Developing an Evidence-Based Military Auditory Fitness-for-Duty Standard Based on the 80-Word Modified Rhyme Test

Abstract

Objectives: One important function of military audiology is to conduct evaluations of service members (SMs) with hearing loss to ensure they are fit for deployment in dangerous operational environments. The objective of this study was to establish evidence-based auditory fitness-for-duty criteria based on speech-in-noise performance on the 80- and 160-word clinical versions of the Modified Rhyme Test (MRT80 and MRT160). Design: Approximately 2400 SMs with various levels of hearing loss were recruited to complete the MRT80 in conjunction with their annual hearing conservation evaluations. These SMs were also asked to perform one or more operationally-relevant listening tasks based on audio recordings made in highly realistic military training environments. The scores on these tests were compared to determine how well a proposed cutoff criterion for the MRT80 was able to identify individuals who are hard of hearing with an exceptionally high risk of abnormally poor performance on operationally-relevant hearing tasks. Results: The results show that a cutoff criterion that combines the percent correct score on two lists of the MRT80 (i.e. MRT160) with information about the better-ear threshold at 2 kHz is generally able to separate listeners with hearing loss into those who are likely to perform relatively well on operational listening tests and those who are likely to perform poorly on these tasks. This is consistent with current military acquisition standards, which identify the MRT as the preferred test for evaluating speech intelligibility for radios, headsets, and other communication equipment. It is also consistent with prior studies conducted in high-fidelity military simulations which have shown a significant correlation between MRT performance and operational outcomes. Conclusions: The proposed selection criteria, along with the new hearing profile standards that were recently adopted by the US Army, appear to provide an effective evidence-based methodology for identifying those SMs with hearing loss who are most at risk for poor performance on hearing-critical military tasks.

Current age and language use impact speech-in-noise differently for monolingual and bilingual adults

“…Participants included in this study were recruited as part of a larger research study examining suprathreshold auditory function in US SMs, in which participants answer survey questions and complete auditory tasks such as speech recognition in noise (Brungart et al, 2023;Davidson et al, 2023). A total of 3836 United States SMs (546 female, 3290 male) between the ages of 18-57 years (mean (SD) = 28.4 (7.28)) were recruited for this study.…”

“…In the Army, the fitness-for-duty testing is based on the MRT160, which is a slightly different version of the MRT test used in this study. The MRT is the standard test in the military for evaluating communication systems, and previous research has shown that performance on the MRT is correlated with the ability to understand operationally-relevant speech signals (Brungart et al, 2023) and to perform militarily relevant tasks (Garinther et al, 1995).…”

Perforated Concave Earplug (pCEP): A Proof-of-Concept Earplug to Improve Sound Localization without Compromising Noise Attenuation

“…One end of the "listen only" acoustic tube is connected to the narrow opening (6) using a simple passive adaptor (see Figure S1), while the other end is connected to the audio output of a voice tactical radio, for example, a personalized networking radio such as Elbit Systems-Land and C 4 ™ PNR-1000™. The second component added within tube (4) is a small noise filter (7) used to provide further sound attenuation before passing through narrow tube (3). Such a small noise filter was suggested by Berger and Hamery [23] to change sound attenuation behavior as is the case with the "Institute Saint Louis (ISL) filter" in the 3M™-Combat-Arms™4.1 earplug.…”

“…Such signals need to be heard clearly; hence, hearing acuity is a critical component of combat effectiveness and mission success [1,2]. In this context, Brungart et al [3] recently developed an evidence-based military auditory fitness-for-duty standard based on the 80-word modified rhyme test (MRT). This criterion was based on minimum speech intelligibility requirements that have been established for military communications equipment used by listeners with normal hearing.…”

Aging Impacts Speech-In-Noise Recognition Differently For Nonnative And Native Listeners

“…In the present study, we conduct a retrospective analysis of several datasets collected by our group that are well suited to examine potential interactions between aging and one dimension of linguistic experience: listeners' status as NNE or NE. Our group has conducted several large-scale studies of auditory function among United States Service Members (SMs; Brungart et al, 2019Brungart et al, , 2023K. W. Grant et al, 2021).…”