A Pilot Study to Evaluate a Residual Inhibition Technique in Hearing Aids for Suppression of Tinnitus.

Tinnitus acoustic therapy is defined as any use of sound where the intent is to alter the tinnitus perception and/or the reactions to tinnitus in a clinically beneficial way. The parameters of sound that may cause beneficial effects, however, are currently only theorized with limited data supporting their effectiveness. Residual inhibition is the temporary suppression or elimination of tinnitus that is usually observed following appropriate auditory stimulation. Our pilot study investigated the effects of a therapeutic acoustic stimulus that was individually customized to maximize residual inhibition of tinnitus and extend its duration to determine if there could be a sustained suppression of the tinnitus signal (i.e., reduced tinnitus loudness) and a reduction in the psychological and emotional reactions to tinnitus. This pilot study had two objectives: (1) to evaluate the feasibility of residual inhibition technique therapy through daily use of hearing aids and (2) to determine its effects by measuring reactionary changes in tinnitus with the Tinnitus Functional Index (TFI) and perceptual changes in tinnitus loudness. A total of 20 adults (14 males, 6 females; mean age: 58 years, SD = 12.88) with chronic tinnitus were enrolled in a four-visit study that consisted of the following: (1) baseline visit and initiation of the intervention period, (2) a 1-month postintervention visit, (3) 2-month postintervention visit and initiation of a wash-out period, and (4) a 3-month visit to assess the wash-out period and any lasting effects of the intervention. The intervention consisted of fitting bilateral hearing aids and creating an individualized residual inhibition stimulus that was streamed via Bluetooth from a smartphone application to the hearing aids. The participants were instructed to wear the hearing aids and stream the residual inhibition stimulus all waking hours for the 2-month intervention period. During the wash-out period, the participants were instructed to use the hearing aids for amplification, but the residual inhibition stimulus was discontinued. At all visits, the participants completed the TFI, study-specific self-report measures to document perceptions of tinnitus, a psychoacoustic test battery consisting of tinnitus loudness and pitch matching, and a residual inhibition test battery consisting of minimum masking and minimum residual inhibition levels. At the end of the trial, participants were interviewed about the study experience and acceptability of the residual inhibition treatment technique. Repeated measures analyses of variance (ANOVA) were conducted on the two main outcomes (TFI total score and tinnitus loudness) across all four visits. The results showed a significant main effect of visit on the TFI total score ( p < 0.0001). Specifically, the results indicated a significant reduction in TFI total scores from baseline to the 1-month post-intervention period, which remained stable across the 2-month post-intervention period and the wash-out period. The ANOVA results did not show a significant change in tinnitus loudness as a function of visit ( p = 0.480). The majority of the participants reported a positive experience with the study intervention at their exit interview. This pilot study demonstrated that residual inhibition as a sound therapy for tinnitus, specifically through the daily use of hearing aids, was feasible and acceptable to individuals suffering from chronic tinnitus. In addition, participants showed improvement in reactions to tinnitus as demonstrated by sustained reduction in TFI scores on average over the course of the treatment period. Achieving residual inhibition may also provide patients a feeling of control over their tinnitus, and this may have a synergistic effect in reducing the psychological and emotional distress associated with tinnitus. There was no significant reduction in long-term tinnitus loudness resulting from the residual inhibition treatment; however, the current pilot study may not have had sufficient power to detect such a change. The combination of tinnitus suppression and improved psychosocial/emotional reactions to tinnitus may result in a better quality of life in both the short and long term. A larger-scale study is needed to determine the validity of using residual inhibition as a clinical therapy option and to ascertain any effects on both perception and reactions to tinnitus.

Increasing Hearing Readiness Using Boothless Audiometry.

INTRODUCTION: U.S. Army regulations require all soldiers to undergo annual audiometric testing to maintain hearing readiness. The standard method of monitoring hearing in the DoD is via multi-person testing in sound-treated booths using the Defense Occupational and Environmental Health Readiness System-Hearing Conservation. COVID-19 significantly hindered the standard method, resulting in alarming declines in hearing readiness. In response, the Army Hearing Program initiated a pilot program to use boothless audiometers to supplement standard methods to increase hearing readiness. MATERIALS AND METHODS: Funding from the Coronavirus Aid, Relief, and Economic Security Act was used to purchase 169 boothless audiometers and increase staffing at dozens of Army Hearing Program clinics. Standard operating procedures were established for audiometric testing outside the booth using a process matching standard test parameters (i.e., test frequencies, tone characteristics, and interstimulus intervals). Additional capabilities developed to leverage this new technology during the annual hearing exam include the administration of automated contralateral masking, enhanced tinnitus screening, and hearing health education and training. RESULTS: Monitoring audiometry using boothless audiometers has been conducted for nearly 12,000 service members worldwide. Thresholds obtained via boothless audiometers are comparable to follow-up thresholds obtained from the standard test methods in the booth (mean difference 95% CI, -1.2, 0.9), and hearing readiness has returned to pre-pandemic levels at installations where this novel technology is being used regularly. CONCLUSIONS: Significant reductions in patient encounters as a direct result of the COVID-19 pandemic have led to innovative solutions leveraging boothless audiometers. While this has aided the primary mission to maintain a medically ready force, innovations from this endeavor highlight several additional improvements relative to current standards of care that should be considered for permanent inclusion in DoD Hearing Conservation Programs.

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. A boothless audiometer was used to measure hearing ability in the field. Sound level meters were attached on-body to record the exposure environment throughout training. RESULTS: Mean threshold change for the blast-exposed group was worse than the control group. Of the 188 blast-exposed participants, 23 experienced a temporary threshold shift (TTS) acutely after exposure. A decrease in binaural tone detection performance and increased symptom severity was found when comparing blast-exposed participants with a TTS versus those without a significant change in hearing. A complex but consistent relationship between measured exposure level (LAeq8hr) and the magnitude of the resulting TTS is suggested in the available data. CONCLUSIONS: Recent discussions on Section 734 studies examining the effects of repetitive blast exposure have indicated that hearing-related issues were a critical problem that needed additional research. Study outcomes provide highly repeatable results across various weapons systems with hazardous blast exposure. This standardized set of hearing assessment tools for evaluating acute effects of noise under field conditions has been critically important in improving our understanding of TTS in prospective human subject research.

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.S. Marine instructors participated in study activities. An audiologic testing suite embedded in a noise-attenuating headset was used to test various tone detection tasks on subjects after exposure. Acoustic exposures were captured with sound level meters. RESULTS: Boothless audiometry provide highly repeatable results for various tests of auditory performance in the field environment. In this test population, changes in auditory performance pre- and post-noise exposure were minimal for most measures. The notable exception was binaural (NoSπ) tone detection, which showed significant degradations both as a function of pre- and post-noise exposure on the same day and as a result of cumulative noise exposure over the period of the study. CONCLUSIONS: Study outcomes are consistent with prior laboratory and epidemiological work and suggest a link between the binaural processes required for NoSπ detection and the hearing-related issues reported by blast-exposed service members.

Methodology of the INVestigating traIning assoCiated blasT pAthology (INVICTA) study.

BACKGROUND: Subconcussive blast exposure during military training has been the subject of both anecdotal concerns and reports in the medical literature, but prior studies have often been small and have used inconsistent methods. METHODS: This paper presents the methodology employed in INVestigating traIning assoCiated blasT pAthology (INVICTA) to assess a wide range of aspects of brain function, including immediate and delayed recall, gait and balance, audiologic and oculomotor function, cerebral blood flow, brain electrical activity and neuroimaging and blood biomarkers. RESULTS: A number of the methods employed in INVICTA are relatively easy to reproducibly utilize, and can be completed efficiently, while other measures require greater technical expertise, take longer to complete, or may have logistical challenges. CONCLUSIONS: This presentation of methods used to assess the impact of blast exposure on the brain is intended to facilitate greater uniformity of data collection in this setting, which would enable comparison between different types of blast exposure and environmental circumstances, as well as to facilitate meta-analyses and syntheses across studies.

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. Results suggest that boothless audiometers can be used to make accurate PAR estimates. The ability to perform HPD fit-testing with multipurpose boothless audiometers has the potential to greatly expand the accessibility of earplug verification and ultimately to improve the effectiveness of hearing conservation programs.

The Effect of Using an Active Earmuff on High Frequency Hearing in United States Marine Corps Weapons Instructors.

OBJECTIVES: To investigate the change in hearing and perceived comfort over 1 year related to using an active hearing protection device (HPD) among United States Marine Corps (USMC) personnel routinely exposed to hazardous noise. METHODS: USMC Weapons Instructors (n = 127) were issued an active earmuff that met military standards and was compatible with other protective equipment. These participants completed pre- and post-hearing tests and comfort surveys. A control cohort (n = 94) was also included to compare individual changes in high-frequency pure tone average (HF-PTA) over 1 year. RESULTS: The control group's HF-PTA was 3 dB worse than the intervention group after only 1 year. Survey responses revealed perceived improvements in the ability to hear and understand, situational awareness, and safety. CONCLUSIONS: Active HPDs can reduce hearing loss and improve hearing-related occupational tasks.