 95 95 95 95.0 F 87 87 88 87.3 F' 87 88 87 87.3 G 85 86 85 85.3 G' 85 85 86 85.3 H 93 94 93 93.3 H' 92 92 92 92.0

Table 4-20. Router Against Wall Indoors Router: Middle of Wall Reading 1 Reading 2 Reading 3 Average Location A 104 104 105 104.3 A' 106 106 105 105.7 B 98 99 99 98.7 B' 102 102 101 101.7 C 89 88 88 88.3 C' 94 93 93 93.3 D 92 92 93 92.3 D' 92 93 93 92.7 E 93 93 92 92.7 E' 90 90 91 90.3 F 82 81 81 81.3 F' 86 86 87 86.3 G 78 78 79 78.3 G' 83 83 84 83.3 H 89 89 90 89.3 H' 87 88 88 87.7

Table 4-21. Two Circular Saws Against Wall Indoors 2 Circular Saws Middle of Wall Inside Reading 1 Reading 2 Reading 3 Average Location A 110 112 112 111.3 B 98 98 99 98.3 C 94 95 96 95.0 D 90 91 90 90.3 E 98 97 99 98.0 F 87 89 88 88.0 G 88 89 90 89.0 H 90 89 89 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 Reading 1 Reading 2 Reading 3 Average Location A 99 98 100 99.0 A' 112 113 112 112.3 B 88 88 89 88.3 B' 100 99 100 99.7 C 82 82 81 81.7 C' 87 88 88 87.7 D 73 74 73 73.3 D' 91 92 91 91.3 E 79 80 80 79.7 E' 92 93 93 92.7 F 80 81 81 80.7 F' 90 90 89 89.7 G 73 73 72 72.7 G' 81 82 82 81.7 H 68 67 67 67.3 H' 80 81 80 80.3 I 72 72 73 72.3 I' 90 89 89 89.3 J 72 72 73 72.3 J' 81 82 82 81.7

Table 4-23. Black and Decker Circular Saw Open Field Readings B&D Circular Saw : Outside Reading 1 Reading 2 Reading 3 Average Location A 100 101 101 100.7 A' 110 109 110 109.7 B 87 86 87 86.7 B' 102 103 102 102.3 C 84 84 83 83.7 C' 91 92 91 91.3 D 77 77 76 76.7 D' 82 83 83 82.7 E 87 87 86 86.7 E' 95 95 96 95.3 F 88 89 88 88.3 F' 90 91 90 90.3 G 75 76 77 76.0 G' 83 84 83 83.3 H 67 66 67 66.7 H' 81 82 81 81.3 I 74 74 75 74.3 I' 93 94 94 93.7 J 75 75 74 74.7 J' 83 83 84 83.3

Table 4-24. Two Circular Saws Open Field Readings 2 Circular Saws : Outside Reading 1 Reading 2 Reading 3 Average Location A 98 99 99 98.7 B 88 88 89 88.3 C 82 83 82 82.3 D 81 80 81 80.7 E 88 88 89 88.3 F 87 87 88 87.3 G 77 77 76 76.7 H 76 76 75 75.7 I 77 77 78 77.3 J 77 77 76 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 Reading 1 Reading 2 Reading 3 Average Location A 102 103 102 102.3 A' 126 125 123 124.7 B 98 99 98 98.3 B' 108 109 110 109.0 C 91 92 92 91.7 C' 104 104 103 103.7 D 87 88 87 87.3 D' 103 104 103 103.3 E 91 90 91 90.7 E' 108 109 107 108.0 F 84 84 85 84.3 F' 96 96 97 96.3 G 82 81 82 81.7 G' 99 98 98 98.3 H 81 82 82 81.7 H' 97 98 98 97.7

Table 4-26. Two Circular Saw Outdoor Corner 2 Circular Saws Corner Outside Reading 1 Reading 2 Reading 3 Average Location A 109 110 109 109.3 B 103 102 103 102.7 C 99 99 98 98.7 D 93 94 94 93.7 E 99 100 99 99.3 F 89 89 89 89.0 G 88 87 87 87.3 H 87 88 87 87.3

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 Reading Circular Saw: Middle of Wall Outside Reading 1 2 Reading 3 Average Location A 101 102 100 101.0 A' 119 120 119 119.3 B 89 89 88 88.7 B' 106 107 107 106.7 C 74 75 74 74.3 C' 98 98 97 97.7 D 74 75 74 74.3 D' 97 97 98 97.3 E 82 81 81 81.3 E' 108 108 109 108.3 F 75 75 75 75.0 F' 90 89 90 89.7 G 69 68 69 68.7 G' 94 93 93 93.3 H 75 75 76 75.3 H' 98 99 99 98.7

Table 4-28. Two Circular Saws Outside Against Wall 2 Saws: Middle of Wall Outside Reading 1 Reading 2 Reading 3 Average Location A 109 110 110 109.7 B 100 101 101 100.7 C 94 94 95 94.3 D 88 88 89 88.3 E 94 96 95 95.0 F 87 87 86 86.7 G 81 80 81 80.7 H 88 88 87 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/

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

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.