36 PROFESSIONAL SAFETY NOVEMBER 2007 www.asse.org

Noise & Hearing


Protection

Development of two training exercises for drillers 

By Edward A. Barrett and Roberta A. Calhoun 

MORE THAN 30 MILLION EMPLOYEES each year 

are exposed to hazardous occupational noise, and 

approximately one-third of them develop permanent 

hearing loss (NSC, 2000). Possible explanations for 

the latter statistic include worker regard for noise as 

a mere nuisance rather than as an occupational safety and health hazard, 

and consequent neglect

of established protective

measures (e.g., hearing

protection); lack of

knowledge concerning

noise; improper use

of hearing protection;

worker indifference;

and inadequate training

(Bauer & Babich, 2004). 

Many drill rigs generate high sound levels,

which vary according to

the type of machine, its

location with respect to

the physical surroundings, and the location of

the sound measured

around the rig. A Photo 1: Impact noise: Metal on metal. 

NIOSH study measured noise output from several 

types of drill rigs during field investigations (Ingram 

& Matetic, 2003). Two types of data were recorded— 

the actual noise generated by the drill rig at various 

positions around the rig and 

the noise to which the drill 

operator was exposed during 

the drilling cycle. For the latter, sound level measurements 

up to 120 dBA were recorded 

while hammering casing

(metal on metal) in drilling a 

water well (Photo 1). 

Several types of administrative controls exist to

address worker exposure to 

loud drill rig noise. Rotating 

duties to decrease exposure time and posting 

warning signs in high-noise work areas are two 

such controls. 

Another is the use of hearing protection. Worker 

use of hearing protection has been disappointing, 

however. One study by the University of Michigan 

found that construction 

workers used earplugs 

and earmuffs only between 36% and 61% of 

the time that they were 

necessary (Lusk & Kerr, 

1998). In a 2001 study, 

OSHA reported a relatively low rate of 

30.4% for use of earplugs 

among construction 

workers (Walker, 2001). 

Why are rates for 

hearing protection use 

so low? One explanation may be workers’ 

lack of concern for noise 

in the workplace. They 

expect workplace noise 

to be a loud and inevitable nuisance and, therefore, accept it as part of 

the job. As a result, they disregard proven measures 

that can protect their hearing. Other workers may 

use hearing protection, but do so improperly. They 

may misguidedly remain in high-noise areas for 

extended periods thinking they are protected when 

in fact they are not. Other reasons for low use 

and/or misuse of hearing protection include poor 

education, lack of awareness and inadequate training (Nash, 2003). 

To address the training issue, NIOSH developed 

two exercises from which drillers can learn about 

noise, hearing loss and hearing protection. The first 

is an invisible ink exercise, titled “Drill Rig

Incident” (DRI) (Photo 2); the second is a 3-D slide 

reel training aid, “Wearing Hearing Protection 

Properly” (WHPP) (Photo 3). DRI is an instructor­
www.asse.org NOVEMBER 2007 PROFESSIONAL SAFETY 37

led training exercise for use with small groups of 

workers, while WHPP is a self-teaching exercise for 

use without an instructor. 

Invisible ink exercises, sometimes supplemented 

with 3-D slide reels, have been used effectively for 

many other mining safety issues, including machine 

guarding, ground falls, first aid and self-rescue 

(Cole, Wiehagen, Vaught et al., 2001). These methods 

are more interactive than standard lecture or paperand-pencil exercises, and less technology-dependent 

than computer-based training exercises. Feedback 

about the techniques is generally positive. For example, Cole, et al. (2001) reported that 60% of respondents indicated that these types of exercises are 

better than traditional training methods and 40% 

indicated the exercises were comparable. No negative responses were reported. The exercises are readily available and highly used by mining safety and 

health trainers (with thousands of packages distributed by NIOSH, MSHA and online at www.cdc 

.gov/niosh/mining/products). 

Development of Training Exercises 

The initial step in developing the exercises was to 

identify key concepts (subject areas) to be incorporated into the training program. In selecting content 

material, the literature on noise and hearing protection was searched for information that would 

address the issues and concerns discussed earlier. 

First, an annotated bibliography consisting of both 

descriptive and conclusive reports was prepared. 

As articles were reviewed, relevant concepts were 

documented and categorized as either a) background and effects or b) driller and employer 

responsibilities. Background and effects included 

the following subject areas: sources of noise; danger 

of noise exposure to drillers; population at risk; 

safety and health effects of noise exposure; types of 

noise exposure; and OSHA regulations for driller 

exposure to noise. Driller and employer responsibilities included these subject areas: role of drillers in 

preventing noise-induced hearing loss; role of 

employers in preventing noise-induced hearing loss 

to drillers; warning signs; anticipation of exposure 

to noise at drill sites; evaluation of noise hazards at 

drill sites; prevention of exposure to drillers; and 

control of noise hazards at drill sites. 

Several topics in these various subject areas were 

discussed with content experts and safety practitioners and the following were chosen to be incorporated into the exercises: 

•basic facts about noise and hearing loss; 

•indications of hearing loss; 

•recognition of excessive workplace noise levels; 

•dealing with loud drill rig noise; 

•awareness of personal hearing loss; 

•wearing hearing protection properly; 

•accepting responsibility for protecting hearing 

on and off the worksite. 

A first draft of DRI and six demo 3-D slide reels 

were prepared then authenticated by various industry, academia and MSHA representatives. Their 

comments and recommendations were considered 

and selectively integrated into the exercises. 

A pilot test study was conducted to make any 

necessary changes before full-scale field testing. 

Instructional materials and evaluation procedures 

(namely, pretest/posttest questions) were used in a 

trial run with a small number of subjects. Pilot tests 

were conducted with representatives from industry, 

MSHA, NIOSH and academia. Based on comments 

from participants, the exercise content was modified, particularly the use of appropriate terminology 

for drilling equipment, work processes and workplace conditions. After considering all recommendations and suggestions, those that were believed to 

improve the exercises were incorporated into the 

final version. 

Invisible Ink Exercise 

The invisible ink exercise begins with background 

information about a drilling crew and a job they are 

trying to complete. This is followed by the description of a problem scenario for the drill crew foreman. 

The trainee assumes the role of the foreman and sets 

out to handle the problem. After reading the background information provided, the trainee proceeds 

to answer a series of 11 questions (A through K) in 

sequence. Each question has at least one correct 

answer and some have multiple correct answers. 

After reading a question and selecting an answer, 

the trainee turns to the answer sheet that contains 

Clockwise from top left: Photo 2: Invisible ink training exercise example. 

Photo 3: 3-D viewer and slide reel. Photo 4: Driller looks at 3-D reel 

before his shift. 

Abstract: Drillers and 

their helpers are 

among the more than 

30 million American 

workers who are regularly subjected to 

excessive workplace 

noise. Approximately 

one-third of these 

employees eventually 

develop permanent 

hearing loss. One 

explanation for this 

problem is inadequate 

training. To address 

this issue, NIOSH developed two training 

exercises to inform 

drillers about noise, 

hearing loss and proper use of hearing protection. This article 

reviews the development and evaluation 

of these exercises and 

discusses their use and 

availability. 
38 PROFESSIONAL SAFETY NOVEMBER 2007 www.asse.org

sets of empty brackets corresponding to answer 

choices. The trainee then uses a special developing 

ink pen between the appropriate brackets to reveal 

feedback information that was printed using invisible ink. From the feedback, the trainee learns 

whether the answer is correct or not, and why. The 

feedback also provides valuable additional information from which trainees can learn more about concepts being taught in the exercise. 

3-D Slide Reel Training Aid 

The 3-D slide reel training aid contains colorful 

visuals with embedded words in each stereo scene. 

The scenes realistically illustrate the proper use of 

two types of hearing protection—foam earplugs and 

earmuffs. As part of their training, workers are asked 

to look at the 3-D reel as a reminder of how each type 

of protection should be properly worn. This may be WHPP: Scene 2 

l In the 3-D slide reel training aid example shown 

in the “WHPP Example” sidebar, a driller “rolling 

and squeezing a foam earplug” is shown. The discussion notes are intended to provide additional 

helpful information about preparing foam earplugs 

done anywhere, even in a pickup truck at the dril

site before starting a workday (Photo 4, p. 37). 

Examples from DRI & WHPP 

DRI: Question G 

The sidebar (“DRI Example”) shows an example 

from DRI. The six questions leading up to this 

question in the DRI scenario relate to the following 

incident involving a driller helper: “Eager to prevent a similar incident from occurring to other 

workers, the company safety manager, Rip, decides 

to develop a training program to teach workers 

about noise and hearing protection.” As part of this 

company training program, Question G points out 

that workers should be capable of determining for 

themselves whether they have a hearing loss by 

paying attention to various cues. Question G is followed by a series of six answers, five of which are 

correct. The answers within the brackets are the 

actual words that are printed using invisible ink. 

Instructor discussion notes follow the answers. The 

discussion notes serve two purposes—to provide 

additional subject information for use by a trainer, 

if desired, and to explain the rationale for some of 

the answer choices.

for insertion. 

Evaluation of Training Exercises 

To determine the effectiveness of DRI for meeting 

its instructional objectives, a split-group 

pretest/posttest experiment and an eightitem Likert scale self-reporting measure 

were administered to 180 participants. 

The study group consisted of persons who 

have varying levels of actual hands-on 

drilling experience. The experimental 

design has strong internal validity, as persons were randomly selected to take either 

a pretest or, following training, a posttest, 

but not both. Those who took the posttest

scored significantly higher (p < .01), and it

was concluded that the improved score 

was a result of the training. 

The self-reporting measure was used to 

determine the validity and utility of the 

exercise. More than 73% of the participants indicated that they “learned something new from the exercise” and nearly 

90% said that they “will use some of the 

ideas presented to protect their hearing.” 

The utility of the exercise was also high, as 

approximately 90% of the participants 

reported that “the way the material was 

presented is a good way for me to learn.” 

To determine the effectiveness of 

WHPP, 101 participants were given an 

eight-question, multiple-choice pretest 

and posttest immediately before and after 

viewing the 3-D slide reel. This study 

group also included persons who have a 

broad range of hands-on drilling experience. Again, participants scored significantly higher on the posttest (p < .01), and

it was concluded that the objectives of the 

instruction were achieved. 

DRI Example 

Question G 

You think that the program should teach workers how to recognize signs of 

hearing loss. You want to suggest ways that they can judge for themselves if 

their hearing is bad. Which of the following would you recommend that Rip 

include in the training? (Select as MANY as you think are correct) 

30. They often ask people to repeat what they are saying. 

31. Someone tells them they talk too loud. 

32. They have trouble hearing normal conversation. 

33. They complain about people mumbling. 

34. They have constant ringing or buzzing in their ears. 

35. Others complain that the TV is too loud. 

30. [Correct. If this happens most of the time, it’s one sign that a person may ]	 

[have a hearing loss. ] 

31. [This doesn’t necessarily mean they have a hearing problem. A loud	 ] 

[voice may be normal for some people. Try again. ] 

32. [Correct. In most cases, this points to a hearing loss.	 ] 

33. [Correct. With a hearing loss, it is difficult to hear all of the sounds that 	 ] 

[are spoken. Talk may sound like people are mumbling. ] 

34. [Correct. Called tinnitus, this is a classic symptom of hearing loss. ] 

35. [Correct.	 ] 

Discussion (from the instructor’s discussion notes) 

The correct answers are 30, 32, 33, 34 and 35. It’s important for workers to be 

able to assess their own individual level of hearing. They are more likely to protect the hearing they have left when they know and accept the fact that some of 

their hearing is gone. Workers need to be aware that one sign of a hearing loss is 

asking others to repeat what has been said (30). Problems hearing normal conversation (32), complaints about people mumbling (33) and having to turn up 

the volume on the TV (35) are also signs of hearing loss. Constant buzzing or 

ringing in the ears, called tinnitus (34), can also indicate a hearing loss. 
.asse.org NOVEMBER 2007 PROFESSIONAL SAFETY 39

WHPP Example 

Scene 2 

Before inserting foam earplugs, they should be rolled into a thin crease-free cylinder. To get the 

diameter of the cylinder as small as possible and 

crease-free, begin by squeezing the earplug lightly as it is being rolled between your forefinger 

and thumb. Then gradually apply progressively 

greater pressure as the plug becomes more tightly 

compressed. 

The earplug may also be rolled in a person’s 

palms to achieve the thin, crease-free cylinder. This 

may be necessary for the person who has small or 

thin fingers, in which case the cylinder could end 

up in a distorted “barbell” shape. 

A mistake that some workers make is to unintentionally roll the foam earplug into a ball or cone, 

instead of a cylinder. This results in a configuration 

that cannot be inserted very far into the ear canal 

and, therefore, cannot provide effective protection. 

www

Table 1 

Demographics of Subjects	 

Pretest group Posttest group 

n M SD n M SD 

Age 103 42.0 11.6 71 43.5 10.1 

Years’ experience 96 13.3 12.1 96 13.3 10.0 

Table 2 Table 2 

Independent Samples t test 

n M SD t-value p-value 

Pretest group 108 18.87 2.24	 

4.11 < .0001 

Posttest group 72 20.22 2.04 

Drill Rig Incident	 pretest or posttest. No one in this sample completed 

DRI was evaluated to determine its effectiveness both the pretest and posttest. 

for teaching workers about noise, hearing loss and The rationale for dividing the sample was to 

hearing protection. A sample of 180 people participat- ensure that those completing the posttest would not 

ed in a field experiment that consisted of two parts. In be sensitized to the questions by first taking the 

the first part, participants completed either a pretest pretest, which might have, thereby, led to incorrect 

before working the exercise or a posttest after working inferences. The second part of the experiment conit. The experimental procedure used in the first part sisted of all subjects answering questions (called a 

may be described as a “split-group” pretest/posttest self-reporting measure) relating to their opinion on 

assessment. This means that each of the 180 partici- the validity and utility of the exercise. 

pants in the sample group was placed by random The pretest and posttest each contained 24 identidraw into either a pretest or a posttest group. Those in cal true-or-false questions about the topics included 

the pretest group took the test before working the DRI in DRI (namely noise, hearing loss and hearing protraining exercise, and those in the posttest group took tection). The assumption was that if the posttest 

the test after working DRI. The dependent variable in group’s average test score was higher than that of 

the experiment was participants’ scores on either the the pretest group, the posttest group likely gained 

some knowledge about noise, Table 1 hearing loss and hearing protection as a result of working 

the DRI exercise. If this was the 

case, it is believed that DRI is 

one reason for the information 

gain and, therefore, is an effective training exercise. 

In this type of investigation, it is important that the

test groups are equivalent. For 

research purposes, this means 

that subjects have comparable

backgrounds and work experience, as well as similar levels 

of training material content

knowledge coming into the 

experiment. If the groups are 

credibly equivalent, it can be 

argued that improved scores 

in the posttest are linked 

largely to the DRI training 

received and minimally to 

any outside effects. 
40 PROFESSIONAL SAFETY NOVEMBER 2007 www.asse.org

Self-Reporting Results 

Statement n Agree %a Disagree %b 

Table 3 Table 3 

1) This situation could happen at a drill site. 

2) The exercise will help me remember something important 

about noise and hearing loss. 

3) I learned something new from this exercise. 

4) The exercise took too long to complete. 

5) I liked working the exercise. 

6) I will use some of the ideas presented to protect my hearing. 

7) The way the material was presented is a good way for me 

to learn. 

8) The exercise was easy to read. 

179 92.2 0.6 

179 88.2 1.1 

179 73.3 6.2 

179 4.5 76.5 

179 66.5 8.4 

179 89.4 1.1 

179 89.9 2.8 

179 91.6 1.7 

Note. aAgree percentage is determined by adding together the number of 4 and 5 responses and dividing by n. bDisagree 

percentage is determined by adding together the number 1 and 2 responses and dividing by n. 

The total agree and disagree percents in the table add up to less than 100% because the percent of 3 responses is not shown. 

In other words, 100% - (agree % + disagree %) = percent of 3 responses. 

With a sufficiently large 

sample of participants (a minimum of 10 to 15 per group is a 

good rule of thumb), randomly 

assigning members can produce virtually equivalent 

groups in all respects. The 

authors claim that both groups 

in this experiment are credibly 

equivalent because 1) their 

demographics (Table 1, p. 39) 

indicate equivalency in terms 

of age and drilling experience; 2) the groups are statistically large enough; and 3) subjects were randomly placed into either group. 

Both the pretest and posttest scales consisted of 24 

true/false items. Scores on each test had a possible 

range from 0 to 24 correct. Results in an independent 

sample t test (Table 2, p. 39) showed that the mean 

posttest score (20.22) was significantly higher than 

the mean pretest score (18.87). With reference to the 

experimental design discussed earlier, this significant 

difference in scores suggests that trainees learned 

something about noise, hearing loss and hearing protection from participating in the DRI exercise. Thus, 

it can be concluded that the training exercise is 

instructionally effective, at least to some degree. 

The second part of the experiment consisted of 

participants indicating their level of agreement (on a 

scale from 1, definitely disagree, to 5, definitely 

agree) with eight statements. This self-reporting 

measure was used to assess the validity and utility 

of DRI as a training exercise. 

Statements 1, 2 and 3 report on participants’ 

assessment of the validity of DRI. As shown in Table 

3, 92.2% indicate that the “situation could happen at 

a drill site”; 88.2% agree that DRI will help them 

“remember something important about noise and 

hearing loss”; 73.3% indicated they “learned something new” from DRI. Finally, 89.4% of the participants indicate they will “use some of the ideas 

presented to protect” their hearing. The utility of the 

exercise was high as well, as almost 90% of the subjects reported “the way the material was presented is 

a good way for me to learn.” 

Paired t test 

M SD t-value p-value 

Pretest 6.13 0.998 

Posttest 7.24 0.978 9.38 < .001 

Note. n = 76. 

Table 4 Table 4 

Wearing Hearing Protection Properly 

The 3-D slide reel training aid was evaluated to 

determine whether it is effective for teaching drillers 

about the proper use of foam earplugs and earmuffs. 

A simple field experiment was conducted using a 

sample of 76 individuals. The participants were volunteers recruited from conference workshops (sponsored by the National Drilling Association and the 

National Ground Water Association) and drilling 

company training classes. 

The following experimental procedure was used: 

Participants were asked to answer eight multiplechoice questions related to using both types of hearing protection. They were then told to take as much 
www.asse.org NOVEMBER 2007 PROFESSIONAL SAFETY 41

time as needed to view and understand the information shown in all seven scenes on the 3-D slide 

reel. Next, they were instructed to review their 

answers in the multiple-choice test and change any 

they believed to be incorrect. To facilitate this, two 

sets of answer choices were placed on the multiplechoice test sheet, one set in blue (answered before 

the training) and the other set in red (answered after 

the training). It was hypothesized that their decision 

to change answers would be directly related to what 

they learned from the 3-D slide reel training aid. 

The number of correct answers recorded after 

viewing the 3-D reel (posttest) was expected to be 

greater than the number of correct answers recorded 

prior to viewing the reel (pretest). Such an outcome 

would support the belief that subjects would learn 

about the proper use of hearing protection from 

WHPP. It could then be concluded that the 3-D slide 

reel is an effective training aid. 

As shown in Table 4, subjects had more correct 

multiple-choice answers after viewing the 3-D slide 

reel (7.24) than before (6.13) and the changed score 

()) was highly significantly different from zero. It 

was concluded, therefore, that the 3-D slide training 

aid was an effective method for teaching drillers 

about wearing hearing protection properly. 

Conclusion 

Both training exercises were shown in field experiments to be effective for teaching workers in the 

drilling industry about noise and hearing protection. 

As demonstrated by the field data presented, these 

two training exercises are effective for teaching 

drillers and others who work at drill sites about the 

hazards of noise and the benefits of wearing hearing 

protection. Similar exercises developed effectively 

can help address some of the barriers to hearing conservation—worker disregard for noise as an occupational safety and health hazard; neglecting to wear 

or improperly wearing hearing protection; lack of 

knowledge concerning noise; and inadequate training. With similar training exercises developed for 

other occupational settings, hearing loss due to excessive workplace noise can be prevented. �

References 

Bauer, E.R. & Babich, D.R. (2004). Administrative controls for 

reducing worker noise exposures. In SME Annual Meeting. Preprint 04-09. Littleton, CO: Society for Mining, Metallurgy and 

Exploration Inc. 

Cole, H.P, Wiehagen, W.J., Vaught, C., et al. (2001). Use of simulation exercises for safety training in the U.S. mining industry (DHHS 

Publication No. 2001-141). Cincinnati, OH: U.S. Department of 

Health and Human Services, Centers for Disease Control and 

Prevention, NIOSH. 

Ingram, D.K. & Matetic, R.J. (2003, July). Are you operating 

an air rotary drilling rig? Is it loud? Water Well Journal, 57(7), 18-22. 

Lusk, S.L. & Kerr, M.J. (1998). Use of hearing protection and 

perceptions of noise exposure and hearing loss among construction workers. American Industrial Hygiene Association Journal, 59, 

466-470. 

Nash, J.L. (2003, Aug.). The hidden risks of OSHA’s noise 

standard. Occupational Hazards, 65, 27-33. 

National Safety Council (NSC). (2000, Feb.). Listen up! Learn 

how to protect your hearing. Today’s Supervisor. 

Walker, J. (2001). Hearing protection: Bottom-line benefit. 

Construction & Engineering Safety. 

Availability of 

Training Exercises 

“Drill Rig Incident” and “Wearing Hearing Protection Properly” 

each is available as an instructor’s copy, a practical format that 

includes additional information to help trainers or safety personnel 

implement the exercises. 

The DRI instructor’s copy contains most of the materials trainers 

will need to use the exercise. It includes suggestions for using the 

exercise, performance objectives for the training, master answer 

sheets, a scoring key, discussion notes that provide additional subject information and a summary of field test results in which the 

effectiveness of DRI was determined. The instructor’s copy also 

includes four appendices: Appendix A is the complete exercise problem booklet, which may be reproduced. Appendix B contains 

answer sheet blanks. These are furnished for employers who wish to 

have the invisible ink answers (which appear in Appendix C) printed at their location or by a local printer. Answer sheets are consumable; one is needed for each group of three to five participants who 

work the exercise together. Alternatively, an individual trainee may 

have his/her own answer sheet. Appendix D contains the 24-question pretest/posttest that was used in the field evaluation of DRI. 

The WHPP instructor’s copy contains similar information needed 

to use the 3-D slide reel for 

training. It offers practical 

suggestions on how to use 

the reel as a training aid, 

performance objectives, discussion notes that provide 

additional information to 

the user and a summary of 

field test results in which 

the effectiveness of WHPP 

was determined. The publication incudes one appendix—an eight-question 

pretest/posttest that was 

used in the field evaluation. 

“Drill Rig Incident” [DHHS 

(NIOSH) Publication No. 2005­

108] and “Wearing Hearing 

Protection Properly” [DHHS 

(NIOSH) Publication No. 2005­

107] are available, without 

charge, by contacting Bobbie 

Calhoun, NIOSH Pittsburgh 

Research Laboratory, 626 

Cochran Mill Rd., P.O. Box 

18070, Pittsburgh, PA 15236; 

(412) 386-5901; fax (412) 386­

5902; minetraining@cdc.gov.