Normative Ranges for Oculomotor and Reaction Time Tests in U.S. Military Service Members and Veterans.

Background:  Oculomotor and reaction time tests are frequently used assessments of vestibular symptoms, traumatic brain injury (TBI), or other neurological disorders in both clinical and research contexts. When interpreting these tests it is important to have a reference interval (RI) as a comparison for what constitutes a typical/expected response; however, the current body of research has only limited information regarding normative ranges calculated according to established standards or for a military-specific sample.

Purpose:  The purpose of the present study was to describe RIs for oculomotor and reaction time tests in a cohort of service members and veterans (SMVs) for use as comparators by clinicians and scientists.

The effects of extended-wear hearing aids on the localization accuracy of listeners with normal audiometric thresholds.

Extended-wear hearing aids (EWHAs) are small broadband analog amplification devices placed deeply enough in the ear canal to preserve most of the cues in the head-related transfer function. However, little is known about how EWHAs affect localization accuracy for normal hearing threshold (NHT) listeners. In this study, eight NHT participants were fitted with EWHAs and localized broadband sounds of different durations (250 ms and 4 s) and stimulus intensities (40, 50, 60, 70, and 80 dBA) in a spherical speaker array.

Transducer Variability in Speech-in-Noise Testing: Considerations Related to Stimulus Bandwidth.

Purpose: Clinical audiologists typically assume that headphones and insert phones will produce comparable results when they are used to conduct speech-in-noise or other audiological tests; however, this may not always be the case. Here, we show that there are significant differences in the scores that previous studies have reported for headphone and insert-phone transducers on the Words-in-Noise (WIN) Test, and discuss the possibility that the variations in high-frequency output that are allowable under the speech source specifications of American National Standards Institute S3.6 might be contributing to transducer-dependent differences in performance for the WIN and other tests that are presented through the auxiliary input channels of clinical audiometers.

Intelligibility of Natively and Nonnatively Produced English Speech Presented in Noise to a Large Cohort of United States Service Members.

Purpose: A corpus of English matrix sentences produced by 60 native and nonnative speakers of English was developed as part of a multinational coalition task group. This corpus was tested on a large cohort of U.S.

Age Impacts Speech-in-Noise Recognition Differently for Nonnative and Native Listeners.

Purpose: The purpose of this study was to explore potential differences in suprathreshold auditory function among native and nonnative speakers of English as a function of age.

Method: Retrospective analyses were performed on three large data sets containing suprathreshold auditory tests completed by 5,572 participants who were self-identified native and nonnative speakers of English between the ages of 18-65 years, including a binaural tone detection test, a digit identification test, and a sentence recognition test.

Results: The analyses show a significant interaction between increasing age and participant group on tests involving speech-based stimuli (digit strings, sentences) but not on the binaural tone detection test.

Examining the Use and Benefits of Low-/Mild-Gain Hearing Aids in Service Members with Normal Hearing Thresholds and Self-Reported Hearing Difficulties.

Low- (or mild-) gain hearing aids (LGHAs) are increasingly considered for individuals with normal peripheral hearing but significant self-reported hearing difficulties (SHDs). This study assesses the benefits of LGHAs as a management option for individuals with normal hearing thresholds (NHTs) and SHDs, comparing LGHA use and benefit to individuals with non-significant hearing difficulties (NHDs) and those with peripheral hearing loss. Questionnaires addressing hearing aid usage, benefit, hearing difficulties, and tinnitus were administered to 186 individuals who self-identified as hearing aid users in a sample of 6652 service members who were receiving their annual hearing tests.

Acute Hearing Deficits associated with Weapons Exposure in Section 734 Blast Overpressure Study (BOS).

Introduction: This prospective, multi-site, observational study describes ongoing efforts in support of the Fiscal Year 2018 National Defense Authorization Act (NDAA) Section 734 Blast Overpressure Study (BOS) to identify the acute effects impulse and blast exposure have on hearing abilities of the Warfighter in various military training environments.

Materials And Methods: Hearing thresholds, a binaural tone detection task, and auditory symptoms were collected before and immediately following weapons exposure across nine military training environments from January 2020 to October 2022. An additional 25 non-exposed control participants also completed the behavioral test battery.

Recommendations for a Military Health System Auditory Blast Injury Prevention Standard.

Introduction: Although existing auditory injury prevention standards benefit warfighters, the Department of Defense could do more to understand and address auditory injuries (e.g., hearing loss, tinnitus, and central processing deficits) among service members.

Functional Hearing Difficulties in Blast-Exposed Service Members With Normal to Near-Normal Hearing Thresholds.

Objectives: Estimated prevalence of functional hearing and communication deficits (FHCDs), characterized by abnormally low speech recognition and binaural tone detection in noise or an abnormally high degree of self-perceived hearing difficulties, dramatically increases in active-duty service members (SMs) who have hearing thresholds slightly above the normal range and self-report to have been close to an explosive blast. Knowing the exact nature of the underlying auditory-processing deficits that contribute to FHCD would not only provide a better characterization of the effects of blast exposure on the human auditory system, but also allow clinicians to prescribe appropriate therapies to treat or manage patient complaints.

Design: Two groups of SMs were initially recruited: (1) a control group (N = 78) with auditory thresholds ≤20 dB HL between 250 and 8000 Hz, no history of blast exposure, and who passed a short FHCD screener, and (2) a group of blast-exposed SMs (N = 26) with normal to near-normal auditory thresholds between 250 and 4000 Hz, and who failed the FHCD screener (cutoffs based on the study by Grant et al.

Prevalence of Self-Reported Voice Concerns and Associated Risk Markers in a Nonclinical Sample of Military Service Members.

Introduction: Difficult communication environments are common in military settings, and effective voice use can be critical to mission success. This study aimed to estimate the prevalence of self-reported voice disorders among U.S.

The Effect of Sound Localization on Auditory-Only and Audiovisual Speech Recognition in a Simulated Multitalker Environment.

Information regarding sound-source spatial location provides several speech-perception benefits, including auditory spatial cues for perceptual talker separation and localization cues to face the talker to obtain visual speech information. These benefits have typically been examined separately. A real-time processing algorithm for sound-localization degradation (LocDeg) was used to investigate how spatial-hearing benefits interact in a multitalker environment.

Short-term retention of learning after rapid adaptation to native and non-native speecha).

Non-native, accented speech spoken by unfamiliar talkers can be challenging to recognize, but rapid improvements in perception are often observed after a short period of exposure. However, it is not clear whether these improvements are retained over multiple sessions. Stimulus variability facilitates learning for non-native speech, so it is possible it may also induce increased retention of learning for speech produced with an unfamiliar accent.

An Emotion-Driven Vocal Biomarker-Based PTSD Screening Tool.

This paper introduces an automated post-traumatic stress disorder (PTSD) screening tool that could potentially be used as a self-assessment or inserted into routine medical visits to aid in PTSD diagnosis and treatment. With an emotion estimation algorithm providing arousal (excited to calm) and valence (pleasure to displeasure) levels through discourse, we select regions of the acoustic signal that are most salient for PTSD detection. Our algorithm was tested on a subset of data from the DVBIC-TBICoE TBI Study, which contains PTSD Check List Civilian (PCL-C) assessment scores.

Normative Ranges for, and Interrater Reliability of, Rotational Vestibular and Balance Tests in U.S. Military Service Members and Veterans.

Purpose: The objectives of this study were to (a) describe normative ranges-expressed as reference intervals (RIs)-for vestibular and balance function tests in a cohort of Service Members and Veterans (SMVs) and (b) to describe the interrater reliability of these tests.

Method: As part of the Defense and Veterans Brain Injury Center (DVBIC)/Traumatic Brain Injury Center of Excellence 15-year Longitudinal Traumatic Brain Injury (TBI) Study, participants completed the following: vestibulo-ocular reflex suppression, visual-vestibular enhancement, subjective visual vertical, subjective visual horizontal, sinusoidal harmonic acceleration, the computerized rotational head impulse test (crHIT), and the sensory organization test. RIs were calculated using nonparametric methods and interrater reliability was assessed using intraclass correlation coefficients between three audiologists who independently reviewed and cleaned the data.

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

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 (MRT 80 and MRT 160 ).

Design: Approximately 2400 SMs with various levels of hearing loss were recruited to complete the MRT 80 in conjunction with their annual hearing conservation evaluations.

Digital sampling of acoustic impulse noise: Implications for exposure measurement and damage risk criteria.

Current standards for the measurement of impulse noise (e.g., MIL-STD-1474E) recommend using a sampling rate of at least 200 kHz in order to accurately estimate the risk of hearing damage.

Using a boothless audiometer to estimate personal attenuation rating in a military hearing conservation clinic.

Hearing protection device (HPD) fit-testing is considered "best practice" for hearing conservation programs in the military. Yet many hearing conservation personnel do not have access to dedicated fit-test equipment. In this study, estimates of personal attenuation rating (PAR) obtained with a boothless audiometer are compared to those obtained with a field-microphone in a real ear (F-MIRE) system.

Development and Evaluation of a Body-Worn Dosimeter for Continuous and Impulsive Noise.

Noise exposure is encountered nearly everyday in both recreational and occupational settings, and can lead to a number of health concerns including hearing-loss, tinnitus, social-isolation and possibly dementia. Although guidelines exist to protect workers from noise, it remains a challenge to accurately quantify the noise exposure experienced by an individual due to the complexity and non-stationarity of noise sources. This is especially true for impulsive noise sources, such as weapons fire and industrial impact noise which are difficult to quantify due to technical challenges relating to sensor design and size, weight and power requirements.

Effects of better-ear glimpsing, binaural unmasking, and spectral resolution on spatial release from masking in cochlear-implant users.

Bilateral cochlear-implant (BICI) listeners obtain less spatial release from masking (SRM; speech-recognition improvement for spatially separated vs co-located conditions) than normal-hearing (NH) listeners, especially for symmetrically placed maskers that produce similar long-term target-to-masker ratios at the two ears. Two experiments examined possible causes of this deficit, including limited better-ear glimpsing (using speech information from the more advantageous ear in each time-frequency unit), limited binaural unmasking (using interaural differences to improve signal-in-noise detection), or limited spectral resolution. Listeners had NH (presented with unprocessed or vocoded stimuli) or BICIs.

Reference equivalent threshold sound pressure levels for the Wireless Automated Hearing Test System.

This paper presents reference equivalent threshold sound pressure levels (RETSPLs) for the Wireless Automated Hearing Test System (WAHTS), a recently commercialized device developed for use as a boothless audiometer. Two initial studies were conducted following the ISO 389-9 standard [ISO 389-9 (2009). "Acoustics-Reference zero for the calibration of audiometric equipment.

Assessment methods for determining small changes in hearing performance over time.

Although the behavioral pure-tone threshold audiogram is considered the gold standard for quantifying hearing loss, assessment of speech understanding, especially in noise, is more relevant to quality of life but is only partly related to the audiogram. Metrics of speech understanding in noise are therefore an attractive target for assessing hearing over time. However, speech-in-noise assessments have more potential sources of variability than pure-tone threshold measures, making it a challenge to obtain results reliable enough to detect small changes in performance.

Field assessment of acute auditory responses to environmental exposures in close quarters tactics training.

Objective: The purpose of this study was to evaluate auditory performance of military instructors as part of a training course involving noise and blast exposure. Boothless audiometry was used to estimate the test-retest reliability of the auditory measures under realistic field conditions and to determine risk of acute auditory injury during standard training practices.

Design And Study Sample: Thirteen U.

The cafeteria study: Effects of facial masks, hearing protection, and real-world noise on speech recognition.

The objective of this study was to evaluate the impact of wearing various types of personal protective equipment on speech recognition in a real-world, noisy listening environment. Groups of four young, normal-hearing adults participated in a live version of the Modified Rhyme Test in a noisy public cafeteria with and without the use of a non-medical disposable facial mask or combat earplugs in two different modes. Speech recognition, response time, and subjective difficulty were measured per individual.

Single-Sided Deafness Cochlear Implant Sound-Localization Behavior With Multiple Concurrent Sources.

Objectives: For listeners with one deaf ear and the other ear with normal/near-normal hearing (single-sided deafness [SSD]) or moderate hearing loss (asymmetric hearing loss), cochlear implants (CIs) can improve speech understanding in noise and sound-source localization. Previous SSD-CI localization studies have used a single source with artificial sounds such as clicks or random noise. While this approach provides insights regarding the auditory cues that facilitate localization, it does not capture the complex nature of localization behavior in real-world environments.