Douglas S. Brungart

Auditory gap detection thresholds are an important tool for evaluating temporal processing deficits in human listeners, but current tests are too cumbersome for widespread clinical use. This letter describes the development and validation of a rapid 18-trial test for assessing gap detection based on an earlier binaural tone-in-noise paradigm. Results from 616 normal-hearing listeners show psychometric properties similar to the clinical gaps-in-noise test and provide normative values that support preliminary use as a screener for temporal processing deficits in clinical populations.

Prior work shows that individuals who frequently experience symptoms following noise exposure have greater hearing complaints and worse tone-in-noise detection abilities even with “normal” audiometric thresholds. This study extends previous work by quantifying the impact of post-exposure hearing symptoms on speech-in-noise (SIN) detection. Intelligibility and response times were examined in two large samples of U.S. service members (SMs) who completed tablet-based questionnaires, pure-tone audiometry, and SIN tests based on the Modified Rhyme Test (MRT). In Experiment 1, 1551 SMs completed a version of the MRT based on the clinical MRT80. In Experiment 2, 4768 SMs completed an abbreviated MRT without carrier phrases. Participants were categorized based on hearing acuity and questionnaire responses. Mixed-effects models predicted MRT outcomes using better-ear four-frequency pure-tone average (PTA4), post-exposure hearing symptom history, and noise exposure as predictors. Both experiments showed effects of post-exposure symptom history and PTA4 on accuracy and response time. Overall, SMs with a history of post-exposure hearing symptoms exhibited deficits in SIN performance, even with normal audiometric thresholds. These findings suggest that symptoms consistent with temporary threshold shifts (TTS) may indicate underlying auditory damage, underscoring the importance of considering TTS in hearing conservation, clinical assessment, and research.

Purpose: This commentary discusses the evolving role of boothless audiometry in hearing conservation programs. It addresses space and access limitations of traditional booth-based testing and explores how boothless solutions offer alternatives for maintaining and boosting service delivery. Method: We present a conceptual discussion on the utility of boothless audiometry for hearing conservation monitoring, followed by a real-world implementation example from Department of Defense (DOD) hearing conservation clinics. Results: DOD hearing conservation programs completed over 40,000 boothless hearing tests between 2021 and May 2025, showing progressive year-over-year adoption. Patient satisfaction surveys from over 800 service members revealed positive ratings for boothless compared to traditional booth-based testing. Implementation feedback emphasized the importance of quiet testing environments and comprehensive staff training. Conclusions: Boothless audiometry represents a viable, and often underutilized, model for conducting audiometric monitoring for hearing conservation programs. Its portability, scalability, and adaptability make it particularly suited to outreach settings, resource-limited clinics, or as a contingency during facility disruptions. This commentary encourages audiologists to explore boothless approaches as complementary, not alternative, methods for increasing access to high-quality care.

Many commercially available hearing protector fit testing (HPFT) systems are able to measure personal attenuation rating (PAR) values for earplugs, but only a few are capable of measuring PAR with over-the-ear protectors and even fewer are able to estimate PAR values with double hearing protection. One approach that could potentially be used with any type of hearing protection is to modify the real-ear attenuation at threshold method to use an occluded threshold that is measured with circumaural headphones worn around the neck rather than over the ears. However, this method would only be valid if the neck-to-ear transfer function of the headphones is stable across a variety of headphone fittings. This study evaluated the validity of a neck-based HPFT approach by (1) measuring the transfer function from headphones worn around the neck to the ear across a variety of headphone positions and head and ear geometries; and (2) using an acoustic test fixture to compare PAR values measured with a neck-based sound source to those obtained with more conventional HPFT approaches. The results indicate that the neck-based HPFT system has a relatively consistent neck-to-ear transfer function and produced PAR values comparable to those obtained with other HPFT systems.

Objectives: Current hearing conservation standards assume that changes in the pure-tone audiogram fully capture the effects of noise-induced hearing damage. However, recent data suggest that individuals who frequently experience acute hearing symptoms after noise exposure may suffer long-term increases in hearing difficulty, even when their pure-tone thresholds remain unchanged. It is unclear whether these increases in subjective hearing difficulties correspond to objective measures of hearing ability. This study explores (1) whether tone-in-noise detection is negatively impacted by a history of noise-induced temporary threshold shifts, (2) whether noise exposure history or the number of temporary threshold shifts after exposure is the better predictor of tone-in-noise detection, and (3) whether tone-in-noise detection provides insights into subjective hearing complaints independent of the audiogram. Design: Two experiments were conducted to measure 500-Hz tone-in-noise detection thresholds among service members (SMs). Audiometric data were collected from SMs in addition to questionnaires about perceived hearing difficulties, noise exposure history, and history of hearing symptoms following noise exposure. In Experiment 1, 4253 SMs completed a 33-trial Masking Level Difference test that measured detection thresholds for a 500-Hz homophasic tone presented in homophasic noise (the N ₀ S ₀ condition) and a 500 Hz antiphasic tone presented in homophasic noise (the N ₀ S _π condition). In Experiment 2, 17,658 SMs completed an 18-trial test measuring N ₀ S _π detection. Results from Experiment 2 were converted into N ₀ S _π detection thresholds equivalent to those in Experiment 1 using data from 3206 SMs who completed both tests. Linear models were then fit to the data to determine the effects of noise exposure history, symptoms experienced after exposure, and pure-tone audiometric thresholds on N ₀ S ₀ and N ₀ S _π detection. Linear models were also used to determine the degree to which post-exposure symptoms, pure-tone audiometric thresholds, and N ₀ S _π detection could predict self-reported hearing complaints. Results: Individuals who reported frequent hearing symptoms after noise exposure had substantially worse N ₀ S ₀ and N ₀ S _π detection thresholds than those without these symptoms, even after controlling for pure-tone audiometric thresholds. Group differences were smallest for individuals who had good hearing thresholds and increased systematically as hearing thresholds increased within the normal range. Noise exposure history also influenced N ₀ S _π thresholds, but had a smaller effect than that of post-exposure symptoms. Finally, combining N ₀ S _π and hearing thresholds explained roughly 50% more of the variance in hearing complaint scores than either factor alone. Conclusions: These findings are consistent with results from animal models showing that temporary changes in hearing thresholds are associated with hearing damage. The results suggest that some listeners experience chronic hearing damage from the same noise exposures that have no effect on other listeners. Such auditory damage seems to impact subjective hearing difficulty, as reported previously, and objective tone-in-noise detection, as observed here. Evidence from this and other studies justifies the addition of questions regarding temporary threshold shift history and hearing complaints into all annual hearing tests conducted in hearing conservation programs. Adding a measure of binaural tone-in-noise detection to the clinical battery administered to noise-exposed patients who report hearing difficulties despite normal audiograms is also recommended.

Purpose: Numerous individuals in the United States are bothered enough by tinnitus that it affects normal daily activities, including sleep and concentration. There is a high prevalence of self-reported bothersome tinnitus in the U.S. military, and therefore, it is important to assess the impact of tinnitus on functional performance. The primary aim of this study was to examine the effects of tinnitus on a range of subjective, objective, auditory, and cognitive measures. A secondary aim was to determine which factors best predict whether individuals ever self-reported tinnitus. A prospective study was conducted to address the primary aim, and an exploratory machine learning approach was used to address the second. Method: The study included 463 active duty U.S. Service members being seen for annual hearing surveillance. Participants completed several auditory and cognitive tests, along with questionnaires regarding tinnitus, depression, anxiety, and sleep difficulty. Results: The primary aim found no significant performance differences on tasks of selective attention, short-term memory, or speech in noise between the tinnitus groups. However, there were significant group differences in extended high-frequency hearing. A machine learning algorithm was used to predict whether an individual self-reported experiencing tinnitus. The model had approximately 80% accuracy, excellent sensitivity, and modest specificity. Conclusions: Study findings corroborated other evidence that extended high-frequency thresholds are poorer in those who reported ever experiencing tinnitus, regardless of tinnitus bother. Our results suggest that combining results from audiometric testing, high-frequency hearing, and subjective assessment of sleep achieved 80% accuracy in predicting tinnitus presence.

Purpose: The purpose of this study was to determine the differences between self-reported hearing difficulties, response time, and blast exposure history for those with and without auditory processing deficits, which were classified based on abnormal results on behavioral speech-in-noise and binaural-processing assessments. The study also examined factors that contributed to low-gain hearing aid (LGHA) benefit. Method: Military service members were recruited for the research study. Participants were classified into three groups based on their performance on auditory processing tests: failing two tests (dual deficit [DualDef], n = 47), failing one test (single deficit [SingleDef], n = 207), and failing zero tests (Control, n = 5,046). All participants had normal hearing thresholds (NHTs) defined by ≤ 25 dB HL at frequencies 500–6000 Hz. Results: Participants who failed at least one auditory processing test (DualDef and SingleDef groups) reported significantly more hearing difficulties and had significantly slower response times than the Control group. The DualDef group also had significantly more hearing difficulties relative to the SingleDef group. More than half of the participants in the DualDef and SingleDef groups reported having blast exposure, compared to less than 40% in the control group. Participants who reported blast exposure also reported significantly better LGHA benefit compared to those who reported having no blast exposure. Conclusion: This study appears to validate the use of performance on behavioral listening tests to identify individuals who may be suffering from auditory processing deficits and might benefit from LGHAs, particularly when the symptoms are related to a history of blast exposure.

Purpose: Some bilinguals may exhibit lower performance when recognizing speech in noise (SiN) in their second language (L2) compared to monolinguals in their first language. Poorer performance has been found mostly for late bilinguals (L2 acquired after childhood) listening to sentences containing linguistic context and less so for simultaneous/early bilinguals (L2 acquired during childhood) and when testing context-free stimuli. However, most previous studies tested younger participants, meaning little is known about interactions with age; the purpose of this study was to address this gap. Method: Context-free SiN understanding was measured via the Modified Rhyme Test (MRT) in 3,803 young and middle-aged bilingual and monolingual adults (ages 18–57 years; 19.6% bilinguals, all L2 English) with normal to near-normal hearing. Bilingual adults included simultaneous ( n = 462), early ( n = 185), and late ( n = 97) bilinguals. Performance on the MRT was measured with both accuracy and response time. A self-reported measure of current English use was also collected for bilinguals to evaluate its impact on MRT performance. Results: Current age impacted MRT accuracy scores differently for each listener group. Relative to monolinguals, simultaneous and early bilinguals showed decreased performance with older age. Response times slowed with increasing current age at similar rates for all groups, despite faster overall response times for monolinguals. Among all bilingual listeners, greater current English language use predicted higher MRT accuracy. For simultaneous bilinguals, greater English use was associated with faster response times. Conclusions: SiN outcomes in bilingual adults are impacted by age at time of testing and by fixed features of their language history (i.e., age of acquisition) as well as language practices, which can shift over time (i.e., current language use). Results support routine querying of language history and use in the audiology clinic. Supplemental Material: https://doi.org/10.23641/asha.28405430

Purpose: Recent Department of Defense policy changes for hearing conservation programs mandate hearing protector fit testing (HPFT) for many noise-exposed populations. However, the implementation of this requirement across various clinical scenarios is not yet defined. This Quality Improvement (QI) study evaluated the efficacy of current educational procedures at a U.S. Marine Corps (USMC) accession point by performing HPFT before and after small-group training. Method: The QI study employed a pre- and postgroup design to evaluate the effectiveness of training. HPFT was conducted on 122 USMC recruits before and after small-group instruction during hearing conservation in-processing. A field microphone-in-real-ear system was used to calculate the personal attenuation rating for each participant. Additionally, 48 recruits returned for a 1-month follow-up to repeat the fit test procedure. Results: Small-group HPD training resulted in a mean personal attenuation rating improvement of 14.6 dB among a cohort of USMC recruits. One month after training, a decrease in PAR was observed, yet outcomes remained notably higher than baseline, indicating sustained training effectiveness. Conclusions: This study highlights the utility of small-group HPD training in improving immediate fit-test outcomes. Implementing these procedures at large-scale in-processing events, such as military accession points, should be considered a viable option. Future research should focus on long-term maintenance strategies, as sustaining these outcomes over time remains a challenge.