Technical Reports
A technical report is a technical document that records and disseminates methods and results from research studies and research, development, test, and evaluation (RDT&E) activities. Technical reports are USAARL's principal method of in-depth reporting on technical subjects that are of interest not only to the department, agency, or command sponsoring the work, but also to external groups and laboratories in government, academia, and industry. Technical reports may vary in type, to include technical reports that present the findings of research or analyses or that provide guidance or instruction on matters important to the DoD, journal articles (open access and embargoed text) that have been published under an open access agreement with the publisher or published under a Creative Commons license, conference proceedings that include whole collections of papers presented at a symposium or workshop, and conference papers that could include an individual paper, briefing charts, or a poster presented at a workshop or symposium. For inquiries related to USAARL's technical report(s), contact usarmy-usaarl-library@health.mil.
Featured Reports
For more reports, please visit the technical reports archive page.
TITLE:Army Aviator Hearing Trends: 2016-2023
AUTHOR(s):Noetzel, J., Henry, P., Stefanson, JR, & Jones, H.
ABBREVIATED ABSTRACT:Two Army databases were used to determine the current prevalence and severity of hearing loss among Army aviators and to determine the degree to which waivers are issued for hearing function. Data pulled from the Defense Occupational Environmental Health Readiness System (DOEHRS) database across years 2016 and 2020 along with data pulled from the Aeromedical Electronic Resource Office (AERO) across 1 January 2020 to 11 December 2022 were compared to give an overall picture of the rates of hearing loss. The results of the DOEHRS analysis demonstrated about 6% of the aviator population presented with hearing loss outside the standard identified in the Aeromedical Policy Letter. The results of the AERO analysis demonstrated that approximately 100 waivers are submitted each year, indicating that 1% of Army aviators have a new hearing loss diagnosis. Aviators who fall outside of the standard were nearly always provided a waiver if they were already trained (upon entry) or, if the waiver was needed for continued service. Further research is needed to determine the degree to which aviator performance is impacted by hearing loss that exists beyond the standard.
KEYWORDS:hearing loss, aviation, fitness for duty
TITLE:The Effects of Simulated Hearing Loss on Aviator Performance and Cognitive Workload During Simulated Flight
AUTHOR(s):Jones, H., Noetzel, J., Henry, P., Hale, K., Andres, K., Mackie, R., Yue, X., McCormick, R., Lee, K., & Stefanson, JR
ABBREVIATED ABSTRACT:Hearing loss can render an aviator more susceptible to the adverse effects of degraded communication signals and consequently lead to an increased allocation of mental resources to the task of processing radio communications (referred to as listening effort). The current study investigated the impact of simulated hearing loss on functional hearing assessments, flight performance, and cognitive workload of military-trained rotary-wing pilots. Subjects underwent current standard clinical audiometric testing and performed simulated rotary-wing flights. Two listening conditions, normal hearing and one of two simulated hearing loss, were tested. Clinical testing was conducted in a sound-treated audiometric booth using a tablet-based system and aviation communication earplugs. Simulated flight performance data were collected from pilots operating a full-motion UH-60 Black Hawk flight simulator at the U.S. Army Aeromedical Research Laboratory. Aviator performance was compared in high and low workloads across the different hearing conditions. Simulated hearing loss decreased all audiometric testing speech scores and decreased speech intelligibility in the flight simulator as well indicating that the larger the hearing deficit, the more missed or incorrect calls subjects had on average. Findings from this study will be leveraged in developing future protocols for aeromedical standards and provide data for the development of operator state monitoring capabilities.
KEYWORDS:hearing loss, workload, aviation
TITLE:Evaluation of a Novel Wearable EEG/EOG Sensor for Real-Time Operator State Monitoring
AUTHOR(s):D'Alessandro, M., Yue, X., Mackie, R., Barnett, J., Baugher, K., Duffy, M., Feltman, K., Huh, H., Shin, H., & Lu, N.
ABBREVIATED ABSTRACT:Real-time monitoring of pilots' cognitive state using psychophysiological measurements is critical for aviation safety. However, current laboratory-grade electroencephalography (EEG) devices require extensive wired electrodes and setup, limiting feasibility for in-flight use. This study evaluated wireless prototypes consisting of a four channel EEG and two channel electrooculography (EOG) forehead sensor to assess their potential to monitor cognitive state during flight. The sensor utilizes flexible dry electrodes and minimal setup. Comparisons to laboratory EEG were done across varying workload tasks. However, signal contamination at 30 Hertz (Hz), potentially from hardware issues, prevented EEG data analysis. Enhanced durability is critical for unreliable environmental settings along with pre-deployment functionality checks. Despite current issues, the compact sensor shows promise if functioning reliably. Considerable further development and rigorous in-flight testing is required before adoption. With refinements ensuring robust data quality, the sensor concept holds promise for objectively monitoring hazardous states like excessive workload and fatigue in-flight. Once thoroughly validated for flight conditions, similar forehead prototypes may someday fill the pressing need for real-time mental state monitoring to enhance aviation safety.
KEYWORDS:electroencephalography (EEG), operator state monitoring (OSM), mental workload
TITLE:Continuous Physiological Monitoring of the Combined Exposure to Hypoxia and High Cognitive Load in Military Personnel
AUTHOR(s):Temme, L., Wittels, H., Wishon, M., St. Onge, P., McDonald, S., Heckocks, D., & Wittels, S.
ABBREVIATED ABSTRACT:The health and safety of military aviators is paramount during flight operations. In flight, aviators experience extreme environmental conditions such as high altitude, which reduces oxygen availability to the brain and compromises the function of all bodily systems. The autonomic nervous system (ANS) regulates many of the bodily systems, and therefore its function is a strong indicator of the physiological consequences to prolonged exposure to less oxygen. Importantly, aviators spend most of their flight time at less severe altitudes. However, even mild decrements in oxygen may elicit suboptimal function of the ANS, compromising aviator safety. What remains less clear is how the exposure to mild reductions in oxygen while simultaneously performing simulated flight tasks affects the ANS. The current study investigated this question by exposing aviators to varying levels of oxygen while carrying out simulated flight tasks. The aviators' ANS responses were measured throughout the nearly two hours of trials. Our study observed heightened sympathetic nervous system activity (e.g., "fight or flight") and found suggestions of increased anxiety. Lastly, we found that the timing and extent of the ANS responses differed between conditions. These observations highlight the importance of monitoring several markers of ANS function to avoid deteriorating aviator function when flying at mild altitudes.
KEYWORDS:hypoxia, hyperoxia, aviation, military, autonomic nervous system, heart rate variability, sympathetic nervous system
TITLE:Medical Standard Considerations for the Implementation of Spatial Audio in Aviation
AUTHOR(s):Noetzel, J., Henry, P., Stefanson, JR, & Jones, H.
ABBREVIATED ABSTRACT:As the Army advances its force modernization priorities, the development of Future Vertical Lift (FVL) aircraft has become an area of concentrated effort. Tremendous focus placed on extending the reach of current rotary-wing aircraft and operating over new terrains will allow completion of novel mission sets. Given the ambitions of FVL aircraft operations (i.e., high-altitude desert plateau and the urban canyons of megacities), it is imperative the aviator is provided with state-of-the-art technologies and capabilities aimed at increasing an operator's situational awareness, enabling safe operations, optimizing crew performance, and reducing pilot fatigue. One potential solution is the implementation of spatial auditory display technologies (i.e., 3D audio displays). Spatial auditory displays support a natural, ecologically valid, egocentric representation of space where auditory objects behave realistically in terms of direction, distance, and motion. The present report details the state of science for spatial audio displays in aviation, considerations for medical standards and biomedical design criteria, an overview of current Department of Defense hearing standards, and highlights the various applications for which spatial audio could benefit the aviator.
KEYWORDS:hearing loss, medical standards, aviation, spatial audio
TITLE:Evaluation of a Transparent Seat Back for Motion Capture of the Thoracolumbar Spine on the Multi-Axis Ride Simulator
AUTHOR(s):Ballard, M., Hasapes, S., Robinette, A., Stewart, A., Perkins, S. M., Prusia, M., Shumate, S., Madison, A., & Chancey, V. C.
ABBREVIATED ABSTRACT:Low back pain is a pervasive health problem in a range of military occupations. A knowledge gap exists regarding spinal movement in operational ride environments due to limitations in data collection caused by equipment impeding motion capture data collection. This involves the development and validation of a novel transparent seat back (TSB) for the USAARL multi-axis ride simulator (MARS) to develop a standard methodology to quantify seated spinal motion response to whole-body vibration (WBV) and jolt during simulated operational transport environments. The TSB was fabricated and affixed to the standard MARS chair instead of the aluminum seat back. Volunteers were instrumented and asked to perform torso movements within all three planes. Vicon motion capture was used to observe visual distortions through the transparent seat back. Data were collected for a 35th percentile female and capture was used to observe visual distortions through the transparent seat back. Data were collected for a 35th percentile female and 95th percentile male, and x-, y-, and z-positional data were analyzed. Results indicate that the retroreflective markers can be tracked regardless of TSB configuration with minimal error or distortion. The TSB will add to vibration research capabilities.
KEYWORDS:low back pain, LBP, military back pain, whole-body vibration, WBV, motion capture, Vicon, transparent seat back, seated spinal kinematics, spinal motion, spinal motion capture, thoracolumbar spine
TITLE:Efficacy of Medical Device Alarm Integration into a Simulated H-60 Integrated Communication System
AUTHOR(s):Kroening, L., Kinsler, R., Molles, J., & Lloyd, A.
ABBREVIATED ABSTRACT:Introduction: This study sought to examine the efficacy of integrating medical device alarms into the intercommunication set of a simulated HH-60, allowing medics to hear the alarms over the ambient noise of the aeromedical environment. Materials and Methods: U.S. Army critical care flight paramedics were recruited as subjects for this study. Subjects participated in two testing scenarios: one with patient monitor alarms integrated into their communication lines and one without integrated alarms (the control condition). Testing took place in a simulated HH-60 interior with two priority-level patients per testing scenario, one on either side of the interior. Subjects provided care to these two patients for 30 minutes per scenario. After both scenarios were complete, the subjects were given a questionnaire to obtain their feedback on alarm integration. Results: Six subjects took part in this study, so the results do not have sufficient power to represent the population. No statistically significant results were found. Looking at the trends in the data, implementing alarm integration showed the indications of reducing reaction time to alarms, decreasing or matching the amount of time spent with the patient monitor, and equivalent amounts of time dedicated to patient treatment when compared to the nonintegrated scenario. The feedback obtained from the subjects provided a list of perceived benefits, drawbacks, and improvements related to the integration of medical device alarms into the intercommunication set. Conclusions: Although the study was underpowered, the trends in the data indicate a benefit to the medics when integrating medical device alarms. When coupled with strongly favorable end-user feedback, the results provide justification for pursuing the effort of integrating alarms and performing future studies with improved integration systems to optimize the potential of the system.
KEYWORDS:integrated communication set, ICS, communication ear plugs, CEPs, U.S. Army, helicopter, HH-60, baseline medical interior, BMI, medical evacuation, MEDEVAC, patient care, medical device, monitor, vital signs
TITLE:Methodology and Considerations for Combining Historic Accelerative Loading Research to Update the U.S. Army Aeromedical Research Laboratory Head-Supported Mass Injury Curve Using Survival Analysis
AUTHOR(s):Brozoski, F., Duemmler, M., McGovern, S., Rhodes, D., Vasquez, K., Johnson, B., Beltran, C., Madison, A., & Chancey, V. C.
ABBREVIATED ABSTRACT:Military helmets are multi-functional tools that provide blunt and ballistic impact protection and are frequently used as a mounting platform for life support and operational enhancement technologies. The frequent use of these helmet-mounted technologies can increase the risk of cervical spine injury, both acute and chronic, to Warfighters due to the increase in head-supported mass (HSM) and changes in the location of the combined center of mass (CM) of the helmet and helmet-mounted technologies. Evidence of an increased neck injury risk was provided through epidemiological research. This evidence led the U.S. Army Aeromedical Research Laboratory (USAARL) to investigate and develop HSM requirements for Army rotary-wing helmets in 1997 (McEntire & Shannahan, 1997). Over the 25 years since the introduction of the USAARL HSM Curves, additional research has been conducted into the effects of HSM and HSM CM location.
KEYWORDS:head-supported mass, HSM, retrospective review, survival analysis, center of mass
TITLE:Evaluation of a Multisensory Cueing System on Aviators' Performance: Impact of Tactile and Auditory Cueing Sensitivity Levels
AUTHOR(s):Feltman, K., Mackie, R., McAtee, A., Aura, C., Noetzel, J., Wilkins, J., Yue, X., McCormick, R., Alcock, S., & Gerstner, J.
ABBREVIATED ABSTRACT:The present study sought to evaluate the utility of a multisensory cueing system on aviators' ability to maintain performance, their experience of workload, and its impact to their situation awareness. Four combinations of cueing sensitivities were evaluated: high auditory/low tactile, high auditory/high tactile, low auditory/low tactile, and low auditory/high tactile. From this study it was concluded that cueing configurations featuring low auditory sensitivity were preferred in terms of performance. Additionally, the majority of participants indicated preference of the configuration featuring low auditory/high tactile cueing, which was also reflected in their workload ratings and performance data.
KEYWORDS:aviation, multisensory cueing, flight performance
TITLE:Instrumented Mouthguard Laboratory Evaluation using Two Anthropometric Test Device Headforms
AUTHOR(s):Brown, B., Daniel, R., & Rooks, T.
ABBREVIATED ABSTRACT:This study is in support of the Human Head Impact Dose Concussion Risk Functions and Sensor-Based Military-Specific Environmental Monitoring System project (BA150149, W81XWH-17-1-0019). Test methods and results comparing the measured kinematics using a boil-and-bite instrumented mouthguard with reference kinematics from two ATD headforms under multiple exposure types and severities are provided. Mouthguard performance was comparable to prior literature; however, there was an increase in variability due to fitting. The Mandible Load Sensing Headform resulted in poor comparisons between the mouthguard and the reference due to several issues with jaw movement and interactions with the mouthguard. A modified NOCSAE headform resulted in good comparisons between the mouthguard and reference data. Increased variability in mouthguard response compared to the reference was primarily attributed to the use of boil-and-bite versus fully custom-molded mouthguards commonly used in the literature. While increased, when compared to custom-molded mouthguards, the variability was still minimal.
KEYWORDS:environmental sensor, concussion, traumatic brain injury, TBI, mTBI, wearable sensor, concussion monitor, head impact sensor, ESiT
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Last Modified Date: 2023-04-14