Auditory Demonstrations for Science, Technology, 

Engineering, and Mathematics (STEM) Outreach

by Ashley N Foots, Jeremy R Gaston, Kimberly A Pollard, and 

Timothy J Mermagen

ARL-SR-0306 January 2015

Approved for public release; distribution is unlimited.
NOTICES

Disclaimers

The findings in this report are not to be construed as an official Department of the Army position unless 

so designated by other authorized documents.

Citation of manufacturer’s or trade names does not constitute an official endorsement or approval of the 

use thereof.

Destroy this report when it is no longer needed. Do not return it to the originator.
Army Research Laboratory

Aberdeen Proving Ground, MD 21005-5425

ARL-SR-0306 January 2015

Auditory Demonstrations for Science, Technology, 

Engineering, and Mathematics (STEM) Outreach

Ashley N Foots, Jeremy R Gaston, Kimberly A Pollard, and 

Timothy J Mermagen

Human Research and Engineering Directorate, ARL

Approved for public release; distribution is unlimited.
ii

REPORT DOCUMENTATION PAGE Form Approved

OMB No. 0704-0188

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering 

and maintaining the data needed, and completing and reviewing the collection information. Send comments regarding this burden estimate or any other aspect of this collection of information, 

including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson 

Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to 

comply with a collection of information if it does not display a currently valid OMB control number.

PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS.

1. REPORT DATE (DD-MM-YYYY)

January 2015

2. REPORT TYPE

Final

3. DATES COVERED (From - To)

June 2014–August 2014

4. TITLE AND SUBTITLE

Auditory Demonstrations for Science, Technology, Engineering, and Mathematics 

(STEM) Outreach

5a. CONTRACT NUMBER

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

Ashley N Foots, Jeremy R Gaston, Kimberly A Pollard, and Timothy J Mermagen

5d. PROJECT NUMBER

5e. TASK NUMBER

5f. WORK UNIT NUMBER

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

US Army Research Laboratory

ATTN: RDRL-HRS-D

Aberdeen Proving Ground, MD 21005-5425

8. PERFORMING ORGANIZATION

 REPORT NUMBER

ARL-SR-0306

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S)

11. SPONSOR/MONITOR'S REPORT

 NUMBER(S)

12. DISTRIBUTION/AVAILABILITY STATEMENT

Approved for public release; distribution is unlimited.

13. SUPPLEMENTARY NOTES

14. ABSTRACT

The US Army Research Laboratory (ARL) participates in science, technology, engineering, and mathematics (STEM) outreach 

programs, including the Gains in the Education of Mathematics and Science (GEMS) program under the Army Educational 

Outreach Program. During GEMS, ARL provides STEM instruction and lab demonstrations to visiting groups of students 

ranging from fifth graders through high school graduates. This report documents the involvement of ARL’s Human Research 

and Engineering Directorate’s Perceptual Sciences Branch (PSB) in the 2014 GEMS program and provides detailed 

descriptions of lecture materials, slides, and hands-on demonstrations that were used. PSB provided education through lecture 

and demonstrations on 3 auditory topics: 1) the anatomy and physiology of hearing and hearing conservation, 2) acoustic 

resonance, and 3) bone conduction. Students learned about how the ear works, what listening levels are safe, how objects such 

as musical instruments or the vocal tract resonate with sound, how sound can travel through bones, and when bone-conducted 

hearing is used. Demonstrations included measuring earbud output levels on an acoustic test fixture, visualizing resonance 

nodes with a Chladni plate, and listening to sounds through bone conduction headsets. 

15. SUBJECT TERMS

STEM outreach, auditory demonstrations, Gains in the Education of Mathematics and Science, hearing conservation, bone 

conduction, acoustic resonance

16. SECURITY CLASSIFICATION OF: 

17. LIMITATION

OF ABSTRACT

UU

18. NUMBER

OF PAGES

46

19a. NAME OF RESPONSIBLE PERSON

Ashley N Foots

a. REPORT

Unclassified

b. ABSTRACT

Unclassified

c. THIS PAGE

Unclassified

19b. TELEPHONE NUMBER (Include area code)

410-278-5853

Standard Form 298 (Rev. 8/98)

Prescribed by ANSI Std. Z39.18
iii

Contents

List of Figures iv

Acknowledgments v

1. Introduction 1

2. Researchers and Responsibilities 2

3. Learning Topics 2

3.1 Topic 1: Anatomy of Hearing and Hearing Conservation ..............................................2

3.1.1 Lecture Background ............................................................................................3

3.1.2 Interactive Topic Station: Preferred Listening Levels for Music........................7

3.1.3 Demonstration Equipment Setup.........................................................................8

3.1.4 Demonstration Procedure ..................................................................................10

3.2 Topic 2: Acoustic Resonance ........................................................................................11

3.2.1 Lecture Background ..........................................................................................11

3.2.2 Interactive Topic Station: Chladni Plate ...........................................................12

3.2.3 Demonstration Equipment Setup.......................................................................13

3.2.4 Demonstration Procedure ..................................................................................14

3.3 Topic 3: Bone Conduction ............................................................................................15

3.3.1 Lecture Background ..........................................................................................15

3.3.2 Interactive Topic Station: Bone Conduction Hearing .......................................17

3.3.3 Demonstration Equipment Setup.......................................................................18

3.3.4 Demonstration Procedure ..................................................................................19

4. Conclusion 20

5. References 21

Appendix. Environment for Auditory Research (EAR) Presentation 23

List of Symbols, Abbreviations, and Acronyms 35

Distribution List 36
iv

List of Figures

Fig. 1 Anatomy of human ear. (Permission to reprint given by Dangerous Decibels on 

September 10, 2014. Image retrieved from http://www 

.dangerousdecibels.org/education/information-center/how-we-hear/.) .....................................3

Fig. 2 Normal hair cells (left) and damaged hair cells (right). (Permission to reprint given by 

Dangerous Decibels on September 10, 2014. Image retrieved from 

http://www.dangerousdecibels.org /education/information-center/.) ........................................4

Fig. 3 Noise thermometer. (Permission to reprint given by Dangerous Decibels on 

September 10, 2014. Image retrieved from 

http://www.dangerousdecibels.org/education/information-center/decibel-exposure-time

-guidelines/.) ..............................................................................................................................5

Fig. 4 Recommended permissible exposure time from NIOSH. (Permission to reprint given 

by Dangerous Decibels on September 10, 2014. Image retrieved from 

http://www.dangerousdecibels.org/education/information-center/decibel-exposure-time

-guidelines/.) ..............................................................................................................................6

Fig. 5 ARL photo of examples of hearing protection devices including 1) Peltor supra-aural 

hearing protection, model MT15H68FB-03, 2) Peltor Tactical 6-S supra-aural hearing 

protection, 3) Gunfenders, 4) Ear Ultrafit, 5) Ear Classic foam earplugs, 6) Tasco Tri-fit, 

7) Combat Arms Earplugs generation 2, and 8) Moldex Pura-fit 6800.....................................7

Fig. 6 ARL photo of G.R.A.S. 26AC microphones mounted internally to 2 G.R.A.S. 711 

acoustic couplers that mimic the resonances of the human ear canal........................................8

Fig. 7 ARL photo of KEMAR’s realistic pinna.............................................................................9

Fig. 8 ARL photo of portable media player station .......................................................................9

Fig. 9 Vibration patterns on the back of the guitar body as a function of driving frequency. 

(Image retrieved from http://en.wikipedia.org/wiki/Ernst_Chladni#mediaviewer

/File:Chladni_guitar.svg.) ........................................................................................................12

Fig. 10 ARL photo of Chladni plate station setup including 1) function generator, 2) audio 

amplifier, and 3) plate and loudspeaker assembly. ..................................................................13

Fig. 11 ARL photo of Chladni Plate patterns ..............................................................................14

Fig. 12 A bone-anchored hearing aid, a bone conduction device. (Image retrieved from 

http://commons.wikimedia.org/wiki/File:BAHA_sound_processing_device

_in_place.jpg.)..........................................................................................................................16

Fig. 13 ARL photo of a Soldier wearing a bone conduction communication headset. The 

ears are left unoccluded to maximize situation awareness. .....................................................17

Fig. 14 ARL photo of the bone conduction station including 1) full-face respirator with 

Huari HRE-5673 system, 2) Samson C-que 8-headphone amplifier, 3) iPod, 4) Finis 

SwiMP3, 5) Goldendance Double Bone, 6) Temco HG-17, 7) Radioear B70A bone 

vibrators, 8) Aftershokz Sport headset, 9) Amphicom Aqua FM, and 10) tuning forks. ........18
v

Acknowledgments

We would like to thank and acknowledge several people for their support and assistance during 

the Gains in the Education of Mathematics and Science (GEMS) program. First, we would like 

to thank Dr Paula Henry for helping develop the initial demonstration materials. Dr Henry has 

worked with GEMS students in the past and used similar materials when she was an instructor 

with the program. We would like to thank Dr Kelly Dickerson for serving as an assistant 

instructor at the portable media player station. Dr Dickerson also provided administrative support 

during the PowerPoint presentations. We would like to thank Mr Miller Roberts for serving as an 

assistant instructor at the resonance station. Mr Roberts also assisted in the setup of the 

demonstration materials. Finally, we would like to thank Ms Luci Salvi for working with the 

GEMS outreach program and coordinating with the Human Research and Engineering 

Directorate’s branches. 
vi

INTENTIONALLY LEFT BLANK.
1

1. Introduction

The US Army Research Laboratory (ARL) participates in an outreach program called Gains in 

the Education of Mathematics and Science (GEMS), which is under the Army Educational 

Outreach Program. The objective of GEMS is to support students with education in areas of 

science, engineering, mathematics, computational sciences, computation biology, biomedical 

sciences, chemistry, and biology. GEMS students range in age from rising fifth graders to high 

school graduates. The students visit ARL facilities and engage in hands-on learning in the 

laboratory. The students are exposed to many aspects and applications of mathematics and 

science that they would not typically have the opportunity to learn about in school. GEMS 

sessions are week-long programs where students visit different labs on different days. At the end 

of the week, students present a PowerPoint presentation on one of the topics that they learned 

about during the week. In 2014, ARL’s Human Research and Engineering Directorate (HRED) 

hosted one of these lab days biweekly for 8 weeks.

ARL/HRED’s Perceptual Sciences Branch (PSB) provided GEMS student learning experiences 

in 3 topic areas: 1) anatomy and physiology of hearing with a special focus on hearing 

conservation, 2) acoustic resonance, and 3) bone conduction hearing. There were 3 groups of 

students each week, and each group was provided with approximately 1 h of instruction. The 1-h 

session was divided into 2 main parts. The initial part consisted of a PowerPoint presentation 

introducing all of the background information for the 3 topics (PowerPoint slides and student 

worksheets are included in the Appendix). In the second part, students were organized into 3

groups to rotate through the interactive stations related to each topic. The 3 stations included 

1) a preferred listening level station, 2) a Chladni plate station, and 3) a bone conduction station. 

Hands-on, interactive demonstrations were provided at each of the stations. The students 

received handouts that included the PowerPoint presentation and worksheets for each station so 

they could fill in information about the demonstrations. The purpose of the worksheets was to 

allow students to write down notes about their experiences and keep the students engaged in the 

activities. Additionally, ARL requires GEMS students to complete a presentation at the end of 

the GEMS week, and the handouts and worksheets also help students take notes for their 

presentation. The presentation is 1 or 2 slides summarizing one of the topics that the students 

participated in during the week. The students are assigned a specific topic by GEMs coordinators 

so that all students do not present on the same topics. Descriptions and procedures followed at 

each station are provided in subsequent sections, including the information told to the students

by the instructors.
2

In designing the learning topics, the goal was to create lecture and demonstration materials 

suitable for all ages within the GEMS program. Also, it was important to make the complex 

scientific topics relatable and understandable to an audience that has limited or no background 

knowledge of the topic areas. Each presenter was encouraged to give background information on 

their education and current positions to inspire students to become interested and learn more 

about careers in mathematics and science. Previous GEMS students have gone on to work with 

ARL as interns through college and graduate school. In addition, some are now employed by 

ARL. 

2. Researchers and Responsibilities

Ashley Foots conducted the presentation on the anatomy of hearing and hearing conservation. 

She also assisted at the preferred listening level station to help students calculate and discuss 

recommended exposure times based on their preferred listening level for music. Jeremy Gaston 

presented the topic on acoustic resonance and was the instructor at the preferred listening level 

station. Kimberly Pollard presented the topic on bone conduction and was the instructor at the 

bone conduction station. Tim Mermagen helped develop the instruction materials and equipment

used for the listening level station and the Chladni plate station, and he was the instructor at the 

Chladni plate station. Miller Roberts assisted Tim Mermagen in the equipment setup and was the 

assistant instructor at the Chladni plate station. Finally, Kelly Dickerson served as an assistant 

instructor at the preferred listening level station. 

3. Learning Topics

The leaning topics are organized into several sections. First, a general overview is given 

followed by the lecture background section. The majority of the lecture background section is in 

present tense because it represents information as the lecturer presented it to the students. In 

addition, this information has been indented to differentiate it from background and procedural 

details important to the reader. The lecture background information is followed by a description 

of materials and procedures important to the associated interactive topic station. Again, relevant 

information presented to the students by the lecturers has been indented to differentiate it from 

procedural details.

3.1 Topic 1: Anatomy of Hearing and Hearing Conservation 

The topic on anatomy and physiology of hearing included overviews of the auditory pathway, 

hearing conservation, and the types and use of hearing protection devices. The related interactive 

topic station was an activity that allowed students to adjust the sound level of music to their 
3

preferred listening level using a portable media player. The preferred listening level was then 

compared to the recommended exposure limits discussed in the lecture. 

3.1.1 Lecture Background 

The following information was presented to the students by the lecturer to provide background 

information about the topic: 

Sound waves travel down the ear canal and vibrate the eardrum [Gelfand 2009]. Once the 

eardrum is vibrated, it sets the ossicular chain in motion. The ossicular chain consists of 3 small 

bones in the middle ear: the malleus (hammer), incus (anvil), and stapes (stirrup). The foot plate 

of the stapes then presses on the oval window of the cochlea causing the fluid in the cochlea to 

move. The fluid in the cochlea creates tension differences which cause the fine structures of the 

hair cells in the cochlea to move. The hair cells for high frequencies are closest to the base of the 

cochlea and the hair cells for low frequencies are closest to the apex of the cochlea. Mechanical 

energy is transformed into electrical signals that are then sent to the brain. The brain then 

recognizes the signal as speech, music, etc. An anatomical diagram of the auditory system can be 

seen in Fig. 1. Now I am going to show you a short video that shows how a sound moves through 

the auditory pathway. 

Fig. 1 Anatomy of human ear. (Permission to reprint given by Dangerous 

Decibels on September 10, 2014. Image retrieved from http://www

.dangerousdecibels.org/education/information-center/how-we-hear/.)

Students were then shown a short video that gave an excellent description of the auditory 

pathway (http://www.youtube.com/watch?v=flIAxGsV1q0), followed by a second video that 

demonstrated how individual hair cells work (http://auditoryneuroscience.com/ear/dancing

_hair_cell).
4

A second video demonstrates how individual hair cells work. This video is of an individual outer 

hair cell from a guinea pig. An electrode was attached to the hair cell and researchers used an 

alternating current (“Rock Around the Clock” by Bill Haley and His Comets) to stimulate the hair 

cell. The hair cell in the video was observed under a microscope and recorded. Typically, normal 

healthy hair cells are straight and stand tall [Fig. 2] whereas damaged hair cells are unable to 

stand straight up and down, appearing to be bent. There are 3 types of hearing loss including 

sensorineural, conductive, and mixed hearing loss. Damage to the hair cells is a cause of 

sensorineural hearing loss. Hair cells cannot be regenerated, so this damage is permanent. 

Conductive hearing loss occurs when there is damage or obstruction in the outer or middle ear 

preventing sound from reaching the inner ear effectively. This can be temporary due to fluid in 

the middle ear or earwax buildup in the ear canal, but it can also be permanent. A mixed hearing 

loss is a combination of sensorineural hearing loss and conductive hearing loss. Hearing loss can 

range in severity from mild to total hearing loss. 

Fig. 2 Normal hair cells (left) and damaged hair cells (right). 

(Permission to reprint given by Dangerous Decibels on 

September 10, 2014. Image retrieved from 

http://www.dangerousdecibels.org 

/education/information-center/.)

Repeated or extended durations of exposure to loud sounds can cause hair cell damage and result 

in hearing loss. There are many situations and types of loud sounds to which individuals in 

modern society are typically exposed to. 

Students were then provided with a “Noise Thermometer” bookmark.

This bookmark is a visual representation of various common sounds that range from soft to very 

loud, with the corresponding intensity level marked [Fig. 3]. Common sounds can be compared to 

the recommended exposure time from the National Institute for Occupational Safety and Health 

(NIOSH) to raise awareness of the risk of hearing damage resulting from exposure to the sounds. 

For instance, a leaf blower is approximately 110–115 dB. To prevent hearing damage, one should 

not be exposed to 115 dB for more than 30 s without hearing protection. Most people do not 

know how loud a leaf blower can be nor do they realize the damage that can occur to their 

hearing. The leaf blower is one of many examples. The recommended exposure times from 

NIOSH can be viewed in Fig. 4. 
5

Fig. 3 Noise thermometer. (Permission to reprint 

given by Dangerous Decibels on September 

10, 2014. Image retrieved from 

http://www.dangerousdecibels.org

/education/information-center/decibel

-exposure-time-guidelines/.)
6

Fig. 4 Recommended permissible exposure time from NIOSH. (Permission to reprint given by 

Dangerous Decibels on September 10, 2014. Image retrieved from 

http://www.dangerousdecibels.org/education/information-center/decibel-exposure-time

-guidelines/.)

Auditory hair cells do not regenerate, so by the time the damage occurs the hearing loss will be 

permanent. Thus, it is important to prevent hearing damage by reducing the intensity of sounds 

entering the auditory pathway. Hearing protection attenuates environmental sounds by reflecting 

or absorbing some portion of the sound waves. There are 2 types of hearing protection, over the 

ear and in the ear. A display of hearing protection can be seen in Fig. 5. The over-the-ear style 

hearing protection devices cover the entire outer ear. Over-the-ear style hearing protection 

devices are being used properly when the entire ear is covered by the muff and the muff creates a 

seal. The in-the-ear style hearing protection devices slide into the ear canal and expand. The inthe-ear style hearing protection is often more difficult to insert properly, which reduces the 

effectiveness. It helps to lift up on the pinna, straightening the ear canal, while inserting the 

compressed plug. If hearing protection is not available, then sounds should be turned down at the 

source. If turning loud sounds down is not an option, then walking away from the loud sound 

should be considered. Additional information on hearing conservation can be found at 

http://www.dangerousdecibels.org/.
7

Fig. 5 ARL photo of examples of hearing protection devices including 1) Peltor supra-aural hearing protection, 

model MT15H68FB-03, 2) Peltor Tactical 6-S supra-aural hearing protection, 3) Gunfenders, 4) Ear 

Ultrafit, 5) Ear Classic foam earplugs, 6) Tasco Tri-fit, 7) Combat Arms Earplugs generation 2, and 

8) Moldex Pura-fit 6800.

3.1.2 Interactive Topic Station: Preferred Listening Levels for Music

The purpose of this interactive station was to measure the potentially dangerous listening habits 

of students and provide information on how to protect hearing. The students adjusted a portable 

media player with earbuds to their preferred listening level. The students then compared their 

exposure level to the NIOSH-recommended sound exposure times (NIOSH 1998) for how long 

they could listen to sounds at that level without potentially causing permanent hearing damage. 

After the measurement of preferred listening levels and permissible sound exposure times, 

instructors provided students with strategies to protect their hearing while listening to music. For 

example, sound attenuating circumaural headphones or in-the-ear-canal phones can be used to 

reduce background noise, and reducing background noise can lead to lower preferred listening 

levels (Henry and Foots 2012). 
8

3.1.3 Demonstration Equipment Setup 

A portable media player was used to play a song through common earbud headphones. The 

selection of the song was a challenge because the song needed to be age appropriate. The song 

selected was “Happy” by Pharell Williams. Sound levels were measured using a Knowles 

Electronic Manikin for Acoustic Research (KEMAR). KEMAR is an acoustic test fixture that 

has 2 G.R.A.S. 26AC microphones mounted internally to 2 G.R.A.S. 711 acoustic couplers that 

mimic the resonances of the human ear canal (Fig. 6). Realistic pinnae, mounted to the outside of 

KEMAR, held the earbuds much like the human ear does (Fig. 7). The KEMAR microphones 

were powered by a G.R.A.S. 12AK power supply, and sound-level data were analyzed using a 

commercial audio program running on a laptop personal computer (PC). Calibration of the 

KEMAR microphones was accomplished by recording a signal through the KEMAR from a 

G.R.A.S. 42 AA pistonphone calibrator, which produces a 250-Hz tone at 114-dB SPL. The 

equipment setup can be seen in Fig. 8.

Fig. 6 ARL photo of G.R.A.S. 26AC microphones 

mounted internally to 2 G.R.A.S. 711 acoustic 

couplers that mimic the resonances of the human 

ear canal
9

Fig. 7 ARL photo of KEMAR’s realistic pinna

Fig. 8 ARL photo of portable media player station
10

3.1.4 Demonstration Procedure

Each student was first handed a new set of earbud headphones for use during the activity. 

Instructors then began by briefly describing KEMAR:

KEMAR is an auditory test fixture that is used for making sound measurements, which can give 

researchers a good idea of what a sound may be like at the human ear. This is because KEMAR 

has a realistic pinna and realistic ear canal that mimic the resonances of the real human ear canal. 

These features alter the incoming sounds similar to the human ear before being recorded by the 

microphones. 

The microphones in KEMAR’s ear canals convert the sound waves that hit the microphone 

diaphragm into electrical voltage. All of the components of the recording chain from the KEMAR 

microphones to the laptop PC represent an electrical system, and each part affects the intensity of 

the signal. The sound meters displayed on the laptop PC show the maximum possible level as 

zero, and lower levels are all negative from zero to negative infinity. The value of zero represents 

the maximum voltage value that can be measured by the system, and all measurements are 

relative to this maximum value. To convert the “relative” values to absolute measurements, 

calibration is completed by playing a known signal through the system and noting the relative 

value for that signal. This is accomplished by playing a signal produced by a sound calibrator 

through the system. The signal used was a 250-Hz tone at a sound pressure level of 114 dB. This 

known signal was used to reference all of the measurements. The sound meters will show that the 

calibration signal produces a relative value of –6 dB. This means that there is 6 dB of sound 

“headroom” before a signal would exceed the electrical maximum of the system. To compute the 

calibration offset value (CVoffset), the measured value (relative level [RL] on the computer) needs 

to be subtracted from the real value of the calibration signal. 

Calibration signal level = CVoffset + RL

CVoffset = Calibration signal level – RL

The actual listening level (LL) of any sound can then be calculated by adding the measured level 

(RL) of a played sound to the CVoffset: 

LL = CVoffset + RL

Students made these calculations on a provided worksheet (see Appendix, Portable Media Player 

Worksheet). When a student calculated their LL, they looked at the sound thermometer described 

in the lecture to obtain the permissible exposure time for their individual LL based on NIOSH 

recommendations (NIOSH 1998). Finally, the instructors discussed with students the importance 

of protecting their hearing and gave suggestions about ways to help limit exposure to loud music. 

For example, using hearing protectors or moving farther away (i.e., 6-dB-drop in sound level per 

doubling of distance) at concerts was discussed. When listening to portable music players, use of 
11

circumaural (over the ear), closed (sound attenuating) headphones can help reduce background 

sounds. This is also true of in-the-ear-canal phones, which can significantly attenuate 

background noise. 

3.2 Topic 2: Acoustic Resonance

The topic on resonance included a discussion of acoustic resonance and examples of how 

changing the size, shape, and driving frequency of a sound source can result in changes in the 

resonant frequency. After the lecture, students participated in a hands-on activity using a Chladni 

plate to demonstrate the concept of resonance. 

3.2.1 Lecture Background 

The following information was presented to the students by the lecturer to provide background 

information about the topic: 

When objects vibrate, the frequency at which the maximum movement occurs is called its natural 

or resonant frequency. Two primary ways to change the resonant frequency of an object are to 1) 

change the size or shape of the object, or 2) change the driving frequency at which the object 

vibrates [for a speech example see Denes and Pinson 1993; for a musical instrument example see 

Howard and Angus 2009]. 

One simple example of how size and shape can affect the resonant frequency is a vibrating wine 

glass; when the volume of air changes, so does the resonant frequency. This can be easily 

demonstrated by running your finger along the top of a wine glass to provide the vibration source. 

The frequency at which the glass resonates is related to the volume of air in the glass. To change 

the resonant frequency, one simply needs to add or remove liquid in the glass to change the 

volume of air. A more complicated example is the human vocal tract. In the human vocal tract 

there are many moving parts that serve to rapidly change the size and shape of the tract. In 

addition to changes in the length of the tract itself, complex movements of the tongue, teeth and 

lips cause dynamic changes in the size and shape of the vocal tract to produce the different speech 

sounds we hear.

Students were then shown a short video to demonstrate the complex movements of the human 

vocal tract. 

The following video (https://www.youtube.com/watch?v=sPp0RW3mjek) shows a real-time 

magnetic resonance imaging (MRI) recording of human singing. The video highlights the 

complex, dynamic movements in the vocal tract that produce the sounds you hear. 

The other primary way to change the resonant frequency of an object is to change the driving 

frequency at which the object vibrates. An example would be the way in which various string 

instruments resonate. Different strings are of different diameters and will vibrate at different 

frequencies. Additional frequencies can be produced by shortening the strings with the fingers. 
12

These string vibrations provide the driving frequencies for the resonance of the instrument body. 

As the driving frequency changes, so does the way in which the instrument body resonates. Take 

for example the acoustic guitar. The body of the guitar will respond differently as the driving 

frequency is changed. Figure 9 shows different vibration patterns on the back of the guitar body 

as a function of driving frequency. The different regions (or nodes) separated by the lines in the 

figure are areas where the body is vibrating. The patterns of change as frequency changes reflect 

different “modes” of vibration, and the lines represent the boundaries between nodes where there 

is no vibration. The lines between nodes are called “nodal” lines.

Fig. 9 Vibration patterns on the back of the guitar body as a function of 

driving frequency. (Image retrieved from http://en.wikipedia.org

/wiki/Ernst_Chladni#mediaviewer/File:Chladni_guitar.svg.)

One way to see these nodal lines is to place a lightweight material such as salt on the vibrating 

body, and as the body vibrates, the material will move and eventually settle along the nodal lines 

to provide a visual representation of the modes of vibration. How modes of vibration change as 

the driving frequency changes will be demonstrated in a hands-on activity using the Chladni 

plate. 

3.2.2 Interactive Topic Station: Chladni Plate

The Chladni plate is named for Ernst Chladni (1637–1692), who is best known for his work 

developing a technique for viewing the modes of vibration of a rigid surface (Chladni 2014). The 

purpose of the Chladni plate hands-on activity was to demonstrate the concept of resonance by 

using a Chladni plate built by PSB (Fig. 10) to show how the modes of vibration change with a 

change in the driving frequency (e.g., Rossing 1982). Instructors made changes in the driving 

frequency applied to a Chladni plate using a function generator and then had students draw the 

patterns of nodal lines they observed using a provided worksheet (Appendix, Resonance 

Worksheet). 
13

Fig. 10 ARL photo of Chladni plate station setup including 1) function generator, 2) audio amplifier, and 3) plate 

and loudspeaker assembly. 

3.2.3 Demonstration Equipment Setup

The Chladni plate system consisted of a 16-gauge (0.0625-inch) square 24- × 24-inch piece of 

6061 Aluminum sheet, a 12-inch ElectoVoice Woofer, an Audiosouce Monoblock 5.24-amp 

audio amplifier, and a BK Precision 3020 sweep function generator. The metal plate was affixed 

to the loudspeaker cone by a 1/4-inch-diameter threaded metal rod. At the loudspeaker end, the 

rod was bolted to a small round metal disc, which was directly affixed to the loudspeaker cone 

using hot glue. The rod ran through the original metal speaker grill to give added support to the 

sides of the rod. At the sheet metal end, the rod was affixed using washers and nuts. The 

loudspeaker was connected to and powered by the audio amplifier, and the driving signal was 

provided by the connected function generator. Fine salt crystals were spread on top of the sheet 

metal plate to provide the visualization of the changing modes of vibration. The equipment setup 

can be seen in Fig. 8. 
14

3.2.4 Demonstration Procedure

Instructors described the setup of the Chladni plate and how it works: 

The Chladni plate is a sheet of flat metal that, when vibrated at different frequencies, will 

resonate with different modes of vibration. When a lightweight material such as table salt is 

placed on top of the plate, a visual difference can be seen in how the modes of vibration change 

as frequency changes. The top plate is attached to a loudspeaker cone, and it moves with the cone. 

The vibrations in the plate are a result of the frequency of the signal from the function generator 

passing through the loudspeaker. As the signal from the function generator is changed, the salt 

patterns on the plate change due to the change in vibration of the plate.

The salt patterns that emerge as the plate vibrates at different frequencies visually demonstrate the 

modes of vibration. These changes can be seen as the salt crystals line up along the nodal lines. 

These nodal lines are areas where there is no vibration, and they form the boundaries between 

areas of vibration. The geometric patterns on the plate change as the driving frequency changes. 

During the activity, students used a provided worksheet (Appendix, Resonance Worksheet) to 

draw the patterns they saw on the Chladni plate as frequency changed. Examples of the patterns 

are shown in Fig. 11.

Fig. 11 ARL photo of Chladni Plate patterns
15

3.3 Topic 3: Bone Conduction

The topic on bone conduction introduced the concept of bone conducted hearing, explained how 

it works, and discussed the importance of bone conduction in everyday life, in nature, and in 

technology. Following the lecture, students participated at the interactive topic station for bone 

conduction and were able to view and try a variety of bone conduction devices.

3.3.1 Lecture Background

The following information was presented to the students by the lecturer to provide background 

information about the topic:

When thinking about hearing, most people think about the air conduction pathway that was 

described in the first topic lecture [e.g. Gelfand 2009]. In that pathway, sound waves in the air 

enter the ear canal and vibrate the eardrum, and the vibrations are then transmitted via the 

ossicular chain to the cochlea. However, air conduction is only one pathway through which 

people can hear sounds. The other pathway is called bone conduction. In bone conducted hearing, 

sound waves in bone and soft tissue are transmitted directly to the internal ear structures, 

bypassing the outer ear and eardrum [Henry and Letowski 2007]. 

Although the air conduction pathway is the dominant hearing pathway for humans most of the 

time, the bone conduction pathway works simultaneously and is an important part of everyday 

hearing. The bone conduction hearing pathway is of particular importance in several real-world 

experiences. For example, bone conducted hearing causes a person’s voice to sound different in 

their own head than it sounds to external listeners. People usually notice this effect when their 

voice is recorded and played back. When a person speaks, they generate sound waves in the air, 

and these sound waves travel to external recording devices, to listeners, and to the speaker’s own 

ears via air conduction. However, the speaker also generates sound waves in their own bones and 

soft tissues, and these vibrations travel to the speaker’s cochleae through bone conduction, 

influencing the speaker’s perception of their own voice. Since the speaker hears his or her own 

voice with both air and bone-conducted components, while an external recorder does not, the 

voice sounds different. 

Another example of when bone conduction is particularly important is when hearing while 

completely submerged in water. Underwater, ear canals are not in contact with external airborne 

sounds. However, humans and other mammals can still hear when swimming underwater, thanks 

to bone and tissue conduction. This can be demonstrated when submerged underwater by 

covering one’s ears and observing that sounds can still be heard. 

Bone conducted hearing is important in nature. Various animals make heavy use of bone and 

tissue conduction when perceiving sounds in the environment and when communicating with one 

another. Marine mammals such as dolphins and whales use bone and tissue conduction to hear 

sounds underwater [Au and Hastings 2008]. Bone conduction may also be important in longdistance communication in elephants, as sounds transmitted through the ground can be picked up
16

through the animals’ feet and channeled via bone and tissue conduction to internal ear structures 

[O’Connell-Rodwell 2007]. In addition, some subterranean small mammals may have become 

bone conduction specialists thanks to modified middle ear structures that enhance bone 

conduction hearing [e.g., Mason 2003].

Bone conduction in humans has multiple practical applications and can involve technological 

devices. One major application of bone conduction is in the clinical diagnosis of hearing 

disorders. Comparing a patient’s hearing performance via air conduction versus bone conduction 

can help pinpoint which area of the auditory pathway is not functioning properly. Similarly, bone 

conduction is widely used as a hearing technology for patients with conductive hearing loss, 

mixed hearing loss, or single-sided deafness. Bone conduction devices vibrate bones of the skull 

directly, thus bypassing the damage in the outer or middle ear and allowing sound to reach the 

inner ear. These devices can be surgically implanted or worn with a removable headband 

[Fig. 12]. 

Fig. 12 A bone-anchored hearing aid, a bone 

conduction device. (Image retrieved from 

http://commons.wikimedia.org/wiki

/File:BAHA_sound_processing_device_in

_place.jpg.)

Bone conduction technology can also be used in communication systems, allowing users to send 

and receive bone-conducted signals via headsets and radios. Using bone conduction instead of air 

conduction can support and improve situation awareness (by leaving ears unoccluded) in 

potentially dangerous environments such as those encountered by military personnel [Fig. 13], 

firefighters, or even joggers in traffic. Bone conduction technology can also be effectively used in 

high noise environments, such as military or industry, when accompanied by hearing protection 

devices [e.g., Pollard et al. 2014]. Outside such environments, casual-use bone conduction 

devices can provide novelty or convenience to users. Bone conduction cell phones do 
17

not need to be held to the ear and instead can be held anywhere against the skull. Bone 

conduction snorkeling headsets play music through a user’s teeth, as do musical bone conduction 

toothbrushes. 

Fig. 13 ARL photo of a Soldier wearing a bone 

conduction communication headset. The 

ears are left unoccluded to maximize 

situation awareness.

3.3.2 Interactive Topic Station: Bone Conduction Hearing

After the lecture, students moved to a demonstration table where they could view and try on a 

variety of military and commercial bone conduction devices. These included commercial 

swimming and sport headsets, as well as military headsets that incorporated a bone microphone 

and bone vibrators. Students could experience bone conduction listening through the sport 

headset, through several unmounted bone transducers, and through tuning forks. Students 

experimented with different transducer locations, static force (pressure applied between the 

transducer and skull), and ear occlusion to experience first-hand how these factors affect bone 

conduction sound transmission. Students wrote down their observations on a provided worksheet 

(Appendix, Bone Conduction Worksheet).
18

3.3.3 Demonstration Equipment Setup

The demonstration layout is displayed in Fig. 14. A portable music player (fifth generation iPod 

Classic) was used to play the sample sounds. Music, speech samples, or both would be 

appropriate sound sources. Our demo employed music played on a continuous loop, and the song 

used was “Summer Song” by Joe Satriani. This piece was selected because it is an instrumentalonly rock song with relatively constant sound levels throughout its duration.

The iPod was connected to a 4-channel Samson C-que 8-headphone amplifier, which provided 

additional sound amplification and finer control of sound volume. Four Radioear B70A bone 

vibrators were connected to the headphone amplifier so that all vibrators would play identical 

sound simultaneously. To avoid having the hard table surface act as a sound projector, the B70A 

vibrators were placed on a foam rubber pad. The bone vibrators were not attached to headbands, 

allowing students to freely experiment with the devices. Soft elastic headbands were available if 

students wished to use them. Tuning forks of different frequencies were also available for 

students to compare air-conducted hearing to bone-conducted hearing. Students could strike a 

tuning fork, listen to the sound through the air, and then touch the base of the tuning fork to their 

skull to listen through bone conduction. A set of 5 standard metal tuning forks was laid out on 

the table for students to try.

Fig. 14 ARL photo of the bone conduction station including 1) full-face respirator with Huari HRE-5673 

system, 2) Samson C-que 8-headphone amplifier, 3) iPod, 4) Finis SwiMP3, 5) Goldendance Double 

Bone, 6) Temco HG-17, 7) Radioear B70A bone vibrators, 8) Aftershokz Sport headset, 9) 

Amphicom Aqua FM, and 10) tuning forks. 
19

In addition to the loose vibrators and tuning forks, a variety of commercial and military bone 

conduction devices were displayed. Commercial bone conduction devices in our demo included 

an Amphicom Aqua FM bone conduction snorkeling system, a Finis SwiMP3 swim goggle 

system, and an Aftershokz Sport casual use bone conduction headset. The SwiMP3 played music 

through its built-in system; the Aftershokz Sport could be attached directly to the iPod for 

demonstration. The military headsets displayed included combined bone conduction vibrator and 

bone conduction microphone capability. In addition, a bone conduction communication system 

designed for gas masks (Huari HRE-5673) was displayed attached to a military full-face 

respirator (M50 Joint Service General Purpose Mask). Alcohol-based sanitary wipes were used 

to wipe down the equipment.

3.3.4 Demonstration Procedure

The bone conduction station was a hands-on activity wherein each student could be experiencing 

a different item simultaneously and could self-select which items they wanted to experience. The 

instructor conveyed information in an informal manner, ordered and emphasized differently 

depending on the interests displayed by each group of students. Thus, this section is a procedural 

summary of their general experiences. 

Students were first introduced to the Radioear B70A bone conduction vibrators. The instructor 

explained that the smooth curved side of the vibrators should be placed against the skull or 

mandible to transmit the sound via bone to the listener’s inner ears. Once the students tried this 

and confirmed that they could hear the bone-conducted sounds, they were encouraged to 

experiment with different skull locations, to try different pressure levels, and to try different 

numbers of vibrators used simultaneously. Students were offered soft elastic headbands if they 

wanted to use them to secure the vibrators to their heads. If the students did not spontaneously 

try key skull locations (such as the mastoid process behind the ear, the mandibular condyle in 

front of the ear, or the center of the forehead), then the locations were suggested. The instructor 

mentioned that skull location, static force, and number of vibrators are active areas of study in 

bone conduction research, as scientists are learning how to optimize bone conducted sound 

transmission and wearing convenience for different applications. After students experimented 

with different configurations, they were instructed to occlude their ears with their fingers or with 

the previously provided earplugs and compare the quality of the bone-conducted sound in both 

occluded and unoccluded conditions. The instructor reminded students that bone conduction can 

be used with ears unoccluded to permit situation awareness of the surrounding environment, and 

that bone conduction can be used with occluded ears (i.e., with hearing protection) when in high 

noise environments. Students were given time to perform the occlusion experiment and to try out 

different skull locations, pressures, etc. in the occluded and unoccluded condition. Students 

wrote their observations down on the provided worksheet (Appendix, Bone Conduction 

Worksheet).
20

Students were then introduced to the tuning forks. Students were instructed to strike the forks on 

the rubber soles of their shoes and to hold the stem of the fork to prevent quelling the vibrations. 

The instructor demonstrated placing the bottom tip of a vibrating tuning fork against the skull to 

hear the vibration via bone conduction. Students were then allowed to experiment with different 

frequencies of tuning forks, heard through the air and through bone, and with and without ear 

occlusion.

Finally, students were introduced to the commercial and military bone conduction headsets on 

display. The instructor explained the function of the commercial and military headsets. The Finis 

SwiMP3 goggles and Amphicom Aqua FM snorkel allow a person to listen to music or radio 

while swimming, and the Aftershokz Sport is intended for use while walking, jogging, or other 

casual activities. For the military headsets, bone conduction microphones were explained. The 

instructor asked students to recall the fact that speaking generates vibrations in the air and in the 

speaker’s bones. It was then explained that a bone conduction microphone is designed to pick up 

the bone vibrations generated when a person speaks. Students were permitted to try on any of the 

headset devices (except the snorkel), and alcohol wipes were available to clean the equipment 

between uses. Because of time and space constraints, students did not acoustically test the 

military bone microphone systems but were allowed to try them on if they wished.

4. Conclusion

The objective of GEMS is to educate students with information in areas of science, engineering, 

mathematics, computational sciences, computation biology, biomedical sciences, chemistry, and 

biology that they would not normally be exposed to in school. The instructors provided students 

with age-appropriate lecture material and interactive activities to demonstrate topics related to 

research within the PSB laboratory. The 3 topics included 1) anatomy and physiology of hearing 

with a special focus on hearing conservation, 2) acoustic resonance, and 3) bone conduction 

hearing. Students were provided with handouts of the lecture material to have as a reference. In 

addition, PSB presenters discussed their educational backgrounds and job positions to expose 

students to different job opportunities and career paths. The purpose of this technical report is to 

document the lecture and demonstration materials that were developed for this program. These 

materials can be used for future outreach programs.
21

5. References

Au WWL, Hastings MC. Auditory systems of marine animals. In: Principles of marine 

bioacoustics. New York (NY): Springer; 2008. 227–282.

Denes PB, Pinson EN. The speech chain. New York (NY): Macmillan; 1993.

Ernst Chladni. Wikipedia. [updated 2014 Oct 4; accessed 2014 Nov] 

http://en.wikipedia.org/wiki/Ernst_Chladni

Gelfand SA. Essentials of audiology. 3rd ed. New York (NY): Thieme Medical 2009.

Henry P, Foots A. Comparison of user volume control settings for portable music players with 

three earphone configurations in quiet and noisy environments. Journal of the American 

Academy of Audiology. 2012;23:182–191.

Henry P, Letowski T. Bone conduction: anatomy, physiology, and communication. Aberdeen 

Proving Ground (MD): Army Research Laboratory (US); 2007. Report No.: ARL-TR-4138. 

Also available at http://www.arl.army.mil/www/default.cfm?technical_report=1394.

Howard DM, Angus J. Acoustics and psychoacoustics. New York (NY): Taylor and Francis; 

2009.

Mason, MJ. Bone conduction and seismic sensitivity in golden moles (chrysochloridae). Journal 

of Zoology. 2003;206(4): 405–413.

Occupational Noise Exposure. Cincinnati (OH): National Institute for Occupational Safety and 

Health (US); 1998. NIOSH Publication No.: 98–126. 

O’Connell-Rodwell CE. Keeping an “ear” to the ground: seismic communication in elephants. 

Physiology. 2007;22:287–294.

Pollard KA, Garrett L, Tran P. Bone conduction systems for full-face respirators: speech 

intelligibility analysis. Aberdeen Proving Ground (MD): Army Research Laboratory (US); 

2014. Report No.: ARL-TR-6883.Also available at 

http://www.arl.army.mil/www/default.cfm?technical_report=7054. 

Rossing TD. Chladni’s law for vibrating plates. American Journal of Physics. 1982;50(3):

271–274.
22

INTENTIONALLY LEFT BLANK.
23

Appendix. Environment for Auditory Research (EAR) Presentation 

 

This appendix appears in its original in its original form, without editorial change.
24 

Environment for Auditory 

Research (EAR) 

0 -·---·---· 

GEMS 2014 

Overview 

~-----------() -------------~ 

• Healing & Hearing Conservation 

o Activity with Portable Media Player 

• Resonance 

o Chladni Plate Demonstration 

• Bone Conduction 

o Activity with Bone Conduction Headsets 
25 

Anatomy 

~----------- () -------------~ Exremalear Mlddltear 

r----A--------~ r---/''---~ 

External LC~~~~~~~~jillll~ auditory 

canal 

1---------
26 

Hair Cells 

1--------0 ---------l 

Normal hair cells (left) Damaged hair cells (right) 

Dancing Hair Cell 

0 -

Video - mm: h!lp1l!u!!il!!ryne!!.-ochJ - eel 
27 

Hearing Conservation 

0 - " ~-

165 = 

... Contir,uousdB Permi»ible Expo)ure Time 14.S = 

135 =.:--... 

85 d6 8 Hours 125 -

88d6 

t~ 4 hours 115 =-

105 

91 d6 2 hours -- 9~ -- 94d6 1 hour Oi =. 

-.. 

97 d6 I 30 minutes 7S = 

100cB 15 minutes ., 

103 cB 7.5 minutes ss = 

106cB 3.75 minutes(< 4 min) ., - 109cB .875 minutes(< 2 min) l5 

112 cB l .9375 mm (-1 min) 25 

- 115 cS 4687S mrn ( 30 sec) '" IS 

- s 

0 :.:-::: 

(!) 

lmagesrarievedfrom: t821lwNw..c810eR111_... itWa omlecllcalioru111bllllltiol..a.1B t..B ~18-&ne-qidelltee/ 

Ways to Protect your Hearing 

r----------0 ---------l 
28 

Activity: Portable Media Player 

~------- ---------~ 

Portable Media Player Worksheet 

Relative listening Level (RL) 

Listening Level (LL) LL = CV offset+ RL 

Permissible Exposure time: 
29 

 

-

Concept of Resonance 

~-----------() -------------~ 

• ALL OBJECTS HAVE NATURAL RESONANT 

FREQUENCY(S) 

• RESONANT FREQUENCY CAN CHANGE BASED ON: 

1) Changes in size and shape of th e object 

2) Changes in the <hiving frequencies 

• RESULT IN CHANGES IN MODES OF VIBRATION 

• EXAMPLES: 

• Speech Articulation 

• Musical Instruments 

• Chladni Plate 

REAL-TIME MRI OF SPEECH 
30 

Activity: Chladni Plate Demonstration 

1-------0 -------l 

Like the guitar example, changing the driving frequency changes the modes of 

vibration across the plate. 

Resonance Worksheet 

Draw the patterns you observe for each driving frequency. 

Driving Frequency Driving Frequency Driving Frequency 

______ ,Hz ______ ,Hz ______ Hz 

Driving Frequency Driving Frequency Driving Frequency 

______ ,Hz ______ ,Hz ______ Hz 
31 

Air Conduction vs. Bone Conduction 

~-----------() -------------~ 

Air Conduction Hearing 

Cochlea 

Mastoid bone 

IJ.-I.-"11 Facial nerve 

Bone Conduction Hearing 
32

Bone Conduction Uses

 Hearing assessment & hearing aids

 Noisy environments

 Worn with hearing protection

 Military, industry, vehicles

 Situation awareness

 Ears open to outside sounds

 Military, firefighters, police, joggers, 

casual use

 Just for fun

 Cell phones, toothbrushes, swimming

Images retrieved from:

http://commons.wikimedia.org/wiki/File:CES_2012_-_Aftershokz_bone_conduction_headphones_%286937588341%29.jpg 
33 

 

Activity: Bone Conduction Demonstration 

--0 ---

Bone Conduction Worksheet 

1. What were you listening to? 

ic speech 

2. Try I:Gtening at different skull locations. What skuiJ locations did you tty? List a:t least three. 

l . Does tt.e sound differ arnol\g tt.e different skull locations? Describe. 

4. Listen bothow ith your ears p1ugged and not plugged. How does the sound differ in these two condit ions? 

S. What is one application or situation where bone ond uctio ~ useful? Wby is bone conduction useful for this application or situation? 
34 
35

List of Symbols, Abbreviations, and Acronyms

ARL US Army Research Laboratory 

GEMS Gains in the Education of Mathematics and Science 

HRED Human Research and Engineering Directorate

KEMAR Knowles Electronic Manikin for Acoustic Research

LL listening level

NISOH National Institute for Occupational Safety and Health

PC personal computer

PSB Perceptual Sciences Branch

RL relative level

STEM science, technology, engineering, and mathematics
36

1 DEFENSE TECHNICAL

(PDF) INFORMATION CTR

DTIC OCA

2 DIRECTOR

(PDF) US ARMY RESEARCH LAB

RDRL CIO LL

IMAL HRA MAIL & RECORDS MGMT

1 GOVT PRINTG OFC

(PDF) A MALHOTRA

1 ARMY RSCH LABORATORY – HRED

(PDF) RDRL HRM D

T DAVIS

BLDG 5400 RM C242

REDSTONE ARSENAL AL 35898-7290

1 ARMY RSCH LABORATORY – HRED

(PDF) RDRL HRS EA DR V J RICE

BLDG 4011 RM 217

1750 GREELEY RD

FORT SAM HOUSTON TX 78234-5002

1 ARMY RSCH LABORATORY – HRED

(PDF) RDRL HRM DG J RUBINSTEIN

BLDG 333

PICATINNY ARSENAL NJ 07806-5000

1 ARMY RSCH LABORATORY – HRED

(PDF) ARMC FIELD ELEMENT

RDRL HRM CH C BURNS

THIRD AVE BLDG 1467B RM 336

FORT KNOX KY 40121

1 ARMY RSCH LABORATORY – HRED

(PDF) AWC FIELD ELEMENT

RDRL HRM DJ D DURBIN

BLDG 4506 (DCD) RM 107

FORT RUCKER AL 36362-5000 

1 ARMY RSCH LABORATORY – HRED

(PDF) RDRL HRM CK J REINHART

10125 KINGMAN RD BLDG 317

FORT BELVOIR VA 22060-5828

1 ARMY RSCH LABORATORY – HRED

(PDF) RDRL HRM AY M BARNES

2520 HEALY AVE 

STE 1172 BLDG 51005

FORT HUACHUCA AZ 85613-7069

1 ARMY RSCH LABORATORY – HRED

(PDF) RDRL HRM AP D UNGVARSKY

POPE HALL BLDG 470 

BCBL 806 HARRISON DR

FORT LEAVENWORTH KS 66027-2302

1 ARMY RSCH LABORATORY – HRED

(PDF) RDRL HRM AT J CHEN

12423 RESEARCH PKWY

ORLANDO FL 32826-3276

1 ARMY RSCH LAB – HRED

(PDF) HUMAN SYSTEMS

INTEGRATION ENGR

TACOM FIELD ELEMENT

RDRL HRM CU P MUNYA

6501 E 11 MILE RD 

MS 284 BLDG 200A 

WARREN MI 48397-5000

1 ARMY RSCH LABORATORY – HRED

(PDF) FIRES CTR OF EXCELLENCE 

FIELD ELEMENT

RDRL HRM AF C HERNANDEZ

3040 NW AUSTIN RD RM 221

FORT SILL OK 73503-9043

1 ARMY RSCH LABORATORY – HRED

(PDF) RDRL HRM AV W CULBERTSON

91012 STATION AVE 

FORT HOOD TX 76544-5073

1 ARMY RSCH LABORATORY – HRED

(PDF) RDRL HRM DE A MARES

1733 PLEASONTON RD BOX 3

FORT BLISS TX 79916-6816

8 ARMY RSCH LABORATORY – HRED

(PDF) SIMULATION & TRAINING

TECHNOLOGY CENTER

RDRL HRT COL G LAASE

RDRL HRT I MARTINEZ

RDRL HRT T R SOTTILARE

RDRL HRT B N FINKELSTEIN

RDRL HRT G A RODRIGUEZ

RDRL HRT I J HART

RDRL HRT M C METEVIER

RDRL HRT S B PETTIT

12423 RESEARCH PARKWAY

ORLANDO FL 32826

1 ARMY RSCH LABORATORY – HRED

(PDF) HQ USASOC

RDRL HRM CN R SPENCER

BLDG E2929 DESERT STORM DRIVE

FORT BRAGG NC 28310
37

1 ARMY G1

(PDF) DAPE MR B KNAPP

300 ARMY PENTAGON RM 2C489

WASHINGTON DC 20310-0300

ABERDEEN PROVING GROUND

12 DIR USARL

(PDF) RDRL HR

L ALLENDER

P FRANASZCZUK

RDRL HRM

P SAVAGE-KNEPSHIELD

RDRL HRM AL

C PAULILLO

RDRL HRM B

J GRYNOVICKI

RDRL HRM C

L GARRETT

RDRL HRS

J LOCKETT

RDRL HRS B

M LAFIANDRA

RDRL HRS C

K MCDOWELL

RDRL HRS D

A FOOTS

A SCHARINE

RDRL HRS E

D HEADLEY
38

INTENTIONALLY LEFT BLANK.