Auditory Dysfunction Research Articles

Galectin-3 protects auditory function in female mice

Sex differences in the development of sensorineural hearing loss have been recognized in various inner ear disorders, but the molecular basis for such differences is poorly understood. Autosomal genes have been shown to cause sex differences in disease susceptibility, but many genes exerting sex-dependent effects on auditory function remain to be identified. Galectin-3 (Gal-3), a protein encoded by the autosomal gene Lgals3, is a member of the β-galactoside-binding protein family, and has been linked to multiple biological processes, including immune responses, apoptosis, and cell adhesion. Here, we investigated auditory function and hair cell integrity in Gal-3 knockout (KO, Lgals3−/−) and wild-type (WT, Lgals3+/+) mice from age 1 to 6 months. KO mice show a more rapid age-related increase in ABR thresholds compared to WT mice. Noticeably, the threshold deterioration in female KO mice is significantly greater than in the male KO and WT mice. The ABR threshold elevation manifests over a broad frequency range in female KO mice, whereas the threshold elevations are confined to high frequencies in the male KO and WT mice. Moreover, DPOAE input/output functions reveal a similar pattern of auditory dysfunction, with the female KO mice displaying a significantly greater reduction in DPOAE amplitudes than male KO mice and WT mice of both sexes. Finally, age-related outer hair cell loss is greater for female KO mice compared to male KO mice and WT mice of both sexes. Together, these results indicate that Gal-3 deficiency exacerbates age-related cochlear degeneration and auditory dysfunction in female mice. Our study identifies Gal-3 as a sex-dependent molecule for maintaining female cochlear integrity.

Individual-specific characterization of event-related hemodynamic responses during an auditory task: An exploratory study

Functional near-infrared spectroscopy (fNIRS) has been established as an informative modality for understanding the hemodynamic-metabolic correlates of cortical auditory processing. To date, such knowledge has shown broad clinical applications in the diagnosis, treatment, and intervention procedures in disorders affecting auditory processing; however, exploration of the hemodynamic response to auditory tasks is yet incomplete. This holds particularly true in the context of auditory event-related fNIRS experiments, where preliminary work has shown the presence of valid responses while leaving the need for more comprehensive explorations of the hemodynamic correlates of event-related auditory processing. In this study, we apply an individual-specific approach to characterize fNIRS-based hemodynamic changes during an auditory task in healthy adults. Oxygenated hemoglobin (HbO2) concentration change time courses were acquired from eight participants. Independent component analysis (ICA) was then applied to isolate individual-specific class discriminative spatial filters, which were then applied to HbO2 time courses to extract auditory-related hemodynamic features. While six of eight participants produced significant class discriminative features before ICA-based spatial filtering, the proposed method identified significant auditory hemodynamic features in all participants. Furthermore, ICA-based filtering improved correlation between trial labels and extracted features in every participant. For the first time, this study demonstrates hemodynamic features important in experiments exploring auditory processing as well as the utility of individual-specific ICA-based spatial filtering in fNIRS-based feature extraction techniques in auditory experiments. These outcomes provide insights for future studies exploring auditory hemodynamic characteristics and may eventually provide a baseline framework for better understanding auditory response dysfunctions in clinical populations.

Effects of unilateral eye closure on middle ear muscle contractions

Middle ear muscle contractions (MEMCs) are most commonly considered a response to high-level acoustic stimuli. However, MEMCs have also been observed in the absence of sound, either as a response to somatosensory stimulation or in concert with other motor activity. The relationship between MEMCs and non-acoustic sources is unclear. This study examined associations between measures of voluntary unilateral eye closure and impedance-based measures indicative of middle ear muscle activity while controlling for demographic and clinical factors in a large group of participants (N=190) with present clinical acoustic reflexes and no evidence of auditory dysfunction. Participants were instructed to voluntarily close the eye ipsilateral to the ear canal containing a detection probe at three levels of effort. Orbicularis oculi muscle activity was measured using surface electromyography. Middle ear muscle activity was inferred from changes in total energy reflected in the ear canal using a filtered (0.2 to 8 kHz) click train. Results revealed that middle ear muscle activity was positively associated with eye muscle activity. MEMC occurrence rates for eye closure observed in this study were generally higher than previously published rates for high-level brief acoustic stimuli in the same participant pool suggesting that motor activity may be a more reliable elicitor of MEMCs than acoustic stimuli. These results suggest motor activity can serve as a confounding factor for auditory exposure studies as well as complicate the interpretation of any impulsive noise damage risk criteria that assume MEMCs serve as a consistent, uniform protective factor. The mechanism linking eye and middle ear muscle activity is not understood and is an avenue for future research.

Characterization of hearing-impairment in Generalized Arterial Calcification of Infancy (GACI)

Background and importanceHearing loss (HL) has been sporadically described, but not well characterized, in Generalized Arterial Calcification of Infancy (GACI), a rare disease in which pathological calcification typically presents in infancy.ObjectivesThis study aims to describe the clinical audiologic and otologic features and potential etiology of hearing impairment in GACI and gain pathophysiological insight from a murine model of GACI.DesignCross-sectional cohort study of individuals with GACI. Murine ossicle micromorphology of the ENPP1asj/asj mutant compared to wild-type.SettingClinical research hospital; basic science laboratory.ParticipantsNineteen individuals with GACI who met clinical, biochemical, and genetic criteria for diagnosis.Main outcomes and measuresClinical, biochemical, and radiologic features associated with hearing status.ResultsPure-tone thresholds could be established in 15 (n = 30 ears) of the 19 patients who underwent audiological assessments. The prevalence of HL was 50% (15/30) of ears, with conductive HL in 80% and sensorineural HL in 20%. In terms of patients with HL (n = 8), seven patients had bilateral HL and one patient had unilateral HL. Degree of HL was mild to moderate for 87% of the 15 ears with hearing loss. Of those patients with sufficient pure-tone and middle ear function data, 80% (8/10) had audiometric configurations suggestive of ossicular chain dysfunction (OCD). Recurrent episodes of otitis media (ROM) requiring pressure-equalizing tube placement were common. In patients who underwent cranial CT, 54.5% (6/11) had auricular calcification. Quantitative backscattered electron imaging (qBEI) of murine ossicles supports an OCD component of auditory dysfunction in GACI, suggesting loss of ossicular osteocytes without initiation of bone remodeling.Conclusions and relevanceHearing loss is common in GACI; it is most often conductive, and mild to moderate in severity. The etiology of HL is likely multifactorial, involving dysfunction of the ossicular chain and/or recurrent otitis media. Clinically, this study highlights the importance of early audiologic and otologic evaluation in persons with GACI. Novel findings of high rates of OCD and ROM may inform management, and in cases of unclear HL etiology, dedicated temporal bone imaging should be considered.

Auditory neuropathy: from etiology to management.

Auditory neuropathy is a disorder of auditory dysfunction characterized by the normal function of the outer hair cells and malfunction of the inner hair cells, synapses, postsynapses and/or auditory afferent nervous system. This review summarizes the process of discovery and naming of auditory neuropathy and describes the acquired, associated genetic disorders and management available. In the last 40 years, auditory neuropathy has undergone a process of discovery, naming and progressive elucidation of its complex pathological mechanisms. Recent studies have revealed numerous acquired and inherited causative factors associated with auditory neuropathy. Studies have analyzed the pathogenic mechanisms of various genes and the outcomes of cochlear implantation. New therapeutic approaches, such as stem cell therapy and gene therapy are the future trends in the treatment of auditory neuropathy. A comprehensive understanding of the pathogenic mechanisms is crucial in illustrating auditory neuropathy and assist in developing future management strategies.

Hearing Loss in Offspring Exposed to Antiretrovirals During Pregnancy and Breastfeeding.

Over 27 million people worldwide currently receive daily antiretroviral therapy for the management of HIV/AIDS. In order to prevent the continued spread of HIV, the World Health Organization (WHO) recommends the use of highly active antiretroviral therapy by pregnant and nursing women. There is currently little research into the auditory effects of this therapy on children exposed during pregnancy and breastfeeding, and research to date on the direct effects of antiretroviral exposure on the auditory system is inconclusive. The current study examined the effects of WHO-recommended first-line antiretrovirals in a well-controlled animal model to evaluate the potential for auditory damage and dysfunction following these exposures. Female breeding mice were each exposed to one of four antiretroviral cocktails or a vehicle control once daily during pregnancy and breastfeeding. Offspring of these mice had their auditory status evaluated after weaning using auditory brainstem responses and distortion-product otoacoustic emissions (DPOAEs). Auditory brainstem response thresholds following antiretroviral exposure during gestation and breastfeeding showed elevated thresholds and increased wave latencies in offspring of exposed mice when compared to unexposed controls, but no corresponding decrease in DPOAE amplitude. These differences in threshold were small and so may explain the lack of identified hearing loss in antiretroviral-exposed children during hearing screenings at birth. Minimal degrees of hearing impairment in children have been correlated with decreased academic performance and impaired auditory processing, and so these findings, if also seen in human children, suggest significant implications for children exposed to antiretrovirals during development despite passing hearing screenings at birth.

‘I had nothing. It’s just life experience that helped me through that situation’: Australian audiologists’ perspectives on audiological clinical practice for traumatic brain injury and rehabilitation

ABSTRACT Objective Australian Audiologists’ perspectives on standard non-specialized clinical practice in the context of Traumatic Brain Injury (TBI) were examined, including the perceived barriers to optimal service provision. Design A qualitative research design utilizing semi-structured interviews was conducted using purposive sampling. Nine participants were interviewed about their understanding of the impact of TBI on hearing and balance; identification, diagnosis and management of auditory and vestibular dysfunction following TBI; barriers to service delivery; training relating to complex clients (i.e., TBI); and awareness of referral pathways. Results Three major themes, each with subthemes, were evident in the data. The major themes reflected general considerations of audiological professional culture and specific issues related to knowledge of TBI and clinical practice with patients. Analysis revealed that professional culture seemed to act as a contextual barrier and interacted with the perceived lack of TBI related knowledge to hinder optimal clinical practice in this patient population. Conclusion Application of the biopsychosocial model, including interdisciplinary care in the management of patients with TBI, is needed. An improvement in theoretical and practical knowledge encompassing the wide-ranging effects of TBI is critical for the optimal audiological service delivery.

The Genomics of Auditory Function and Disease.

Current estimates suggest that nearly half a billion people worldwide are affected by hearing loss. Because of the major psychological, social, economic, and health ramifications, considerable efforts have been invested in identifying the genes and molecular pathways involved in hearing loss, whether genetic or environmental, to promote prevention, improve rehabilitation, and develop therapeutics. Genomic sequencing technologies have led to the discovery of genes associated with hearing loss. Studies of the transcriptome and epigenome of the inner ear have characterized key regulators and pathways involved in the development of the inner ear and have paved the way for their use in regenerative medicine. In parallel, the immense preclinical success of using viral vectors for gene delivery in animal models of hearing loss has motivated the industry to work on translating such approaches into the clinic. Here, we review the recent advances in the genomics of auditory function and dysfunction, from patient diagnostics to epigenetics and gene therapy.

Impaired auditory neural performance, another dimension of hearing loss in type-2 diabetes mellitus

AimTo evaluate auditory performance in subjects with poorly controlled type-2 diabetes mellitus, using a simple test battery assessing sensitivity to pure tones and neuronal function. MethodsEnrolled subjects, aged between 23 and 79 years, reported several auditory dysfunctions. They were tested using pure-tone audiometry, otoacoustic emissions for cochlear-function evaluation, and measurement of middle-ear muscle-reflex thresholds in search of an auditory neuropathy. ResultsCompared to the standard established for an age-matched normative population, the distribution of averaged pure-tone thresholds in enrolled subjects shifted by about one standard deviation with respect to the normal distribution, in line with past reports of mild sensorineural hearing impairment in diabetes, even though many diabetic subjects fell well within the normative interval of audiometric thresholds. Otoacoustic emissions showed that pure-tone thresholds correctly predicted the status of cochlear sensory cells that, by amplifying sound, ensure normal hearing sensitivity. Whereas the observed hearing losses should not have affected the acoustic levels above which the protective middle-ear muscle reflex is triggered by intense sounds, this reflex was undetectable in around 40% enrolled subjects, a marker of auditory neuropathy. ConclusionAuditory-neural function should be evaluated to identify diabetic subjects whose hearing is impaired. Simple automatic tests are available for this purpose, for example middle-ear muscle reflex detection, which turns out to be more sensitive than the standard audiogram.

120 Impaired phonemic discrimination in logopenic variant primary progressive aphasia

BackgroundWhilst current diagnostic criteria for primary progressive aphasia syndromes (PPA) emphasise impaired language output and linguistic processing, deficits of auditory analysis are increasingly rec- ognised in PPA syndromes. We assessed phonemic discrimination and its neuroanatomical correlates in patients representing all major PPA variants, compared with typical Alzheimer’s disease (tAD) and healthy age-matched individuals.Methods81 patients with PPA or typical Alzheimer’s disease, and 73 controls performed a phonemic minimal pair discrimination task. Neuroanatomical associations of phonemic discrimination performance across the PPA cohort were assessed using voxel-based morphometry.ResultsPatients with logopoenic variant primary progressive aphasia (lvPPA) as a group performed sig- nificantly worse than both the healthy control group and other PPA variants, after adjusting for auditory verbal working memory. Patients with typical Alzheimer’s disease showed a similar pattern of performance to the lvPPA group. Voxel-based morphometry revealed a significant association of regional grey matter in left angular gyrus with phonemic discrimination performance.ConclusionsImpaired phonemic discrimination is a component of lvPPA and may help differentiate this syndrome from other forms of PPA. These findings speak to the emerging theme of auditory perceptual dysfunction in the progressive aphasias, with implications both for refining diagnostic criteria and developing new clinical biomarkers.jeremy.johnson@doctors.org.uk

121 The Queen Square tests of auditory cognition: defining hearing deficits and dis- ability in dementia

BackgroundHearing impairment has emerged as a potent association of cognitive decline in dementia and a promising treatment target. To realise this promise, we need to resolve fundamental questions concerning the roles of peripheral versus central auditory deficits in different dementias.MethodsUsing a novel psychoacoustic battery – the Queen Square Tests of Auditory Cognition (QSTAC)– we combined pre-existing and novel measures of peripheral and central hearing functions, to charac- terise discrete ‘auditory phenotypes’ across dementia syndromes. Customised auditory symptom ques- tionnaires (completed by patients’ caregivers) were used to capture daily-life hearing-related disability and care burden. Patient groups: Alzheimer’s disease, frontotemporal dementia, primary progressive aphasia (PPA) and control. Neuroanatomical associations of specific hearing deficits were assessed using voxel-based morphometry.ResultsSyndromic signatures of peripheral and central auditory dysfunction were identified. Alzheimer’s disease was associated with prominent impairments of auditory scene analysis and dichotic listening. PPA syndromes and behavioural variant FTD (BvFTD) were principally associated with deficits of sound pattern analysis, sound identity, emotion recognition and degraded speech perception, which stratified according to sub-syndrome (logopoenic, semantic, nonfluent).ConclusionsTaken together, our findings suggest that major dementias have characteristic and differenti- ated auditory phenotypes, reflecting a complex interplay of peripheral hearing and auditory cognitive dysfunction.jeremy.johnson@doctors.org.uk

Nitrative Stress and Auditory Dysfunction.

Nitrative stress is increasingly recognized as a critical mediator of apoptotic cell death in many pathological conditions. The accumulation of nitric oxide along with superoxide radicals leads to the generation of peroxynitrite that can eventually result in the nitration of susceptible proteins. Nitrotyrosine is widely used as a biomarker of nitrative stress and indicates oxidative damage to proteins. Ototoxic insults, such as exposure to noise and ototoxic drugs, enhance the generation of 3-nitrotyrosine in different cell types in the cochlea. Nitrated proteins can disrupt critical signaling pathways and eventually lead to apoptosis and loss of sensory receptor cells in the cochlea. Accumulating evidence shows that selective targeting of nitrative stress attenuates cellular damage. Anti-nitrative compounds, such as peroxynitrite decomposition catalysts and inducible nitric oxide synthase inhibitors, prevent nitrative stress-mediated auditory damage. However, the role of nitrative stress in acquired hearing loss and its potential significance as a promising interventional target is yet to be fully characterized. This review provides an overview of nitrative stress mechanisms, the induction of nitrative stress in the auditory tissue after ototoxic insults, and the therapeutic value of targeting nitrative stress for mitigating auditory dysfunction.

Otologic disorders and management strategies in Turner syndrome

Objective: To analyze the incidence and risk factors of otologic disorders in patients with Turner syndrome (TS), so as to provide management strategies for ear health. Methods: This study is a prospective study based on questionnaires and a cross-sectional study. The TS patients who visited our hospital from 2010 January to 2021 March were included (A total of 71 patients with TS were included in this study. the age of TS diagnosed was 3- to 11-year-old, age of visiting ENT department was 4- to 27-year-old) and the incidence of otologic diseases in different age groups was investigated by questionnaires. The cross-sectional study included ear morphology and auditory function assessment, and further analysis of the risk factors that related to ear disease. Prism was used for data analysis. Results: The investigation found that the incidence of acute otitis media in patients aged 3-6 and 7-12 years was higher than that of patients over 12 years old, which was 33.8%(24/71), 42.9%(30/70)and 23.5%(8/34), respectively; 21.1% (15/71) of patients were recurrent acute otitis media in patients aged 3-6 years, and about 46.6% (7/15)of them persisted beyond 6-year. The prevalence of otitis media with effusion in the three groups was 32.4%(23/71), 34.3%(24/70)and 38.2%(13/34), respectively; the recurrence rate of tympanocentesis was 100%(7/7), 42.9%(3/7)and 50.0%(1/2), which was significantly higher than that of grommet insertion. For age groups of 3-6 and 7-12 years, the prevalence of acute otitis media and secretory otitis media was lower in the X chromosome structure abnormal patients; while for patients older than 12 years, otitis media with effusion was the highest prevalence in Y-chromosome-containing karyotypes. In addition, the prevalence of acute otitis media and otitis media with effusion in patients with other system diseases were increased significantly. A cross-sectional study found that 7.0% (5/71)of the lower auricular, 4.2% (3/71)of the external auditory canal narrow, and 38.0% (27/71)of the tympanic membrane abnormality. 35.2%(25/71) had abnormal hearing, including 17 cases of conductive deafness, 6 cases of sensorineural hearing loss, and 2 cases of mixed deafness. The rest of the patients had normal hearing, but 6 of them had abnormalities in otoacoustic emission. Eustachian tube function assessment found that the eustachian tube dysfunction accounted for 38%(27/71). Hearing loss and abnormal Eustachian tube function were not significantly related to karyotype(Chi-square 2.83 and 2.84,P value 0.418 and 0.417), but significantly related to other system diseases(Chi-square 13.43 and 7.53,P value<0.001). Conclusions: The incidence of TS-related otitis media and auditory dysfunction is significantly higher than that of the general population. It not only occurs in preschool girls, but also persists or develops after school age. Accompanied by other system diseases are risk factors for ear diseases. Clinicians should raise their awareness of TS-related ear diseases and incorporate ear health monitoring into routine diagnosis and treatment.

Associations between medical conditions and auditory dysfunction in US Veterans

Objective To examine associations between non-otologic medical conditions and auditory dysfunction. Design Cross-sectional analysis of baseline data from the Noise Outcomes in Service members Epidemiology (NOISE) study. Logistic regression was used to estimate the association between medical conditions (0, 1, and 2 or more conditions) and auditory dysfunction (hearing loss pure tone average ≥20 dB HL and tinnitus), adjusting for key confounders including noise exposure. Secondarily, the association between specific medical conditions and auditory dysfunction was examined. All variables were self-reported. Study sample United States military Veterans (n = 580) with mean age 34.1 years (standard deviation = 9.2), who were within approximately 2.5 years of separation from service. Results Compared to Veterans reporting no medical conditions, Veterans reporting two or more had increased odds on low-frequency hearing loss and on tinnitus but not on high or extended-high frequency hearing loss. Furthermore, specific conditions sleep disorder and arthritis were associated with auditory dysfunction. Conclusions Non-otologic medical conditions were associated with low-frequency hearing loss and tinnitus in this sample of young Veterans. This suggests medical conditions may play a role in Veterans’ hearing health. Whether management of medical conditions earlier in life reduces the risk of hearing loss and tinnitus requires further study.

Neuromorphological and Neurofunctional Correlates of ADHD and ADD in the Auditory Cortex of Adults.

Attention deficit (hyperactivity) disorder (AD(H)D) is one of the most common neurodevelopmental disorders in children with up to 60% probability of prevailing into adulthood. AD(H)D has far-fetching negative impacts on various areas of life. Until today, no observer-independent diagnostic biomarker is available for AD(H)D, however recent research found evidence that AD(H)D is reflected in auditory dysfunctions. Furthermore, the official diagnostic classification systems, being mainly the ICD-10 in Europe and the DSM-5 in the United States, are not entirely consistent. The neuro-auditory profiles of 82 adults (27 ADHD, 30 ADD, 25 controls) were measured via structural magnetic resonance imaging (MRI) and magnetoencephalography (MEG) to determine gray matter volumes and activity of auditory subareas [Heschl’s gyrus (HG) and planum temporale (PT)]. All three groups (ADHD, ADD, and controls) revealed distinct neuro-auditory profiles. In the left hemisphere, both ADHD and ADD showed reduced gray matter volumes of the left HG, resulting in diminished left HG/PT ratios. In the right hemisphere, subjects with ADHD were characterized by lower right HG/PT ratios and ADD by a similar right HG/PT ratio compared to controls. Controls and ADD had well-balanced hemispheric response patterns, ADHD a left-right asynchrony. With this study, we present the structural and functional differences in the auditory cortex of adult patients with AD(H)D.

Auditory Dysfunction in Animal Models of Autism Spectrum Disorder.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder mainly characterized by social-communication impairments, repetitive behaviors and altered sensory perception. Auditory hypersensitivity is the most common sensory-perceptual abnormality in ASD, however, its underlying neurobiological mechanisms remain elusive. Consistently with reports in ASD patients, animal models for ASD present sensory-perception alterations, including auditory processing impairments. Here we review the current knowledge regarding auditory dysfunction in rodent models of ASD, exploring both shared and distinct features among them, mechanistic and molecular underpinnings, and potential therapeutic approaches. Overall, auditory dysfunction in ASD models seems to arise from impaired central processing. Depending on the model, impairments may arise at different steps along the auditory pathway, from auditory brainstem up to the auditory cortex. Common defects found across models encompass atypical tonotopicity in different regions of the auditory pathway, temporal and spectral processing impairments and histological differences. Imbalance between excitation and inhibition (E/I imbalance) is one of the most well-supported mechanisms explaining the auditory phenotype in the ASD models studied so far and seems to be linked to alterations in GABAergic signaling. Such E/I imbalance may have a large impact on the development of the auditory pathway, influencing the establishment of connections responsible for normal sound processing.

Loss of \u03b24-spectrin impairs Nav channel clustering at the heminode and temporal fidelity of presynaptic spikes in developing auditory brain

Beta-4 (β4)-spectrin, encoded by the gene Sptbn4, is a cytoskeleton protein found at nodes and the axon initial segments (AIS). Sptbn4 mutations are associated with myopathy, neuropathy, and auditory deficits in humans. Related to auditory dysfunction, however, the expression and roles of β4-spectrin at axon segments along the myelinated axon in the developing auditory brain are not well explored. We found during postnatal development, β4-spectrin is critical for voltage-gated sodium channel (Nav) clustering at the heminode along the nerve terminal, but not for the formation of nodal and AIS structures in the auditory brainstem. Presynaptic terminal recordings in Sptbn4geo mice, β4-spectrin null mice, showed an elevated threshold of action potential and increased failures during action potential train at high-frequency. Sptbn4geo mice exhibited a slower central conduction and showed no startle responses, but had normal cochlear function. Taken together, the lack of β4-spectrin impairs Nav clustering at the heminode along the nerve terminal and the temporal fidelity and reliability of presynaptic spikes, leading to central auditory processing deficits during postnatal development.

Long COVID, audiovestibular symptoms and persistent chemosensory dysfunction: a systematic review of the current evidence.

SUMMARYObjectiveThe persistence of auditory, vestibular, olfactory, and gustatory dysfunction for an extended time after COVID-19 has been documented, which represents an emerging challenge of which ENT specialists must be aware. This systematic review aims to evaluate the prevalence of persistent audiovestibolar and olfactory/gustatory symptoms in patients with “long-COVID”.MethodsThe literature was systematically reviewed according to PRISMA guidelines; PubMed, Scopus and Google Scholar were screened by searching articles on audiovestibular symptoms and olfactory/gustatory dysfunction after SARS-CoV-2 infection. The keywords used were hearing loss, tinnitus, vertigo, smell disorders, parosmia, anosmia, hyposmia, dysgeusia combined with COVID-19 or SARS-CoV-2.Results1100 articles were identified. After removal of duplicates (382), 702 articles were excluded, and 16 were included in the systematic review. All articles included identified an association between SARS-CoV-2 infection and persistent hearing or chemosensory impairment. The studies were published over a period of 2 years, between 2019 and 2021.ConclusionsThe likelihood of patients with persistent audiovestibular symptoms related to COVID-19 was different among the articles; however, olfactory and gustatory disturbances were more consistently reported. Studies with longer follow-up are required to fully evaluate the long-term impact of these conditions.

Extended high-frequency pure-tone thresholds predict speech-in-speech recognition even when extended high-frequency speech cues are absent

Recent work has demonstrated that extended high-frequency (EHF; &amp;gt;8 kHz) hearing is valuable for speech-in-noise recognition. These findings contradict the broadly accepted “speech bandwidth” that has historically been limited to below 8 kHz. Several studies also indicate that EHF pure-tone thresholds predict speech-in-noise performance. One question that has arisen is whether the association that has been observed between EHF pure-tone thresholds and speech-in-noise recognition is causal—that loss of audibility of EHF cues in speech degrades speech-in-noise recognition. Indeed, this effect has been demonstrated using low-pass filtering, but whether elevated EHF thresholds would produce a similar effect is not certain. Another possibility is that EHF thresholds are a marker for subclinical dysfunction at lower frequencies that degrades speech recognition. These two possibilities are not mutually exclusive (nor exhaustive) and each could contribute to the observed relationship. Here we present a reanalysis of previous data collected in our lab, the results of which suggest that 16-kHz pure-tone thresholds are consistent predictors of speech-in-speech recognition, regardless of whether EHF cues are present in the speech signal. These findings suggest elevated EHF thresholds may indicate subclinical auditory dysfunction impairing speech-in-speech recognition.

Is jet fuel exposure associated with central auditory nervous system difficulties: An exploratory study in military personnel.

Central auditory nervous system dysfunction (CANSD) can manifest as hearing difficulty in the absence of audiometric abnormalities. Effects of noise or jet fuel exposure on the CANS are documented in animal models and humans. This study screened military personnel using the modified Amsterdam Inventory for Auditory Disability (mAIAD) to assess whether concurrent jet fuel and noise (JFN) exposures potentiate central auditory difficulties compared to noise only exposures. A total of 48 age- and sex-matched participants were recruited: 24 military bulk fuel specialists (JFN) and 24 military personnel without jet fuel exposure. All participants completed the mAIAD, the Noise Exposure Questionnaire, and basic audiological testing. Results revealed non-significant differences in pure-tone thresholds between groups, but the JFN group had higher noise exposures. Additionally, the JFN group revealed consistently lower mAIAD scores compared to the noise only group. Interestingly, a JFN stratified subgroup reporting more listening difficulty exhibited statistically significant lower mAIAD scores in the speech intelligibility in noise subdomain. These preliminary data suggest that jet fuel exposure may potentiate noise-induced CANSD, such as speech-in-noise difficulties. Such difficulties may be more prominent among specific military personnel with combined exposures. Hearing conservation programs could add CANSD screening by use of the mAIAD.