TECHNOLOGY AREA(S): Human Systems

ACQUISITION PROGRAM: PM � Infantry Combat Equipment, Ground Combat Element Systems Marine Corps SYSCOM (PM ICE GCES MCSC)

OBJECTIVE: Develop an auditory situation awareness (ASA) training-measurement system that will both measure and provide practice for the Marine warfighter and Naval ship deck crew member in maintaining auditory situation awareness when using tactical communication and protection systems (TCAPS), communications headsets, hearing protection devices (HPDs), or with the open ear.

DESCRIPTION: Although the Navy as well as other military branches recognizes the importance of providing appropriate HPDs, communications headsets and TCAPS to soldiers to prevent noise-induced hearing loss, currently there is neither a standard nor generally agreed-upon method to measure auditory situation awareness afforded by such devices, nor agreement on the elements such a test would include.� This topic looks to develop such measurement techniques and contribute to the development of appropriate standards.� It has been clearly demonstrated in several empirical human factors experiments that certain advanced HPDs and TCAPS compromise the wearer's auditory situation awareness, as compared to that provided by the open ear, for various tasks which may include detection, recognition/identification, localization, and pass-through communications (1,2,3,4).� With these scientific data in hand which demonstrate the deleterious effects of certain HPDs and TCAPS on the hearing of signals and speech, it is now incumbent in future procurement of such devices to evaluate them with an objective test battery prior to selection and deployment.� Furthermore, it is essential to train personnel who must accomplish missions which depend upon auditory situation awareness, about how to improve their situation awareness on multiple task elements with the open ear alone, and with a particular HPD or TCAPS which might be assigned to them.� It has already been demonstrated in a recent dissertation experiment that the human hearing sense has "plasticity," and can indeed be trained to improve performance on complex localization and recognition/identification tasks, both with and without occlusion of the ear (5,6).

An ideal measurement-training system is anticipated to be a fully automated system that will provide an immersive simulation that employs both visual displays and auditory cues for the recognition/identification element and localization element of auditory situation awareness.� The system should be operable by a Marine or Navy "trainee" who will be assigned a TCAPS or an HPD, and not require a laboratory experimenter or technician to oversee the measurement and training.� The system should be able to stop/pause when the trainee reaches certain predetermined performance level, and provide continuous performance feedback at all times.� Performance milestone criteria will be required in order to determine when the trainee can advance to the next level, or simply needs to be assigned a different product due to training difficulties.� The system should also incorporate a modular design so that additional signals and background noises can be easily added after final system development, to render the system applicable to a variety of mission scenarios for which personnel training would be beneficial.� The system should also include a software module to semi-automate the system's acoustical calibration.

The proposed training system's display must be auditory only (no visual strobe or other light displays).� The auditory localization signals will be highly directional, and vectored toward the listener, so as to not disturb others in the vicinity.� Signals are preferred to be at a supra-threshold level, to ensure reliable detection and then localization, but loud presentations are unnecessary and undesirable.� Care must be taken in design not to disturb others who are in the vicinity.� For this reason, both the to-be localized signals and any added background sounds will be presented at levels that are only slightly higher than that of ambient sound of the installation facility.� The basic localization test signal sounds may be the composite signal sounds (as used in other test batteries), and should include both low and high frequency components to take advantage of interaural time and interaural level differences, respectively.� Task/mission specific sounds are desirable as well.� In addition to maintaining signal levels at supra-threshold but not disturbingly loud levels, the installation kit may employ sound absorbing curtains or lightweight baffles to limit sound leakage to nearby rooms.

The training system hardware and control laptop should be designed so that entire kit will fit into two "suitcase-style" standard aluminum or plastic storage cases, with a maximum size of 4ft L x 3ft W x 2ft H each.� It is expected that the loudspeaker setup will be mounted on an expandable, gimbaled, telescoping, or other design that can be quickly "broken-down" into transportable configuration.� Once assembled, which should require less than 15 minutes, followed by five minutes of calibration, the fully installed loudspeaker system should be less than about 6.5ft in diameter with a trainee seated at the center.� Disassembly should require approximately the same amount of time as assembly.

The training-measurement system will provide immediate performance feedback with the goal of improving the wearer's auditory situation awareness, both with the open ear and while occluded with a TCAPS or HPD, in order to familiarize the user with the device and improve their situation awareness performance prior to deployment.� The auditory situation awareness system must include objective, quantitative measurement on at least the tasks of auditory recognition/identification and localization.� The system will afford introduction of various background noise spectra at different sound levels to simulate a variety of mission environments that are typically encountered by Marine and Naval personnel.� The sound level of both background noise and the test-training signals will be adjustable so that multiple signal-to-noise ratios can be evaluated.� For the recognition/identification task, the system should allow the use of highly realistic, mission-specific sounds that would be encountered in the environments of interest where HPDs or TCAPS may be employed.� For the localization task, the system should provide measurement and training in both azimuthal plane (i.e., 360-degrees in horizontal) and frontal elevation.� Loudspeakers should be arranged with at least 15-degrees of separation for both subtests.� For both measurement and training purposes, the system will provide metrics of both accuracy (correctness of response) as well as response time, and immediate trial-by-trial feedback on both types of metrics will be seamlessly provided to the trainee during a testing-training session.� The system will have the dual capability of being amenable to application for personnel training purposes or for device evaluation and procurement decisions, or both.

PHASE I: Demonstrate the feasibility of a training-measurement system that will measure performance, both accuracy and response time, for the recognition/identification and localization components of auditory situation awareness.� This will be applicable to military trainees with HPDs, headsets, and TCAPS under at least 3 signal-to-noise ratios and various background noises, and compare the performance to the open ear.� For the sound localization element, the system will measure at least 15-degrees of separation or smaller, in 360-degrees of azimuth and 60-degrees of frontal elevation.� It should measure at least similar ASA task elements as in a prior-developed DRILCOM1 test battery or similar, and test various combinations of visual displays and control input devices.� It shall establish situation awareness performance goals and milestones of performance.� The outcomes of Phase I report will yield a Phase II developmental schedule that contains discrete milestones for actual system development and plans for a prototype in Phase II.

PHASE II: Develop a prototype training-measurement system that incorporates both visual and auditory displays in accordance with the Phase II developmental schedule created in Phase I.� Conduct a full ergonomics task analysis review (i.e., not requiring human subject testing) to ensure the training system�s capabilities are accommodated, primarily by measuring inter-device differences via physical microphone-analyzer testing to ascertain the signals' acoustical characteristics in-situ.� The training system should be fully automated and a user should be able to initiate the training program and finish without any major intervention/control from a trainer; this will also be subjected to a task analytic review.� The system should include semi-automated calibration program that will enable calibration of the system by a minimally trained experimenter.

PHASE III DUAL USE APPLICATIONS: Develop a fully automated training system with a calibration program and hardware installation kit that is intended for use by an individual trainee on themselves for practice and learning purposes.� The installation kit will enable installation of the training-measurement system by one having minimal technical skills in acoustics and without extensive effort.� The modular program will allow future increments of the training scenarios and their associated performance metrics to accommodate training for various missions that could be encountered, making the system useful for a variety of military MOS (Military Occupation Specialties).� The system will provide a means to train warfighters with various devices and with the open ear on the two auditory situation awareness tasks, and a means to measure the initial performance levels that soldiers with a device can be expected to achieve without any training.

Beyond the aforementioned military applications, the localization training-acclimation system has strong potential benefits for civilian workplace applications.� For instance, in road construction, the localization of horns and backup alarms on moving equipment is critical, and many run-over accidents occur when these warning signals cannot be localized.� Furthermore, in manufacturing plants, forklifts and remotely-guided materials handling vehicles have reverse alarms and motion beepers, respectively, to warn workers of their positions. �Any worker in these highly dynamic environments must be cognizant of the location of dangerous equipment that moves in their vicinity.� Furthermore, these workers are also frequently wearing hearing protection due to noise exposures.� Thus, workers need training on the tasks of learning the warning signals, what they mean, and how to localize them.� Each worker could go through a brief acclimation session with any hearing protector they are supplied with, and learn to recognize and localize the sounds they will encounter in the actual workplace.� With fairly simple injection of relevant warning signals into the system software, and calibration of these signals acoustically, the training system can easily be adapted for specific workplaces with relevant warning signals as well as ambient sound.� Thus, industrial and construction workers, prior to being placed on the job, can become well-informed on the auditory signals to which they must be vigilant, and learn how to localize those signals.� Also, the training system can assist in the industrial hygienist's selection of proper hearing protectors that best facilitate the detection and localization of specific industry warning signals such that situation awareness on the part of the worker can be maintained.

REFERENCES:

1. Casali, J. G. and Lee K. (2016) �Objective metric-based assessments for efficient evaluation of Auditory Situation Awareness Characteristic of TCAPS and HPDs, Final Report�. Contract #W81XWH-13-C-0193, Department of Defense, Hearing Center of Excellence, January 14, 2016. (95 pages) (DoD contractor�s report.) http://www.dtic.mil/docs/citations/AD1017344

2. Talcott, K. A., Casali, J. G., Keady, J. P. and Killion, M. C. (2012) �Azimuthal auditory localization of gunshots in a realistic field environment:� Effects of open-ear versus hearing protection-enhancement devices (HPEDS), military vehicle noise, and hearing impairment.� International Journal of Audiology, 51, S20-S30.

3. Clasing, J. E. and Casali, J. G. (2014) �Warfighter auditory situation awareness:� Effects of augmented hearing protection/enhancement devices and TCAPS for military ground combat applications.� International Journal of Audiology, 52, Suppl 2, S43-52.

4. Scharine, A., Letowski, T., and Sampson, J. B. (2009). �Auditory situation awareness in urban operations.� Journal of Military and Strategic Studies,11(4).

5. Casali, J. G. and Robinette, M. B. (2015) �Effects of user training with electronically-modulated sound transmission hearing protectors and the open ear on horizontal localization ability.� International Journal of Audiology, 54, Suppl 1, S37-45.

6. Fluitt, K., Gaston, J., Karna, V., and Letowski, T. (2010). �Feasibility of audio training for identification of auditory signatures of small arms fire (No. ARL-TR-5413).� Army Research Lab Aberdeen Proving Ground MD, Human Research and Engineering Directorate.

KEYWORDS: Situation Awareness; Auditory; Training; Measurement