Development and Human Factors Evaluation of a Portable Auditory Localization Training System.

OBJECTIVE: To design and develop a Portable Auditory Localization Acclimation Training (PALAT) system capable of producing psychoacoustically accurate localization cues; evaluate the training effect against a proven full-scale, laboratory-grade system under three listening conditions; and determine if the PALAT system is sensitive to differences among electronic level-dependent hearing protection devices (HPDs). BACKGROUND: In-laboratory auditory localization training has demonstrated the ability to improve localization performance with the open (natural) ear, that is, unoccluded, and while wearing HPDs. The military requires a portable system capable of imparting similar training benefits as those demonstrated in laboratory experiments. METHOD: In a full-factorial repeated measures design experiment, 12 audiometrically normal participants completed localization training and testing using an identical, optimized training protocol on two training systems under three listening conditions (open ear, TEP-100, and ComTac™ III). Statistical tests were performed on mean absolute accuracy score and front-back reversal errors. RESULTS: No statistical difference existed between the PALAT and laboratory-grade DRILCOM systems on two dependent localization accuracy measurements at all stages of training. In addition, the PALAT system detected the same localization performance differences among the three listening conditions. CONCLUSION: The PALAT system imparted similar training benefits as the DRILCOM system and was sensitive to HPD localization performance differences. APPLICATION: The user-operable PALAT system and optimized training protocol can be employed by the military, law enforcement, and various industries, to improve auditory localization performance in conditions where auditory situation awareness is critical to safety.

Aircrew Performance and Safety While Using Protective Masks in Response to Coronavirus Disease.

INTRODUCTION: In response to the urgent need for safe aircrew respiratory protection due to the COVID-19 pandemic, three small descriptive evaluations were conducted with aircrew and air traffic controllers (ATC) that assessed the impact of mask use on safety and performance onboard rotary wing aircraft.METHODS: A series of evaluations assessed aircrew performance using the 3MTM Model 1860 N95 respiratory protection mask, two aviation-specific cloth mask prototypes, and a commercial off-the-shelf aviation-specific cloth mask. The series of evaluations included different sets of subjects consisting of up to five Black Hawk helicopter aircrew members, air traffic control (ATC), and 12 CH-47 aircrew members. The Modified Rhyme Test was used to measure speech intelligibility and was administered in the UH-60 among crewmembers of the same aircraft, between pilots of different aircraft, and between the pilots and ATC. Measures of workload, usability, comfort, and pulse oximetry were also administered.RESULTS: Results from the Modified Rhyme Test indicated that all subjects scored greater than 80% accuracy given the proper microphone positioning relative to the mask. With respect to workload, NASA-TLX total scores for the perform radio communications task was 50.83.DISCUSSION: Despite an elevated perceived degree of workload on the communications flight task, results from the speech intelligibility test indicated that performance was maintained within the acceptable range as defined by MIL-STD-1474E, Design Criteria Standard Noise Limit. This abbreviated evaluation suggests that the face masks tested are safe for use by helicopter aircrew under the conditions tested.Cave KM, Kelley AM, Feltman KA, Gerstner JA, Stewart JL, Crowley JS. Aircrew performance and safety while using protective masks in response to coronavirus disease. Aerosp Med Hum Perform. 2021; 92(4):274280.

Optimisation of an auditory azimuth localisation training protocol for military service members.

Objective: Design an optimised auditory azimuth localisation training protocol by: (1) differing the number of training stimuli presentations to determine the highest angular accuracy achieved in the fewest training sessions, (2) evaluating the presence of training transfer from a broadband stimulus to untrained military-relevant stimuli and (3) measuring the effect of differing training strategies on localisation accuracy.Design: Two pilot studies of 18 and six subjects, respectively, determined the number of presentations and type of stimuli to be included in a localisation training experiment that evaluated different training strategies. In the pilot studies, participants trained using eight Learning Units (LU) and then tested using untrained stimuli. In the main experiment, 40 participants completed eight LUs using four different learning strategies, with 10 participants randomly assigned to each condition.Sample: All participants were ages 18-42 normal-hearing listeners with thresholds not exceeding 25 dB HL and asymmetry not exceeding 15 dB HL.Results: Transfer of training occurred using three of the four untrained stimuli. The training strategy that resulted in the highest localisation accuracy involved active participation.Conclusions: Training with a broadband stimulus transfers to untrained broadband stimuli. Training involving the active participation strategy resulted in the greatest localisation accuracy.

Blast injury of the ear: clinical update from the global war on terror.

The purpose of this study was to describe the effects of blast exposure on hearing status. This study retrospectively analyzed hearing thresholds and otologic complaints for >250 patients with blast-related injuries from the global war on terror. Of patients who received full diagnostic evaluations, 32% reported a history of tympanic membrane perforation, 49% experienced tinnitus, 26% reported otalgia (ear pain), and 15% reported dizziness. Expected hearing thresholds were computed by applying age-correction factors to hearing tests performed earlier in the service members' careers and before their most recent deployment. Expected hearing thresholds were significantly better than actual postdeployment thresholds, indicating that significant changes occurred in the patients' hearing that could not be accounted for by age. Results from this study underline the need for documentation of pre-and postdeployment hearing tests and prompt otologic evaluation for the blast-exposed population.