NIOSH

Hearing Loss

Simulator

Instruction and Training Guide 

DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Centers for Disease Control and Prevention 

National Institute for Occupational Safety and Health 
 

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freely copied or reprinted. 

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DHHS (NIOSH) Publication No. 2008–119 

March 2008 

The NIOSH Hearing Loss Simulator is available for download from the Internet at this address: 

www.cdc.gov/niosh/mining/products/product47.htm 
NIOSH Hearing Loss Simulator 

Instruction and Training Guide 

Robert F. Randolph, Dana C. Reinke, Richard L. Unger 

NIOSH, Pittsburgh Research Laboratory 

Purpose 

The NIOSH Hearing Loss Simulator is a software 

training and communication tool for promoting 

hearing loss prevention. It allows a user or trainer to 

demonstrate the effects of noise exposure on 

hearing without experiencing an actual noiseinduced hearing loss. 

Estimates of the effects of different levels of noise 

exposure are based on the American National 

Standard Determination of Occupational Noise 

Exposure and Estimation of Noise-Induced Hearing 

Impairment, otherwise known as ANSI S3.44. This 

standard specifies the predicted hearing loss for 

noise-exposed populations of individuals based on 

risk factors that include gender, age, sound levels 

(in A-weighted decibels or dBA), and years of 

exposure. Algorithms specified in the standard were 

derived from empirical studies of populations that 

had no exposure to loud noise and other 

populations that had experienced various levels and 

durations of noise exposure. 

This manual explains the major objectives that can 

be addressed with the simulator and training 

scenarios that can be applied to real-life, realworker scenarios. The majority of this guide explains 

the simulator's functions in detail. Simulator users 

are encouraged to read this manual while learning 

how to run the software. 

The NIOSH Hearing Loss Simulator 

Training Objectives 

The main objective of the Hearing Loss Simulator is to 

increase motivation for taking effective hearing 

prevention action by demonstrating simulated noiseinduced hearing losses. 

The Simulator can also help teach the following facts 

about hearing loss. 

2 Hearing loss is affected by noise levels. 

2 Hearing loss worsens as the noise exposure 

duration increases. 

2 Hearing loss can become permanent. 

2 Hearing loss makes it harder to hear what others 

say. 

2 Most hearing loss is not caused by age. 

2 Speech is made up of both low and high pitch 

sounds. 

2 Hearing loss due to noise makes it harder to 

hear high pitch sounds. 

2 Hearing loss due to noise has less of an effect 

on hearing low pitch sounds. 

1 
Required and 

Recommended Items 

Computer: The Simulator runs on computers with 

Windows 98 or higher. The computer must have 

standard Windows sound support. As long as the 

computer can run current mainstream applications 

(word processing, web browser, etc.) and can play 

music, it should be more than adequate. Laptop and 

notebook computers usually work fine, but may 

need supplemental external speakers. On Windows 

Vista systems, the Simulator must be run as 

administrator in order to register its components. 

The Simulator does not run on Apple Macintosh 

computers, but users can access selected hearing 

loss simulations on the NIOSH Mining Web site. 

Speakers: External speakers that can play at 

comfortable listening volumes are necessary to hear 

the different speech types, industrial sounds, and 

musical sounds generated by the simulator. For a 

classroom setting, you should have larger amplified 

speakers that can fill the room with sound. 

Projector (optional): When training a group, a 

projector or large display will help the trainees see 

the information on the Simulator screen. The 

Simulator can be used even if the trainees can’t see 

the display because the instructor can explain the 

settings that result in the different sounds they are 

hearing. 

Headphones (optional): In conference halls and 

other settings with significant distracting 

background noise, headphones can be used to let 

trainees hear the Simulator while the background 

noise is blocked out. Full-size circumaural 

headphones that cover the ears completely are best 

at blocking background noise. An inexpensive 

headphone splitter/amplifier can be used to allow 

multiple trainees to listen through headphones at 

the same time. 

Microphone (optional): A microphone can be used to 

record custom sounds (voices, machinery, etc.) with 

the Simulator to customize it for a specific 

workplace. A good-quality external microphone that 

can connect to the computer’s microphone jack 

works best. The simple microphones built into 

notebook computers tend to have low quality and 

pick up unwanted noise from the computer itself. 

Installation 

CD-ROM: Insert the NIOSH Hearing Loss Simulator 

into your computer’s CD or DVD drive. If the installer 

does not automatically start, browse to the drive 

letter containing the installation CD and run the 

setup.exe program. 

Web: Download and run the simulator installation 

program from the NIOSH Web site: 

www.cdc.gov/niosh/mining/products/product47.htm 

Run the installer with administrator rights in 

Windows 2000, XP, or Vista. 

For both versions, follow the onscreen prompts. When complete, the 

program can be run from an icon in 

your Start menu or (optionally) on the 

desktop. 

In Windows Vista, the program must be run as 

Administrator. 

2 

HLSim icon 
 

Guide to All Features 

This section describes all of the Simulator’s 

functions available through its screens and menus. 

Main Screen 

When the program is first started, this main screen 

showing the basic functions is displayed. From here 

you can use tabs below the menu bar to select other 

screens to change or record sounds played by the 

program. 

Adjust the volume on your computer so the spoken 

message is at a comfortable listening level that’s 

audible to every listener. 

Then select Exposure Predicted from the Hearing 

Loss list. 

Main Screen with Exposure 

Selecting the Exposure Predicted option changes 

the main screen by adding controls to adjust the 

amount of noise exposure being simulated. 

In the sample screen shown here, the default 

exposure settings have been selected, and sound 

playback has started. 

Quick start tip: Click on the top menu to 

start sounds playing. 

Toolbar 

The toolbar appears at the top of all screens. 

Exit - Exits the program. 

Start/Stop Toggle - Controls the playback of the 

speech and noise sources. The F2 key also 

performs this function. 

3 About - Information about the Hearing Loss 

Simulator (version number, technical support, 

etc.). 

1 

2 

4 

5 

6 

Help - Displays HLSim help, documentation, and 

sample scenarios. 

NIOSH Mining Web - Opens the default browser 

to the NIOSH Mining Web site. 

Pause - Pauses playback of the sound file. The 

F3 key also performs this function. 

3 
Graphical Display 

This graphical display shows current instantaneous 

levels of sound across the frequency spectrum. This 

is useful for showing the amounts of low- and highfrequency sound in the recording. For instance, for 

the female voice the high-frequency bars toward the 

right side of the graph will show higher peak levels 

than the male voice. 

The display also demonstrates the loss of highfrequency information when a noise-induced 

hearing loss is simulated. 

Hearing Loss choices 

This panel is used to select how the program 

simulates a hearing loss. 

No Loss - Removes all hearing loss. 

Exposure Predicted - High noise exposures cause 

much more hearing damage than lower exposures. 

This option applies the effect of different levels of 

noise exposure combined with age, gender, and 

other variables. When this option is selected, the 

main screen expands to show additional exposure 

controls. 

Mild Generic - Applies a “mild” level of noiseinduced hearing loss: 20 dB hearing level at 4000 

Hz with surrounding frequencies impaired to a 

lesser extent. 

Moderate Generic - Applies a “moderate” level of 

noise-induced hearing loss: 30 dB hearing level at 

4000 Hz with surrounding frequencies impaired to a 

lesser extent. 

Mod/Severe Generic - Applies a “moderate to 

severe” level of noise-induced hearing loss: 40 dB 

hearing level at 4000Hz with surrounding 

frequencies impaired to a lesser extent. 

Manual - Activates the frequency band sliders so 

you can apply a hearing loss manually. 

Compensate for Loss - Once a loss is simulated, it 

can be “compensated” for. This has the effect of 

4 

boosting the sound by an amount equivalent to the 

loss. To an imperfect extent, the boosted playback 

can compensate for a hearing loss to give trainees 

an idea of what it would be like to regain their 

normal hearing. 

The limitations of any mechanical playback system 

and the complexity of the auditory system make it 

impossible to exactly reverse a hearing loss. Also, in 

cases of severe hearing loss, boosting the sound 

enough to compensate for a large deficiency and 

playing the resulting sounds through a high-power 

loudspeaker or headphone system could potentially 

generate very loud and unpleasant sound levels. In 

extreme cases, the levels could even become 

hazardous, so use this feature with caution — turn 

the volume down first and bring it up gradually. 
Frequency Band Sliders 

These 10 sliders control different frequency bands. 

When the program is simulating a predicted hearing 

loss, these sliders are automatically adjusted to 

reflect a predicted hearing level as a result of noise 

exposure. 

When you set the Hearing Loss to “Manual” you can 

manipulate the sliders directly. You might do this to 

enter the results of an actual audiogram. Then, 

others who have no hearing loss could, in effect, 

hear an approximation of the person’s hearing 

whose test results were entered. This is only an 

approximation. Individuals with sensori-neural 

hearing loss often have altered loudness perception 

and other subjective effects that are difficult to 

simulate accurately. 

Also, since each slider can be manipulated 

independently, you can pinpoint the effects of 

hearing loss in each frequency band. For instance, a 

warning beeper may become much less audible as 

a result of a loss in a single frequency band. 

Hearing Loss Status 

This portion of the screen contains information 

about status of the Simulator, including current 

hearing loss settings. 

5 
 

Exposure Predicted Loss 

Parameters 

1 Include Age Effects - When checked, the
 

effects of age are included in the hearing loss 

calculation. This provides a convenient way to 

demonstrate the effect that noise alone has on 

hearing loss, apart from aging. 

2 Gender - Males tend to have higher levels of 

hearing loss than females who have had the same 

noise exposure, so the program allows the user to 

specify the simulated worker’s sex. 

3 Age - Some hearing loss occurs as people age, 

but deafness or even a severe hearing loss is not 

inevitable. One of the major lessons to be learned 

from the Simulator is that aging usually causes 

much less hearing loss than does noise exposure. 

The simulated individual’s age in years can be 

entered to show how older people tend to have a 

gradual loss in the high frequencies, i.e., an older 

worker who has not been exposed to loud noise 

will typically have worse hearing at 8000 Hz than 

at any lower frequency. On the other hand, a 

worker exposed to large amounts of noise will 

typically have a “notch” in their hearing sensitivity 

around 4000 Hz or 6000 Hz, and will have better 

hearing at 8000 Hz. 

4 Include Effects of Noise Exposure - When 

checked, the effects of Years of Exposure, 

exposure level and fractile are included in the 

hearing loss calculation. This provides a 

convenient way to demonstrate the effect that age 

only has on hearing loss. 

5 Years of Exposure - Time is the second major 

ingredient of exposure. This is set in years to 

represent a noisy period in the simulated 

individual’s life. It can cover just a noisy portion of 

a career (e.g., 10 years of working in a mill) or 

multiple noisy periods. The years represent 

working days, not continuous exposure. This value 

should be kept to the 0–40 year range for 

predictions supported by the data behind the ANSI 

S3.44 standard. 

6 Exposure Level (dBA) - As expected, highintensity sound levels cause much more hearing 

damage than lower levels. The effect of different 

levels of noise can be simulated by entering the 

desired A-weighted sound level in decibels. The Aweighting scale is used for all the key sound 

pressure level measurement standards in the Mine 

Safety and Health Administration (MSHA) and 

Occupational Safety and Health Administration 

(OSHA) regulations, so it should be familiar to both 

trainers and trainees. This value should be kept to 

the 75–100 dBA range for predictions supported by 

the data behind the ANSI S3.44 standard. 

For simplicity, a single dBA number is set in the 

simulator, although employees may correctly point 

out that the sound levels they are exposed to vary 

considerably over time. Because of this, the dBA 

value should represent an estimate of the average 

6 
exposure over the simulated time period, commonly 

referred to as the “time-weighted average” (TWA). 

7 Fractile (population distribution) - Noise does not 

affect everyone to the same extent. To account for 

variations within the population, the ANSI S3.44 

standard specifies expected hearing loss for 

different population fractiles. 

The program allows the user to specify the 0.1, 

0.25, 0.5, 0.75, and 0.9 fractiles. For instance, a 

worker at the 0.1 fractile would have more hearing 

loss than 90% of the equally exposed population. 

Set Speech and Noise Source 

This screen is reached by selecting the tab for “Set 

Speech and Noise Source.” You can return to the 

main screen at any time by selecting the “Main” tab. 

1 Speech Source (foreground sound) - Human 

speech is provided as both the most complex and 

important foreground sound most workers need to 

perceive. You can choose either a male or female 

voice recording from the dropdown list. 

2 Noise Source (background sound) - Background 

sounds often severely tax a listener’s ability to hear 

and/or comprehend the intended message. The 

simulator allows the choice of several types of 

background sounds, including some recorded 

worksite sounds (continuous miner, haulage 

machine, drill) and some more generic standard 

background noises (male or female “speech 

babble,” white noise, etc.). 

3 Browse for a Sound File - Select a Windows WAV 

file for playback in place of one of the sounds in the 

dropdown list. 

4 Stop Playback - Stop the playback of the sound 

file. 

7 

Those at the 0.75 fractile would have more hearing 

loss than just 25% of the population. 

By changing this control to the low (0.1 or 0.25) 

settings, a trainer can show that lower exposure 

levels can still be dangerous for some workers, even 

if they are relatively “safe” for the average worker. 

Since most workers do not have a way of knowing 

their individual susceptibility, this allows them to err 

on the side of caution. 

8 Default Values - Sets all the exposure predicted 

variables to their default values. 

5 Loop - Makes the sound repeat indefinitely. 

6 Speech to Noise Ratio - The Speech to Noise 

Ratio control affects the loudness of the 

background noise source relative to the foreground 

sound. Use this to demonstrate how increasing 

background noise interferes more with 

understanding the foreground speech recording. 

7 Set to 1.0 - Resets the Speech to Noise Ratio to 

the default value of 1.0. 
Record Screen 

This screen is reached by selecting the “Record” 

tab. You can return to the main screen at any time 

by selecting the “Main” tab. 

1 Recording Level - Displays the input sound level 

while making a recording. Adjust the computer’s 

input controls so that the loudest peak levels stay 

below the red area to the right. 

2 Record - Click this button to start recording a 

standard Windows WAV sound file for use as either 

foreground or background source. This can be used 

to record a different foreground voice message 

customized for trainees or to record a special 

machine or warning signal that's common at the 

trainees' worksite. 

The program will ask for a file name before saving 

the recording. This feature requires a microphone or 

other sound source attached to the PC sound input. 

8 

Training Scenarios 

The Simulator can be used to show “real-worker, 

real-life” scenarios. A good training plan using the 

Simulator would work through a series of scenarios, 

using trainee input to tailor the lesson to the 

audience. Some of the many possible scenarios are 

listed. 

Older worker, noise-exposed 

This scenario is one of the most important ones to 

include in a training session, especially with younger 

workers. A hypothetical male or female older 

worker, perhaps nearing retirement, would be 

described. He or she should be characterized as in 

the range of 55–65 years old with 35–45 years of 

exposure to 90–100 dBA. Users can select age and 

experience numbers that are typical of their 

workplace or industry. The trainer can then 

demonstrate the significant hearing loss this worker 

will have going into retirement. 
Older worker, no exposure 

Immediately following a demonstration about a 

hypothetical noise-exposed older worker, the trainer 

can set the exposure years to zero and simulate an 

equivalent worker with no exposure. This will serve 

to counter any assumption that the first worker’s 

hearing loss was a natural consequence of aging. 

Instead, trainees will see that a relatively small 

amount of high-frequency loss is expected in older 

workers, but that noise exposure is responsible for 

much more of the damage. 

Midcareer worker 

Especially if there are a large number of midcareer 

trainees, a worker with 10–20 years of exposure 

may be simulated. Based on this worker, several 

progressions can be followed. For instance, 

additional exposure years can be added to show the 

accumulation of more hearing loss. It also allows 

comparison with an older non-noise-exposed 

worker, which then allows the trainer to make the 

point that, with enough exposure, a 30-year-old 

worker may have, in effect, 50-year-old ears. 

Individualized 

The simulator can also be used as an individualized 

training and counseling tool. For instance, the 

trainer can show a worker how his/her hearing test 

results can be entered directly into the Simulator 

using the frequency band sliders in manual mode. 

The trainer can then drag the sliders down to show 

the additional loss that would occur after further 

noise exposure. A rough estimate of how much 

additional loss to add could be obtained through an 

exposure-predicted loss for 5–10 years of future 

exposure. 

For More Information 

For more information on ANSI standard S3.44: 

American National Standards Institute 

www.ansi.org. 

Criteria for a Recommended Standard. 

Occupational Noise Exposure. June 1998. Centers 

for Disease Control and Prevention. NIOSH. 

www.cdc.gov/niosh/docs/98-126. 

Preventing Occupational Hearing Loss: A Practical 

Guide. June 1996. edited by John R. Franks, Mark 

R. Stephenson, Carol J. Merry. Centers for Disease 

Control and Prevention. NIOSH: 

www.cdc.gov/niosh/96-110.html. 

Downloading Information 

The NIOSH Hearing Loss Simulator is available for 

download from the Internet at this address: 

www.cdc.gov/niosh/mining/products/product47.htm 

9 
 

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safety and health at work for all people 

through research and prevention 

To receive NIOSH documents or more information about occupational safety and health 

topics, contact NIOSH at 

1–800–CDC–INFO (1–800–232–4636) 

TTY: 1–888–232–6348 

e-mail: cdcinfo@cdc.gov 

or visit the NIOSH Web site at www.cdc.gov/niosh. 

For a monthly update on news at NIOSH, subscribe to NIOSH eNews by visiting 

www.cdc.gov/niosh/eNews. 

DHHS (NIOSH) Publication No. 2008–119