Melissa A. Papesh

Purpose: Clinical care for patients who report substantial hearing difficulties despite having little or no hearing loss is a topic of great debate within and beyond audiology. Building on our previous retrospective review of veterans evaluated for auditory processing disorders across the Veterans Health Administration (VHA), the current work presents five such case studies. The goal is to work toward improved patient care by providing a more in-depth view highlighting both strengths and weaknesses of approaches to care for veterans whose hearing difficulties are not explained by hearing loss. Method: Five case studies were selected for review with the goal of identifying individuals with a wide range of etiologies and experiences receiving care for auditory complaints across the VHA. All information provided is taken directly from chart notes available from VHA and Defense Health Agency sources. Results: Etiologies included traumatic brain injury, jet fuel exposure, and nonspecific origins. Some patients experienced well-coordinated care across medical departments, while others experienced repeated barriers and high burdens of self-advocacy while trying to navigate the health care system. Furthermore, differences in the approach of audiologists and speech-language pathologists are highlighted, including differing emphasis on diagnostic tests versus self-report measures and use of top-down versus bottom-up rehabilitation tools. Conclusion: This work highlights several options likely to improve care for veterans with auditory processing deficits, including greater emphasis on addressing patient-specific needs and goals, improved communication and collaboration between audiology and other medical disciplines, and the potential role for auditory device–based rehabilitation options, even among patients with minimal hearing loss.

Purpose: There is currently no consensus regarding an evidence-based assessment protocol for normal-hearing patients with a history of brain injury who report auditory difficulties. This work used a large test battery to identify measures that explained the most variability across participants with and without a history of head injury, to determine relationships between measures, and to explore patterns of performance across participants, with the aim of identifying measures that should be considered in future research on developing clinical assessment protocols for this unique patient population. Method: A principal component analysis was conducted on data from 22 self-report, central auditory processing, and cognitive processing measures completed by a sample of 95 participants. Participants included Veterans with a history of blast exposure, Veterans with a history of nonblast mild traumatic brain injury (mTBI), and a sample of control participants with no history of head injury. Results: Several central auditory processing and self-report measures explained variance in the data set. However, analyses revealed that performance on the behavioral auditory processing tests was not predictive of self-reported auditory and non-auditory symptom severity. A cluster analysis further revealed spread in performance across participants with a history of blast exposure or nonblast mTBI. Conclusions: Results from the current study underscore the need for a comprehensive, individualized approach to patient care for those with a history of head injury. The measures identified in the current analysis should be investigated in future studies that aim to develop an auditory assessment protocol for this patient population. Supplemental Material: https://doi.org/10.23641/asha.32060232

It has been established that blast exposure and brain injury can result in self-reported and measured auditory processing deficits in individuals with normal or near-normal hearing sensitivity. However, the impaired sensory and/or cognitive mechanisms underlying these auditory difficulties are largely unknown. This work used a combination of behavioral and electrophysiological measures to explore how neural stimulus discrimination and processing speed contribute to impaired temporal processing in blast-exposed Veterans measured using the behavioral Gaps-in-Noise (GIN) Test. Results confirm previous findings that blast exposure can impact performance on the GIN and effect neural auditory discrimination, as measured using the P3 auditory event-related potential. Furthermore, analyses revealed correlations between GIN thresholds, P3 responses, and a measure of behavioral reaction time. Overall, this work illustrates that behavioral responses to the GIN are dependent on both auditory-specific bottom-up processing beginning with the neural activation of the cochlea and auditory brainstem as well as contributions from complex neural networks involved in processing speed and task-dependent target detection.

Purpose: Approximately 23 million Americans might have functional hearing difficulties (FHDs) that are not well explained by their audiometric thresholds. Clinical management of patients with FHDs is the subject of considerable debate, with few evidence-based guidelines to direct patient care. A better understanding of the characteristics of patients who seek help for FHDs, as well as current audiological management practices, is needed to direct research efforts to the areas greatest opportunity for advancement of clinical care. Method: A retrospective chart review was conducted examining the medical records of a random sample of 100 Veterans who underwent auditory processing assessments across the VA Health Care System between 2008 and 2020. Results: Patients were young to middle-age, often with previous traumatic brain injury or blast exposure. Mental health, sleep, and pain disorders were common. No consistent relationships emerged between specific patient factors and domains of auditory processing deficits. Low-gain hearing aids were provided to 35 patients, 69% of whom continued wearing their hearing aids for at least 2 years. Conclusion: Future research should address the potential overlap in symptoms and treatment for comorbid health conditions and FHDs, as well as the conditions underlying successful hearing aid use in this patient population.

Anecdotal clinical reports and findings from recent research suggest that auditory symptoms are common following concussion. However, auditory symptoms are not

Purpose: A questionnaire survey was conducted to collect information from clinical audiologists about rehabilitation options for adult patients who report significant auditory difficulties despite having normal or near-normal hearing sensitivity. This work aimed to provide more information about what audiologists are currently doing in the clinic to manage auditory difficulties in this patient population and their views on the efficacy of recommended rehabilitation methods. Method: A questionnaire survey containing multiple-choice and open-ended questions was developed and disseminated online. Invitations to participate were delivered via e-mail listservs and through business cards provided at annual audiology conferences. All responses were anonymous at the time of data collection. Results: Responses were collected from 209 participants. The majority of participants reported seeing at least one normal-hearing patient per month who reported significant communication difficulties. However, few respondents indicated that their location had specific protocols for the treatment of these patients. Counseling was reported as the most frequent rehabilitation method, but results revealed that audiologists across various work settings are also successfully starting to fit patients with mild-gain hearing aids. Responses indicated that patient compliance with computer-based auditory training methods was regarded as low, with patients generally preferring device-based rehabilitation options. Conclusions: Results from this questionnaire survey strongly suggest that audiologists frequently see normal-hearing patients who report auditory difficulties, but that few clinicians are equipped with established protocols for diagnosis and management. While many feel that mild-gain hearing aids provide considerable benefit for these patients, very little research has been conducted to date to support the use of hearing aids or other rehabilitation options for this unique patient population. This study reveals the critical need for additional research to establish evidence-based practice guidelines that will empower clinicians to provide a high level of clinical care and effective rehabilitation strategies to these patients.

Objectives: Veterans who have been exposed to high-intensity blast waves frequently report persistent auditory difficulties such as problems with speech-in-noise (SIN) understanding, even when hearing sensitivity remains normal. However, these subjective reports have proven challenging to corroborate objectively. Here, we sought to determine whether use of complex stimuli and challenging signal contrasts in auditory evoked potential (AEP) paradigms rather than traditional use of simple stimuli and easy signal contrasts improved the ability of these measures to (1) distinguish between blast-exposed Veterans with auditory complaints and neurologically normal control participants, and (2) predict behavioral measures of SIN perception. Design: A total of 33 adults (aged 19–56 years) took part in this study, including 17 Veterans exposed to high-intensity blast waves within the past 10 years and 16 neurologically normal control participants matched for age and hearing status with the Veteran participants. All participants completed the following test measures: (1) a questionnaire probing perceived hearing abilities; (2) behavioral measures of SIN understanding including the BKB-SIN, the AzBio presented in 0 and +5 dB signal to noise ratios (SNRs), and a word-level consonant-vowel-consonant test presented at +5 dB SNR; and (3) electrophysiological tasks involving oddball paradigms in response to simple tones (500 Hz standard, 1000 Hz deviant) and complex speech syllables (/ba/ standard, /da/ deviant) presented in quiet and in four-talker speech babble at a SNR of +5 dB. Results: Blast-exposed Veterans reported significantly greater auditory difficulties compared to control participants. Behavioral performance on tests of SIN perception was generally, but not significantly, poorer among the groups. Latencies of P3 responses to tone signals were significantly longer among blast-exposed participants compared to control participants regardless of background condition, though responses to speech signals were similar across groups. For cortical AEPs, no significant interactions were found between group membership and either stimulus type or background. P3 amplitudes measured in response to signals in background babble accounted for 30.9% of the variance in subjective auditory reports. Behavioral SIN performance was best predicted by a combination of N1 and P2 responses to signals in quiet which accounted for 69.6% and 57.4% of the variance on the AzBio at 0 dB SNR and the BKB-SIN, respectively. Conclusions: Although blast-exposed participants reported far more auditory difficulties compared to controls, use of complex stimuli and challenging signal contrasts in cortical and cognitive AEP measures failed to reveal larger group differences than responses to simple stimuli and easy signal contrasts. Despite this, only P3 responses to signals presented in background babble were predictive of subjective auditory complaints. In contrast, cortical N1 and P2 responses were predictive of behavioral SIN performance but not subjective auditory complaints, and use of challenging background babble generally did not improve performance predictions. These results suggest that challenging stimulus protocols are more likely to tap into perceived auditory deficits, but may not be beneficial for predicting performance on clinical measures of SIN understanding. Finally, these results should be interpreted with caution since blast-exposed participants did not perform significantly poorer on tests of SIN perception.

Many military service members and veterans who have been exposed to high-intensity blast waves experience traumatic brain injury (TBI), resulting in chronic auditory deficits despite normal hearing sensitivity. The current study sought to examine the neurological cause of this chronic dysfunction by testing the hypothesis that blast exposure leads to impaired filtering of sensory information at brainstem and early cortical levels. Groups of blast-exposed and non-blast-exposed participants completed self-report measures of auditory and neurobehavioral status, auditory perceptual tasks involving degraded and competing speech stimuli, and physiological measures of sensory gating, including pre-pulse inhibition and habituation of the acoustic startle reflex and electrophysiological assessment of a paired-click sensory gating paradigm. Blast-exposed participants showed significantly reduced habituation to acoustic startle stimuli and impaired filtering of redundant sensory information at the level the auditory cortex. Multiple linear regression analyses revealed that poorer sensory gating at the cortical level was primarily influenced by a diagnosis of TBI, whereas reduced habituation was primarily influenced by a diagnosis of post-traumatic stress disorder. A statistical model was created including cortical sensory gating and habituation to acoustic startle, which strongly predicted performance on a degraded speech task. These results support the hypothesis that blast exposure impairs central auditory processing via impairment of neural mechanisms underlying habituation and sensory gating.

Binaural sensitivity is an important contributor to the ability to understand speech in adverse acoustical environments such as restaurants and other social gatherings. The ability to accurately report on binaural percepts is not commonly measured, however, as extensive training is required before reliable measures can be obtained. Here, we investigated the use of auditory evoked potentials (AEPs) as a rapid physiological indicator of detection of interaural phase differences (IPDs) by assessing cortical responses to 180˚ IPDs embedded in amplitude-modulated carrier tones. We predicted that decrements in encoding of IPDs would be evident in middle age, with further declines found with advancing age and hearing loss. Thus, participants in experiment #1 were young to middle-aged adults with relatively good hearing thresholds while participants in experiment #2 were older individuals with typical age-related hearing loss. Results revealed that while many of the participants in experiment #1 could encode IPDs in stimuli up to 1000 Hz, few of the participants in experiment #2 had discernable responses to stimuli above 750 Hz. These results are consistent with previous studies that have found that aging and hearing loss impose frequency limits on the ability to encode interaural phase information present in the fine structure of auditory stimuli. We further hypothesized that AEP measures of binaural sensitivity would be predictive of participants’ ability to benefit from spatial separation between sound sources, a phenomenon known as spatial release from masking (SRM) which depends upon binaural cues. Results indicate that not only were objective IPD measures well correlated with and predictive of behavioral SRM measures in both experiments, but that they provided much stronger predictive value than age or hearing loss. Overall, the present work shows that objective measures of the encoding of interaural phase information can be readily obtained using commonly available AEP equipment, allowing accurate determination of the degree to which binaural sensitivity has been reduced in individual listeners due to aging and/or hearing loss. In fact, objective AEP measures of interaural phase encoding are actually better predictors of SRM in speech-in-speech conditions than are age, hearing loss, or the combination of age and hearing loss.