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.

Benefits of Nonlinear Frequency Compression in Adult Hearing Aid Users

Background: Frequency-lowering (FL) algorithms are an alternative method of providing access to high-frequency speech cues. There is currently a lack of independent research addressing: (1) what functional, measureable benefits FL provides; (2) which, if any, FL algorithm provides the maximum benefit, (3) how to clinically program algorithms, and (4) how to verify algorithm settings. Purpose: Two experiments were included in this study. The purpose of Experiment 1 was to (1) determine if a commercially available nonlinear frequency compression (NLFC) algorithm provides benefit as measured by improved speech recognition in noise when fit and verified using standard clinical procedures; and (2) evaluate the impact of acclimatization. The purpose of Experiment 2 was to (1) evaluate the benefit of using enhanced verification procedures to systematically determine the optimal application of a prototype NLFC algorithm, and (2) determine if the optimized prototype NLFC settings provide benefit as measured by improved speech recognition in quiet and in noise. Research Design: A single-blind, within-participant repeated measures design in which participants served as their own controls. Study Sample: Experiment 1 included 26 participants with a mean age of 68.3 yr and Experiment 2 included 37 participants with a mean age of 68.8 yr. Participants were recruited from the Audiology and Speech Pathology Center at Walter Reed National Military Medical Center in Bethesda, MD. Intervention: Participants in Experiment 1 wore bilateral commercially available hearing aids fit using standard clinical procedures and clinician expertise. Participants in Experiment 2 wore a single prototype hearing aid for which FL settings were systematically examined to determine the optimum application. In each experiment, FL-On versus FL-Off settings were examined in a variety of listening situations to determine benefit and possible implications. Data Collection and Analysis: In Experiment 1, speech recognition measures using the QuickSIN and Modified Rhyme Test stimuli were obtained at initial bilateral fitting and 3–5 weeks later during a follow-up visit. In Experiment 2, Modified Rhyme Test, /s/, /∫/ consonant discrimination task, and dual-task cognitive load speech recognition performance measures were conducted. Participants in Experiment 2 received four different systematic hearing aid programs during an initial visit and speech recognition data were collected over 2–3 follow-up sessions. Results: Some adults with hearing loss obtained small-to-moderate benefits from implementation of FL, while others maintained performance without detriment in both experiments. There was no significant difference among FL-On settings systematically obtained in Experiment 2. There was a modest but significant age effect in listeners of both experiments that indicated older listeners (>65 yr) might benefit more on average from FL than younger listeners. In addition, there were reliable improvements in the intelligibility of the phonemes /η/ and /b/ for both groups, and /ð/ for older listeners from the FL in both experiments. Conclusions: Although the optimum settings, application, and benefits of FL remain unclear at this time, there does not seem to be degradation in listener performance when FL is activated. The benefits of FL should be explored in older adult (>65 yr) listeners, as they tended to benefit more from FL applications.