Search

Hearing loss is a common disease affecting public health all around the world. In clinic, auditory brainstem response (ABR) has been widely used for the detection of hearing loss based on its convenience and accuracy. The different reference methods directly influence the quality of the ABR waveform which in turn affects the ABR-based diagnosis. Therefore, in this study, a reference electrode standardization technique (REST) was adopted to systematically investigate and evaluate the effect of different reference methods on the quality of ABR waveform in comparison with the conventional average reference (AR) and mean mastoid (MM) methods. In this study, ABR signals induced by click stimulus were acquired via an EEG electrode cap arrays, and those located on the six channels along the midline were compared systemically. The results showed that, when considering the different channels, the ABR in the Cz channel showed the best morphology. Then, the ABR waveforms acquired via the REST method possessed better morphologies with large amplitude ( 0.06 ± 0.02 μV for wave I, 0.07 ± 0.02 μV for wave III, and 0.21 ± 0.04 μV for wave V) when compared with the traditional method. Summarily, we found that the REST and MM methods improved the quality of ABR on both amplitude and morphology under different stimulation rates and levels without changing the latencies of ABR when compared with the conventional AR method, suggesting that the REST and MM methods have the potential to help physicians with high accurate ABR-based clinical diagnosis. Moreover, this study might also provide a theoretic basis of reference methods on the acquisition of electroencephalogram over public health issues.

Distortion product otoacoustic emissions (DPOAEs) offer an outcome measure to consider for clinical detection and monitoring outer hair cell dysfunction as a result of noise exposure. This investigation detailed DPOAE characteristics and behavioral hearing thresholds up to 20 kHz to identify promising metrics for early detection of cochlear dysfunction. In a sample of normal-hearing individuals with and without self-reported noise exposure, the DPOAE and hearing threshold measures, as assessed by two questions, were examined. The effects on various auditory measures in individuals aged 10–65 years old with clinically normal/near-normal hearing through 4 kHz were evaluated. Individuals reporting occupational noise exposures ( n = 84) and recreational noise exposures ( n = 46) were compared to age-matched nonexposed individuals. The hearing thresholds and DPOAE level, fine structure, and component characteristics for the full frequency bandwidth were examined. The data suggest that the DPOAE levels measured using a range of stimulus levels hold clinical utility while fine structure characteristics offer limited use. Under carefully calibrated conditions, the extension to frequencies beyond 8 kHz in combination with various stimulus levels holds clinical utility. Moreover, this work supports the potential utility of the distortion product place component level for revealing differences in cochlear function due to self-reported, casual noise exposure that are not observable in behavioral hearing thresholds.

Accumulating evidence suggests that cochlear deafferentation may contribute to suprathreshold deficits observed with or without elevated hearing thresholds, and can lead to accelerated age-related hearing loss. Currently there are no clinical diagnostic tools to detect human cochlear deafferentation in vivo. Preclinical studies using a combination of electrophysiological and post-mortem histological methods clearly demonstrate cochlear deafferentation including myelination loss, mitochondrial damages in spiral ganglion neurons (SGNs), and synaptic loss between inner hair cells and SGNs. Since clinical diagnosis of human cochlear deafferentation cannot include post-mortem histological quantification, various attempts based on functional measurements have been made to detect cochlear deafferentation. So far, those efforts have led to inconclusive results. Two major obstacles to the development of in vivo clinical diagnostics include a lack of standardized methods to validate new approaches and characterize the normative range of repeated measurements. In this overview, we examine strategies from previous studies to detect cochlear deafferentation from electrocochleography and auditory brainstem responses. We then summarize possible approaches to improve these non-invasive functional methods for detecting cochlear deafferentation with a focus on cochlear synaptopathy. We identify conceptual approaches that should be tested to associate unique electrophysiological features with cochlear deafferentation.

We tested whether sensitivity to acoustic spectrotemporal modulations can be observed from reaction times for normal-hearing and impaired-hearing conditions. In a manual reaction-time task, normal-hearing listeners had to detect the onset of a ripple (with density between 0-8 cycles/octave and a fixed modulation depth of 50%), that moved up or down the log-frequency axis at constant velocity (between 0-64 Hz), in an otherwise-unmodulated broadband white-noise. Spectral and temporal modulations elicited band-pass filtered sensitivity characteristics, with fastest detection rates around 1 cycle/oct and 32 Hz for normal-hearing conditions. These results closely resemble data from other studies that typically used the modulation-depth threshold as a sensitivity criterion. To simulate hearing-impairment, stimuli were processed with a 6-channel cochlear-implant vocoder, and a hearing-aid simulation that introduced separate spectral smearing and low-pass filtering. Reaction times were always much slower compared to normal hearing, especially for the highest spectral densities. Binaural performance was predicted well by the benchmark race model of binaural independence, which models statistical facilitation of independent monaural channels. For the impaired-hearing simulations this implied a “best-of-both-worlds” principle in which the listeners relied on the hearing-aid ear to detect spectral modulations, and on the cochlear-implant ear for temporal-modulation detection. Although singular-value decomposition indicated that the joint spectrotemporal sensitivity matrix could be largely reconstructed from independent temporal and spectral sensitivity functions, in line with time-spectrum separability, a substantial inseparable spectral-temporal interaction was present in all hearing conditions. These results suggest that the reaction-time task yields a valid and effective objective measure of acoustic spectrotemporal-modulation sensitivity.

OBJECTIVES The purpose of this retrospective cohort study was to compare the relative risks (RR) of hearing impairment due to co-exposure of continuous noise, impulse noise, metal ototoxicants, and organic solvent ototoxicants using several pure tone audiometry (PTA) evaluation methods. DESIGN Noise and ototoxicant exposure and PTA records were extracted from a DoD longitudinal repository and were analyzed for U.S. Air Force personnel (n = 2372) at a depot-level aircraft maintenance activity at Tinker Air Force Base, Oklahoma using an historical cohort study design. Eight similar exposure groups based on combinations of ototoxicant and noise exposure were created: (1) Continuous noise (reference group); (2) Continuous noise + Impulse noise; (3) Metal exposure + Continuous noise; (4) Metal exposure + Continuous noise + Impulse noise; (5) Solvent exposure + Continuous noise; (6) Solvent exposure + Continuous noise + Impulse noise; (7) Metal exposure + Solvent exposure + Continuous noise; and (8) Metal exposure + Solvent exposure + Continuous noise + Impulse noise. RR of hearing impairment compared to the Continuous noise-exposed reference group was assessed with five PTA evaluation methods including (1) U.S. Department of Defense (DoD) Significant Threshold Shift (STS), (2) Occupational Safety and Health Administration (OSHA) age-adjusted STS, (3) National Institute for Occupational Safety and Health (NIOSH) STS, (4) NIOSH Material Hearing Impairment, and (5) All Frequency Threshold Average. RESULTS Hearing impairment was significantly worse for SEG (2) combined exposure to continuous noise and impulse noise only for the PTA evaluation method (2) OSHA Age Adjusted with an RR of 3.11, [95% confidence interval (CI), 1.16-8.31] and was nearly significantly different using PTA evaluation method (4) NIOSH Material Hearing Impairment with an RR of 3.16 (95% CI, 0.99-10.15). Despite no significant differences for SEGs with an ototoxicant exposure, PTA evaluation method (3) NIOSH STS was most sensitive in detecting hearing changes for SEG (8) Metal exposure + Solvent exposure + Continuous noise + Impulse noise as demonstrated by a RR of 1.12 (95% CI, 0.99-1.27). CONCLUSIONS Results suggest that a single PTA evaluation technique may not be adequate in fully revealing hearing impairment risk due to all stressors and tailoring the PTA evaluation technique to the hazards present in the workplace could better detect hearing impairment. Additionally, results suggest that PTA may not be effective as the sole technique for evaluating hearing impairment due to ototoxicant exposure with continuous noise co-exposure.

Loss of inner hair cell-auditory nerve fiber synapses is considered to be an important early stage of neural presbyacusis. Mass potentials, recorded at the cochlear round window, can be used to derive the neural index (NI), a sensitive measure for pharmacologically-induced synapse loss. Here, we investigate the applicability of the NI for measuring age-related auditory synapse loss in young-adult, middle-aged, and old Mongolian gerbils. Synapse loss, which was progressively evident in the 2 aged groups, correlated weakly with NI when measured at a fixed sound level of 60 dB SPL. However, the NI was confounded by decreases in single-unit firing rates at 60 dB SPL. NI at 30 dB above threshold, when firing rates were similar between age groups, did not correlate with synapse loss. Our results show that synapse loss is poorly reflected in the NI of aged gerbils, particularly if further peripheral pathologies are present. The NI may therefore not be a reliable clinical tool to assess synapse loss in aged humans with peripheral hearing loss.

Objective Axenfeld-Rieger syndrome (ARS) type 3 is a rare autosomal dominant disease, characterized by anterior segment dysgenesis of the eye, hearing loss, and cardiac defects. ARS type 3 is highly associated with FOXC1 mutations, which induces developmental disorders of neural crest cells. Most studies about ARS patients focused on ophthalmologic findings, but details in their hearing loss have not yet been revealed. In this report, we investigated audiological and otological manifestations in the ARS type 3 patient who had the novel heterozygous FOXC1 mutation leading deletion at the forkhead DNA-binding domain. Methods and Results Pure tone audiometry showed bilateral sensorineural hearing loss (SNHL) and audiological examinations confirmed that major dysfunctions existed in the cochlea, rather than the spiral ganglion neurons and the cochlear nerve. CT and MRI revealed the hypoplastic cochlea at both sides. Given that the 6p25 deletion syndrome, lacking one allele of the FOXC1 gene, shows similar, but more severe cochlear malformations than the present case, the FOXC1 mutations might contribute to the hypoplasia and dysfunctions in the cochlea. Conclusion To our knowledge, this is the first report demonstrating that the ARS type 3 patient with the FOXC1 mutation has the hypoplasia and dysfunctions in the cochlea, which results in bilateral SNHL.

Introduction Noise-induced hearing loss is one of the most common forms of sensorineural hearing loss. Nevertheless, the mechanisms of noise-induced hearing loss are still not fully understood. Objective To investigate the dynamics of inflammatory responses in the mammalian cochlea following noise trauma at two different times, once during the light cycle and once during the dark. Methods We challenged C57BL/6J mice with moderate, continuous noise trauma at either 9 a.m. or 9 p.m. Auditory function, histological changes in hair cells, and modifications in gene expression levels of inflammatory mediators were assessed at specific time points. Shifts in auditory brainstem response thresholds were measured at 1, 3, 7 and 14 days after noise exposure to measure potential noise-induced hearing loss. Cochlear basilar-membrane immunofluorescent staining was performed at 3 and 14 days after noise exposure. The mRNA levels of several inflammatory mediators were measured via quantitative real-time polymerase chain reaction before (pre) and after (0, 3, 12, 24 and 72 h) noise exposure. Results We found that all noise-exposed mice developed a temporary threshold shift and that there were no significant differences between daytime and nighttime noise exposures in terms of inducing hearing-threshold shifts. Similarly, we did not detect significant histological changes in hair cells between these two groups. However, we discovered an interesting phenomenon in that the peak mRNA levels of IL-1β, IL-6, CCL2 and TNF-α were higher in day noise-exposed mice compared to those in night noise-exposed mice, and these mRNA levels subsided more slowly in day noise-exposed mice. Conclusion Overall, these observations suggest that the circadian timing of noise exposure has a significant effect on noise-induced inflammatory responses in the mouse cochlea and that a greater inflammatory response might occur after daytime exposure.

OBJECTIVES About 15% of U.S. adults report speech perception difficulties despite showing normal audiograms. Recent research suggests that genetic factors might influence the phenotypic spectrum of speech perception difficulties. The primary objective of the present study was to describe a conceptual framework of a deep phenotyping method, referred to as AudioChipping, for deconstructing and quantifying complex audiometric phenotypes. DESIGN In a sample of 70 females 18 to 35 years of age with normal audiograms (from 250 to 8000 Hz), the study measured behavioral hearing thresholds (250 to 16,000 Hz), distortion product otoacoustic emissions (1000 to 16,000 Hz), click-evoked auditory brainstem responses (ABR), complex ABR (cABR), QuickSIN, dichotic digit test score, loudness discomfort level, and noise exposure background. The speech perception difficulties were evaluated using the Speech, Spatial, and Quality of Hearing Scale-12-item version (SSQ). A multiple linear regression model was used to determine the relationship between SSQ scores and audiometric measures. Participants were categorized into three groups (i.e., high, mid, and low) using the SSQ scores before performing the clustering analysis. Audiometric measures were normalized and standardized before performing unsupervised k-means clustering to generate AudioChip. RESULTS The results showed that SSQ and noise exposure background exhibited a significant negative correlation. ABR wave I amplitude, cABR offset latency, cABR response morphology, and loudness discomfort level were significant predictors for SSQ scores. These predictors explained about 18% of the variance in the SSQ score. The k-means clustering was used to split the participants into three major groups; one of these clusters revealed 53% of participants with low SSQ. CONCLUSIONS Our study highlighted the relationship between SSQ and auditory coding precision in the auditory brainstem in normal-hearing young females. AudioChip was useful in delineating and quantifying internal homogeneity and heterogeneity in audiometric measures among individuals with a range of SSQ scores. AudioChip could help identify the genotype-phenotype relationship, document longitudinal changes in auditory phenotypes, and pair individuals in case-control groups for the genetic association analysis.

Experiments in rodent animal models help to reveal the characteristics and underlying mechanisms of pathologies related to hearing loss such as tinnitus or hyperacusis. However, a reliable understanding is still lacking. Here, four different rat strains (Sprague Dawley, Wistar, Long Evans, and Lister Hooded) underwent comparative analysis of electrophysiological (auditory brainstem responses, ABRs) and behavioral measures after noise trauma induction to differentiate between strain-dependent trauma effects and more consistent changes across strains, such as frequency dependence or systematic temporal changes. Several hearing- and trauma-related characteristics were clearly strain-dependent. Lister Hooded rats had especially high hearing thresholds and were unable to detect a silent gap in continuous background noise but displayed the highest startle amplitudes. After noise exposure, ABR thresholds revealed a strain-dependent pattern of recovery. ABR waveforms varied in detail among rat strains, and the difference was most prominent at later peaks arising approximately 3.7 ms after stimulus onset. However, changes in ABR waveforms after trauma were small compared to consistent strain-dependent differences between individual waveform components. At the behavioral level, startle-based gap-prepulse inhibition (gap-PPI) was used to evaluate the occurrence and characteristics of tinnitus after noise exposure. A loss of gap-PPI was found in 33% of Wistar, 50% of Sprague Dawley, and 75% of Long Evans rats. Across strains, the most consistent characteristic was a frequency-specific pattern of the loss of gap-PPI, with the highest rates at approximately one octave above trauma. An additional range exhibiting loss of gap-PPI directly below trauma frequency was revealed in Sprague Dawley and Long Evans rats. Further research should focus on these frequency ranges when investigating the underlying mechanisms of tinnitus induction.

Objective To study the impact of cardiovascular diseases (CVDs) on hearing deterioration among ageing adults in a longitudinal setting. Furthermore, to describe the pure tone threshold changes at the 0.125-8 kHz frequency range over 13 years. Design A population-based follow-up study. Study sample A random sample of 850 adults, of whom 559 participated in the follow-up study. Otological examination, a structured interview, and pure tone audiometry were conducted. Multivariate regression models were used to estimate the effect of CVD (participants had at least one cardiovascular condition) on hearing deterioration of the better ear hearing level (BEHL), defined as a change in the pure-tone average (PTA) of the frequencies 0.5, 1, 2, and 4 kHz and separately at the lower (0.125, 0.25, and 0.5 kHz) and higher (4, 6, and 8 kHz) frequencies. Results In the multivariable-adjusted analysis, the BEHL change at 13 years was 0.7 dB greater among participants with CVD (p = 0.3). The mean BEHL change during the 13-year follow-up was 12.0 dB (95% CI 11.4-12.6) among all participants. Conclusions No significant association between CVD and hearing threshold changes was found.

Previous studies have reported the relationship between effect of caffeine and many diseases. However, studies to evaluate the association between caffeine and hearing loss are contradictory. To examine the relationship of urinary caffeine metabolites with the hearing threshold in US adults, a total of 849 adults aged 20–69 years who participated in the National Health and Nutrition Examination Survey (NHANES, 2011–2012) were enrolled in this study. Urinary caffeine and its 14 metabolites were applied as biomarkers to assess caffeine exposure. Hearing loss was defined as mean pure tone averages > 25 dB HL at 500, 1000, and 2000 Hz in both ears (low frequency); and 3000, 4000, and 6000 Hz in both ears (high frequency). Univariate and multivariate linear regression analyses were conducted to examine the associations of urinary caffeine metabolites with low- and high-frequency hearing thresholds, respectively. Low-frequency hearing loss were 5.08% and 6.10% in male and female participants, respectively; and high-frequency hearing loss were 31.81% and 15.14% in male and female participants, respectively. In the unadjusted model, the P value for trend shows that urinary caffeine metabolites 137X and AAMU were significantly associated with low-frequency PTA, and that 17X, 137X, AAMU were significantly associated with high-frequency PTA, but when the model was adjusted for sex, age, education level, firearm noise exposure, occupational noise exposure, recreational noise exposure, serum cotinine, body mass index, diabetes, hypertension, these were no longer statistically significant. In conclusion, urinary caffeine metabolites were not associated with the hearing threshold shifts in US adults.

Exposure to intense noise can damage cochlear hair cells, leading to hearing loss in mammals. To avoid this constraint, most mammals have evolved in relatively quiet environments. Echolocating bats, however, are naturally exposed to continuous intense sounds from their own and neighboring sonar emissions for maintaining sonar directionality and range. Here, we propose the presence of intense noise resistance in cochlear hair cells of echolocating bats against noise-induced hearing loss (NIHL). To test this hypothesis, we performed noise exposure experiments for laboratory mice, one nonecholocating bat species, and five echolocating bat species. Contrary to nonecholocating fruit bats and mice, the hearing and the cochlear hair cells of echolocating bats remained unimpaired after continuous intense noise exposure. The comparative analyses of cochleae transcriptomic data showed that several genes protecting cochlear hair cells from intense sounds were overexpressed in echolocating bats. Particularly, the experimental examinations revealed that ISL1 overexpression significantly improved the survival of cochlear hair cells. Our findings support the existence of protective effects in cochlear hair cells of echolocating bats against intense noises, which provides new insight into understanding the relationship between cochlear hair cells and intense noises, and preventing or ameliorating NIHL in mammals.

OBJECTIVES Humans can hear up to 20 kHz. Emerging evidence suggests that hearing in the extended high frequencies (EHFs; >8 kHz) contributes to speech perception in noise. The objective of the present study was to describe the features of EHF hearing impairment in young adults with normal standard audiograms (0.25-8 kHz). Specifically, the study goals were to: (1) characterize the EHF hearing impairment and identify potential risk factors; (2) elucidate the age-related changes in EHF hearing; (3) determine the effect of EHF hearing impairment on speech-in-noise recognition; and (4) examine the extent to which EHF hearing impairment influences cochlear functioning in the standard frequencies. DESIGN Hearing thresholds at standard frequencies and EHFs (10, 12.5, 14, and 16 kHz), and speech recognition thresholds (SRTs) using digit triplets in multi-talker babble were measured in both ears from 222 participants (19-38 years; n = 444 ears) with normal audiograms (≤20 dB HL at standard frequencies). Test-retest measurement of hearing thresholds was obtained in a subset of 50 participants (100 ears), and clinical distortion product otoacoustic emissions (f2 frequency = 2, 3, 4, and 5 kHz) were recorded in 49 participants (98 ears). RESULTS Forty-two of 222 participants had EHF hearing impairment (>20 dB HL for at least one EHF in either ear). Only seven individuals with EHF impairment had significant case history and/or listening-in-noise complaints. A breakpoint in the threshold-age function was observed for the EHFs for males but not for females. Linear mixed models revealed a significant effect of age, pure-tone averages for speech frequencies (0.5, 1, 2, and 4 kHz), and EHFs and group (NH versus EHF hearing impairment) independent of each other on the SRTs. Individuals with EHF hearing impairment had less measurable emissions and when present, had a lower magnitude of otoacoustic emissions relative to NH controls. There was no difference in hearing thresholds, SRTs, or otoacoustic emissions between earphone users and nonusers. CONCLUSIONS The hearing thresholds for the EHFs exhibit signs of early auditory aging. Age-related deterioration in auditory function can be observed in the third decade of human life. A breakpoint in the threshold-age function suggests that rapid aging processes are operational at a relatively younger age (21 years) for males. The audibility of EHFs contributes to speech-in-noise recognition. EHF hearing impairment independent of age and speech frequencies can affect speech-in-noise recognition. Reduced distortion product otoacoustic emissions in the standard frequencies may suggest preclinical cochlear degeneration in individuals with EHF hearing impairment.

Age-related hearing loss (ARHL) is a devastating public health issue. To successfully address ARHL using existing and future treatments, it is imperative to detect the earliest signs of age-related auditory decline and understand the mechanisms driving it. Here, we explore early signs of age-related auditory decline by characterizing cochlear function in 199 ears aged 10–65 years, all of which had clinically defined normal hearing (i.e., behavioral thresholds ≤ 25 dB HL from .25 to 8 kHz bilaterally) and no history of noise exposure. We characterized cochlear function by measuring behavioral thresholds in two paradigms (traditional audiometric thresholds from .25 to 8 kHz and Békésy tracking thresholds from .125 to 20 kHz) and distortion product otoacoustic emission (DPOAE) growth functions at f(2) = 2, 4, and 8 kHz. Behavioral thresholds through a standard clinical frequency range (up to 8 kHz) showed statistically, but not clinically, significant declines across increasing decades of life. In contrast, DPOAE growth measured in the same frequency range showed clear declines as early 30 years of age, particularly across moderate stimulus levels (L(2) = 25–45 dB SPL). These substantial declines in DPOAE growth were not fully explained by differences in behavioral thresholds measured in the same frequency region. Additionally, high-frequency Békésy tracking thresholds above ~11.2 kHz showed frank declines with increasing age. Collectively, these results suggest that early age-related cochlear decline (1) begins as early as the third or fourth decade of life, (2) is greatest in the cochlear base but apparent through the length of the cochlear partition, (3) cannot be detected fully by traditional clinical measures, and (4) is likely due to a complex mix of etiologies.

Little is known about peripheral auditory function in young adults with HIV, who might be expected to show early evidence of hearing loss if HIV infection or treatment does affect peripheral function. The goal of this study was to compare peripheral auditory function in 2 age- and gender-matched groups of young adults with clinically normal hearing with and without HIV.Matched cohort study with repeated measures.Infectious disease center in Dar es Salaam, Tanzania.Participants included HIV-positive (n = 38) and HIV-negative (n = 38) adults aged 20 to 30 years who had clinically normal hearing, defined as type A tympanograms, air conduction thresholds ≤25 dB HL bilaterally from 0.5 to 8 kHz, and distortion product otoacoustic emissions (DPOAEs)6 dB above the noise floor bilaterally from 1.5 to 8 kHz. Participants were tested multiple times over 6-month intervals (average, 2.7 sessions/participant) for a total of 208 observations. Primary outcome measures included tympanograms, air conduction audiograms, DPOAEs, and click-evoked auditory brainstem responses.HIV groups did not significantly differ in age, static immittance, or air conduction thresholds. HIV-positive status was independently associated with approximately 3.7-dB lower DPOAE amplitudes from 2 to 8 kHz (95% CI, 1.01-6.82) in both ears and 0.04-µV lower (95% CI, 0.003-0.076) auditory brainstem response wave I amplitudes in the right ear.Young adults living with HIV have slightly but reliably smaller DPOAEs and auditory brainstem response wave I amplitudes than matched HIV-negative controls. The magnitude of these differences is small, but these results support measuring peripheral auditory function in HIV-positive individuals as they age.

Purpose To report the outcomes and the patients’ subjective experience of cochlear implantation (CI) performed under local anesthesia (LA). To describe a new form of intraoperative cochlear monitoring based on the patients subjective sound perception during CI. Methods In this retrospective case–cohort study, 117 patients underwent CI under LA with (n = 58) or without conscious sedation (n = 59). Included were primarily elderly patients with elevated risks for general anesthesia and recently patients with residual hearing eligible for electro-acoustic stimulation (EAS) (n = 27), in whom hearing could be monitored during the electrode insertion. A 500 Hz test tone was presented and the patient reported of subjective changes in loudness, leading to a modification of the insertion. A questionnaire was sent to all patients in which they assessed their subjective experience. Results All patients were successfully operated under LA without the need to intraoperatively convert to general anesthesia. 90% of the patients reported that the surgery was a positive experience. The vast majority, 90% of patients were satisfied with the overall treatment and with intraoperative pain management and 84% of the patients would opt for local anesthesia again. Cochlear monitoring by the patients’ subjective sound perception enabled for atraumatic insertions as all EAS patients could hear the test tone up to the end of the surgery. Conclusions CI under LA was well tolerated and recommended by the vast majority of patients. In addition, it offers the possibility to monitor the patients’ hearing during the electrode insertion, which may help to prevent insertion trauma.

Introduction Current Brazilian legislation requires that all workers exposed to noise are to be given an audiogram upon hiring, after 6 months of employment (first periodic test), and annually after the first periodic test. In other countries, the regulations of hearing conservation programs do not include the requirement for audiometric testing at 6 months of employment, but only annually. There is no evidence that the periodicity adopted by Brazilian legislation is the most appropriate. Objective The present study aimed to evaluate the first 3 occupational audiometric tests of workers exposed to noise. Methods Historical cohort study with cross-sectional analysis. Participants were all male metallurgy workers aged up to 40 years. The first 3 audiograms of each worker were analyzed: pre-employment audiometric test, periodic audiometric test 1, and periodic audiometric test 2. For each worker, mean frequency thresholds were calculated at 3, 4, and 6 kHz in the left and right ears for each test. Statistical analysis was performed using the nonparametric Wilcoxon test. Results A total of 988 workers were included. There was a significant difference in auditory thresholds between the pre-employment test and the 2 subsequent periodic tests for the right and left ears. There was no significant difference between Test1 and Test2 in either ear. Conclusion Given the lack of difference between the first 2 periodic tests, we believe that they could be merged into a single test, i.e., first periodic audiometric testing could be performed at 12 months of employment without compromising workers’ health.

ObjectiveThis study investigated the characteristics and prognosis of the feeling of ear fullness in patients with unilateral all-frequency sudden sensorineural hearing loss.MethodsOur study included 56 patients with a diagnosis of unilateral all-frequency sudden sensorineural hearing loss accompanied by a feeling of ear fullness and 48 patients without a feeling of ear fullness. The condition of these patients was prospectively observed.ResultsPositive correlations were observed between grading of feeling of ear fullness and hearing loss in patients with a feeling of ear fullness (r = 0.599, p < 0.001). No significant differences were observed in the total effective rate of hearing recovery between patients with and without a feeling of ear fullness after one month of treatment (Z = −0.641, p = 0.521). Eighty-six per cent of patients (48 out of 56) showed complete recovery from the feeling of ear fullness. There was no correlation between feeling of ear fullness recovery and hearing recovery (r = 0.040, p = 0.769).ConclusionThe prognosis of feeling of ear fullness is good. There was no correlation between feeling of ear fullness recovery and hearing recovery for all-frequency sudden sensorineural hearing loss patients.

OBJECTIVES The goal of this study is to determine if chronic obstructive pulmonary disease (COPD) is associated with sensorineural hearing loss (SNHL) in a national database. STUDY DESIGN Cross-sectional study. SETTING National sample of the United States population. PATIENTS Adults with audiometric and spirometry data from the National Health and Nutrition Examination Study (NHANES) database. INTERVENTIONS None. METHODS A total of 2,464 adults with spirometry and audiometry data from the NHANES database (2009-2012) were studied. Outcome measures included hearing, measured by high-frequency pure tone average (HFPTA; 3, 4, 6, 8 kHz) and low-frequency pure tone average (LFPTA; .5, 1, 2 kHz) frequencies. SNHL was defined as a HFPTA or LFPTA threshold more than 25 decibels (dB) in the better ear. Multivariable regression analyses explored the association between hearing loss and COPD. RESULTS The prevalence of COPD was 19.8% in individuals with SNHL in the better ear and 4.7% in individuals with normal hearing (p

Objective Non-echo planar diffusion weighted magnetic resonance imaging is a reliable surveillance tool of residual cholesteatoma nowadays. It is not known whether the material of the ossicular chain prosthesis modifies the sensitivity and specificity of MRI in these cases. The aim of the study was to compare the sensitivity, specificity and a localization-specific accuracy of non-EPI DW MRI sequences for residual cholesteatoma in the following 3 subgroups: patients with titanium ossicular prosthesis (group T), with autologous cortical bone columella (group A) or without any reconstruction (group WR) of hearing bones. Methods This prospective study covered 28 cases with cholesteatoma of the middle ear undergone second-look surgery, who had preoperative PROPELLER DW-MRI. Surgical findings were compared to the results of the DWI-MRI. Results The overall sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were: 0.76-0.8-0.76-0.8. Group T, group A and group WR sensitivity was 0.83-0.6-1, specificity: 0.75-0.75-0.85, PPV: 0.83-0.75-0.66, NPV: 0.75-0.6-1. Overall accuracy was 0.78. Size of missed cholesteatoma was 2-4 mm (mean: 2.66±1.15). Conclusions Various materials are suitable for ossicular chain reconstruction. The poor detectability of residual or recurrent cholesteatoma in the middle ears reconstructed with autologous bony prosthesis may still claim second-look surgery instead of the usage of non- EPI DWI sequences independently in these patients.

Objective This study was aimed to determine the characteristics of middle ear cholesteatoma and to investigate short-term outcomes regarding the rates of residual and recurrent cholesteatoma and the postoperative hearing results in Japan, via a nationwide survey using staging and classification criteria for middle ear cholesteatoma, as proposed by the Japan Otological Society (JOS). Methods The first-round survey was conducted in 2016. The target was patients with middle ear cholesteatoma who were surgically treated in Japan between January and December 2015. Medical information on the patients was anonymized. The questionnaire entries were age, sex, cholesteatoma classification and stage, preoperative hearing level, mastoid development, status of the stapes, and surgical method. There were a total of 1,787 registered patients from 74 facilities from all over Japan. The second survey was conducted in January 2018 and received 1,456 responses from 49 facilities in Japan. Of the 1,456 cases, 1,060 were conducted in the postoperative hearing survey and 1,084 in the residual recurrence survey. Results The most common cholesteatoma type was pars flaccida cholesteatoma (63.3%), followed by pars tensa cholesteatoma (13.0%), congenital cholesteatoma (12.9%), and cholesteatoma secondary to chronic tensa perforation (5.6%). Cholesteatoma of uncertain origin accounted for 5.0% (90 cases). Stage II was predominant in pars flaccida and pars tensa cholesteatoma, which frequently involves the mastoid, whereas about half of cases of cholesteatoma secondary to chronic tensa perforation and congenital cholesteatoma were classified as stage I. One hundred fifty-two of 1,084 cases (14.0%) had recurrent cholesteatoma, residual cholesteatoma, or both following first surgeries. The postoperative rates of hearing success rate was 63.3%. Conclusion We were able to clarify not only the current epidemiological status of middle ear cholesteatoma but also the current trends of cholesteatoma surgery in Japan. The development of a staging system by the JOS Committee serving an epidemiological database for international or time-dependent comparison. It is possible to use this staging system with reasonable reliability.

Purpose In most cases, tinnitus co-exists with hearing loss, suggesting that poorer speech understanding is simply due to a lack of acoustic information reaching the central nervous system (CNS). However, it also happens that patients with tinnitus who have normal hearing also report problems with speech understanding, and it is possible to suppose that tinnitus is to blame for difficulties in perceptual processing of auditory information. The purpose of the study was to evaluate the auditory processing abilities of normally hearing subjects with and without tinnitus. Methods The study group comprised 97 adults, 54 of whom had normal hearing and chronic tinnitus (the study group) and 43 who had normal hearing and no tinnitus (the control group). The audiological assessment comprised pure-tone audiometry and high-frequency pure-tone audiometry, impedance audiometry, and distortion product oto-acoustic emission assessment. To evaluate possible auditory processing deficits, the Frequency Pattern Test (FPT), Duration Pattern Test (DPT), Dichotic Listening Test (DLT), and Gap Detection Threshold (GDT) tests were performed. Results The tinnitus subjects had significantly lower scores than the controls in the gap detection test (p p Conclusion In normally hearing patients, the presence of tinnitus may be accompanied with auditory processing difficulties.

ObjectiveTo compare the measured bone conduction threshold at 3 kHz with the calculated threshold in newly diagnosed sudden sensorineural hearing loss.MethodsA retrospective chart review was conducted of pure tone audiograms in confirmed sudden sensorineural hearing loss cases.ResultsOf 157 patients with sudden sensorineural hearing loss, 144 had idiopathic hearing loss, 8 had vestibular schwannoma and 5 had Ménière's disease. The r value for the correlation between the two methods of 3 kHz assessment for all patients was 0.887 (p < 0.001). The mean difference between the measured and calculated 3 kHz thresholds was 0.76 ± 7.96 dB, 0.4 ± 8.08 dB and 1.5 ± 1.8 dB in the sudden sensorineural hearing loss, idiopathic and Ménière's disease groups, respectively. The mean difference between the measured and calculated 3 kHz thresholds was significantly greater in the vestibular schwannoma group (6.86 ± 4.38 dB) than in the idiopathic group (p = 0.013).ConclusionThe 3 kHz frequency may encompass important audiometric information. A discrepancy between the measured and calculated bone conduction 3 kHz thresholds raises suspicion of an underlying vestibular schwannoma as an aetiology for sudden sensorineural hearing loss, and these thresholds should therefore be measured independently and routinely.

Numerous studies have documented the adverse effects of high-dose radiation on hearing in patients. On the other hand, radiographers are exposed to a low dose of ionizing radiation, and the effect of a low dose of radiation on hearing is quite abstruse. Therefore, the present systematic review aimed to elucidate the effect of low-dose ionizing radiation on hearing. Two authors independently carried out a comprehensive data search in three electronic databases, including PUBMED/MEDLINE, CINAHL, and SCOPUS. Eligible articles were independently assessed for quality by two authors. Cochrane Risk of Bias tool was used assess quality of the included studies. Two articles met the low-dose radiation exposure criteria given by Atomic Energy Regulatory Board (AERB) and National Council on Radiation Protection (NCRP) guidelines. Both studies observed the behavioral symptoms, pure-tone hearing sensitivity at the standard, extended high frequencies, and the middle ear functioning in low-dose radiation-exposed individuals and compared with age and gender-matched controls. One study assessed the cochlear function using transient-evoked otoacoustic emissions (TEOAE). Both studies reported that behavioral symptoms of auditory dysfunction and hearing thresholds at extended high frequencies were higher in radiation-exposed individuals than in the controls. The current systematic review concludes that the low-dose ionizing radiation may affect the hearing adversely. Nevertheless, further studies with robust research design are required to explicate the cause and effect relationship between the occupational low-dose ionizing radiation exposure and hearing.

OBJECTIVE To examine the prevalence of hearing impairment in children with hypothyroidism, and to characterize clinical and subclinical hearing loss by examining cochlear function, auditory brainstem pathways, and integration of the auditory system as a whole. DESIGN An electronic search was conducted using PubMed, Scopus, and Cochrane Library databases. This systematic review was performed in accordance with the PRISMA guidelines. Original observational studies that utilized audiological tests for auditory system evaluations in hypothyroidism were included. A total of 2004 studies were found in the search, with 23 studies meeting the inclusion criteria. RESULTS The pooled prevalence of hearing loss was 16.1% [95% confidence interval 10.7, 22.4] for children with congenital hypothyroidism. Hearing thresholds at pure-tone averages (0.5-2 kHz) were 1.6 dB [95% confidence interval 1.7, 4.8] higher for children with hypothyroidism compared to age-matched controls. Cochlear dysfunction was detected at middle frequencies (1-3 kHz) by otoacoustic emission testing, indicating abnormalities of hair cell function or cochlear integration. Retrocochlear involvement was detected on auditory brainstem response (ABR), with prolonged Wave I indicating a peripheral conduction abnormality localized to the middle or inner ear and eighth cranial nerve. CONCLUSIONS Children with hypothyroidism have a higher prevalence of hearing loss than children without hypothyroidism. For children with congenital hypothyroidism, evidence of subclinical abnormalities at the level of the cochlea and eighth cranial nerve are present despite early initiation of levothyroxine therapy. Dysfunction of the auditory system might begin with predominance of peripheral conduction abnormalities early in development.

Recently, it was proposed that a processing principle called adaptive stochastic resonance plays a major role in the auditory system, and serves to maintain optimal sensitivity even to highly variable sound pressure levels. As a side effect, in case of reduced auditory input, such as permanent hearing loss or frequency specific deprivation, this mechanism may eventually lead to the perception of phantom sounds like tinnitus or the Zwicker tone illusion. Using computational modeling, the biological plausibility of this processing principle was already demonstrated. Here, we provide experimental results that further support the stochastic resonance model of auditory perception. In particular, Mongolian gerbils were exposed to moderate intensity, non-damaging long-term notched noise, which mimics hearing loss for frequencies within the notch. Remarkably, the animals developed significantly increased sensitivity, i.e. improved hearing thresholds, for the frequency centered within the notch, but not for frequencies outside the notch. In addition, most animals treated with the new paradigm showed identical behavioral signs of phantom sound perception (tinnitus) as animals with acoustic trauma induced tinnitus. In contrast, animals treated with broadband noise as a control condition did not show any significant threshold change, nor behavioral signs of phantom sound perception.

Cochlear implants use electrical stimulation of the auditory nerve to restore the sensation of hearing to deaf people. Unfortunately, the stimulation current spreads extensively within the cochlea, resulting in “blurring” of the signal, and hearing that is far from normal. Current spread can be indirectly measured using the implant electrodes for both stimulating and sensing, but this provides incomplete information near the stimulating electrode due to electrode-electrolyte interface effects. Here, we present a 3D-printed “unwrapped” physical cochlea model with integrated sensing wires. We integrate resistors into the walls of the model to simulate current spread through the cochlear bony wall, and “tune” these resistances by calibration with an in-vivo electrical measurement from a cochlear implant patient. We then use this model to compare electrical current spread under different stimulation modes including monopolar, bipolar and tripolar configurations. Importantly, a trade-off is observed between stimulation amplitude and current focusing among different stimulation modes. By combining different stimulation modes and changing intracochlear current sinking configurations in the model, we explore this trade-off between stimulation amplitude and focusing further. These results will inform clinical strategies for use in delivering speech signals to cochlear implant patients.

Purpose The purpose of this study is to use variability on tests of basic auditory processing to allow identification of those tests that could be used clinically to describe functional hearing ability beyond the pure-tone audiogram and clinical speech-in-noise tests. Method Psychoacoustic tests implemented using the Portable Automated Rapid Testing system on a calibrated iPad were evaluated for nine young normal-hearing participants ( M age = 21.3, SD = 2.5) and seven hearing-impaired participants ( M age = 64.9, SD = 13.5). Participants completed 10 psychoacoustic subtests in a quiet room. Correlational analyses were used to compare performance on the psychoacoustic test battery with performance on a clinical speech-in-noise test and with the 4-frequency pure-tone average (4FreqPTA). Results Spectral processing ability was highly correlated with 4FreqPTA, and temporal processing ability showed minimal variability across the hearing-impaired group. Tests involving binaural processing captured variability across hearing-impaired listeners not associated with 4FreqPTA or speech-in-noise performance. Conclusions Tests that capture the ability to use binaural cues may add information to what current clinical protocols reveal about patients with auditory complaints. Further testing with a larger sample size is needed to confirm the need for binaural measurements and to develop normative data for clinical settings.

Purpose To assess the hearing function of patients with mild and moderate COVID-19. Methods The hospital staffs recovered from COVID-19 were included. The candidates who had an ear disease or progressive hearing loss prior to COVID-19, or having been hospitalised because of severe and critical COVID-19 were excluded. The age, sex, symptoms during COVID-19, and medications received for the disease were noted. The hearing thresholds (HT) of the participants who had an audiogram before having COVID-19 disease were recorded. A pure tone audiometry was conducted to all. The participants were classified into two groups; Group 1: participants who had an audiogram previously, Group 2: participants who didn’t have an audiogram previously. The changes of the HTs of the participants in Group 1 were analyzed. The HTs of the participants in Group 2 were documented without any comparison. The HTs of all participants were also analyzed by classifying them into subgroups according to their symptoms during, and medications received for COVID-19. Results Fifty-four males and 47 females (18–59 years) were included. The participants’ HTs in Group 1 (n = 31) did not change significantly at any of the frequencies after having COVID-19 (p > 0.05). The pure tone averages of the participants in Group 2 (n = 70) were below 25 dB and none of the participants reported worsening of their hearing permanently. The differences between the HTs of none of the subgroups were statistically significant (p > 0.05, p > 0.05). Conclusions Mild and moderate COVID-19 and its treatments did not affect the hearing function permanently.

Human hearing loss is often accompanied by comorbidities like tinnitus. This perception of phantom sounds without external stimulation is affecting up to 15% of the adult population and can lead to psychological disorders like depression. Animal studies in rodents could show that tinnitus may not only be a result of hearing loss due to cochlear hair cell damage but can also be a consequence of synaptopathy at the inner hair cells already induced by moderate sound traumata (hidden hearing loss). In this study we investigate the synaptopathy previously shown in mice in our animal model, the Mongolian gerbil, and relate it to behavioral signs of tinnitus in this species. Tinnitus was induced by a mild monaural acoustic trauma leading to a monaural noise induced hearing loss in the animals quantified by auditory brainstem response audiometry. Behavioral signs of tinnitus percepts were detected by measurement of pre-pulse inhibition of the acoustic startle response in a gap-noise paradigm in about two-thirds of the animals. 14 days after trauma the cochleae of traumatized and non-traumatized ears were isolated and inner hair cell synapses were counted within several spectral regions of the cochlea. In the here presented preliminary data inner hair cell synaptopathy was only found in animals with behavioral signs of tinnitus, independent of type of hearing loss. On the other hand, animals with apparent hearing loss but without behavioral signs of tinnitus showed a reduction in amplitudes of auditory brainstem response waves I/II (cochlear nerve and dorsal cochlear nucleus) but no significant changes in the number of synapses at the inner hair cells. We conclude – in line with the literature – that hearing loss is caused by damage to the inner and / or outer hair cells but that the development of tinnitus, at least in our animal model is closely linked to synaptopathy at the inner hair cells.

The auditory biology of Monachinae seals is poorly understood. Limited audiometric data and certain anatomical features suggest that these seals may have reduced sensitivity to airborne sounds compared to related species. Here, we describe the in-air hearing abilities of a Hawaiian monk seal (Neomonachus schauinslandi) trained to participate in a psychophysical paradigm. We report absolute (unmasked) thresholds for narrowband signals measured in quiet conditions across the range of hearing and masked thresholds measured in the presence of octave-band noise at two frequencies. The behavioral audiogram indicates a functional hearing range from 0.1 to 33 kHz and poor sensitivity, with detection thresholds above 40 dB re 20 µPa. Critical ratio measurements are elevated compared to those of other seals. The apparently reduced terrestrial hearing ability of this individual—considered with available auditory data for a northern elephant seal (Mirounga angustirostris)—suggests that hearing in Monachinae seals differs from that of the highly sensitive Phocinae seals. Exploration of phylogenetic relationships and anatomical traits support this claim. This work advances understanding of the evolution of hearing in amphibious marine mammals and provides updated information that can be used for management and conservation of endangered Hawaiian monk seals. Supplementary Information The online version contains supplementary material available at 10.1007/s00359-021-01498-y.

Purposes The aims of this study are (a) to characterize the hearing of adolescents from four schools of Córdoba, Argentina, through the analysis of conventional and extended high-frequency audiometric thresholds and otoacoustic emissions (OAEs) and (b) to analyze the association between the mentioned hearing tests and exposure to music. Method It was a cross-sectional correlational descriptive study. Hearing thresholds (250–16000 Hz), transient evoked OAEs, and distortion product OAEs were evaluated in 225 adolescents (450 ears) aged 14 and 15 years. The ears were split into two groups: Group 1 had thresholds ≤ 21 dB HL in all frequencies, and Group 2 had thresholds > 21 dB HL in at least one. Exposure to music was evaluated through a questionnaire. Results Statistically significant differences were found in both ears between Groups 1 and 2. A notch at 3000–6000 Hz was noted in both groups. Group 2 showed a progressive threshold increase from 9000 Hz. Amplitude decrease, negative values, absent distortion product OAEs, and transient evoked OAEs were noted even in Group 1. A statistically significant association between Groups 1 and 2 and the presence/absence of OAEs was observed in most frequencies. Ears with moderate or high exposure to music had greater hearing thresholds compared to ears with low exposure at most frequencies; this was more evident in Group 1. Regarding exposure to music and OAEs, no significant differences were found between the exposure categories. Conclusions The findings highlight the value of implementing hearing conservation programs in Argentina, analyzing hearing tests correlated with questionnaires about recreational noise exposure in order to detect vulnerable ears early.

It is widely accepted that even a single acute noise exposure at moderate intensity that induces temporary threshold shift (TTS) can result in permanent loss of ribbon synapses between inner hair cells and afferents. However, effects of repeated or chronic noise exposures on the cochlear synapses especially medial olivocochlear (MOC) efferent synapses remain elusive. Based on a weeklong repeated exposure model of bandwidth noise over 2-20 kHz for 2 hours at seven intensities (88 to 106 dB SPL with 3 dB increment per gradient) on C57BL/6J mice, we attempted to explore the dose-response mechanism of prolonged noise-induced audiological dysfunction and cochlear synaptic degeneration. In our results, mice repeatedly exposed to relatively low-intensity noise (88, 91, and 94 dB SPL) showed few changes on auditory brainstem response (ABR), ribbon synapses, or MOC efferent synapses. Notably, repeated moderate-intensity noise exposures (97 and 100 dB SPL) not only caused hearing threshold shifts and the inner hair cell ribbon synaptopathy but also impaired MOC efferent synapses, which might contribute to complex patterns of damages on cochlear function and morphology. However, repeated high-intensity (103 and 106 dB SPL) noise exposures induced PTSs mainly accompanied by damages on cochlear amplifier function of outer hair cells and the inner hair cell ribbon synaptopathy, rather than the MOC efferent synaptic degeneration. Moreover, we observed a frequency-dependent vulnerability of the repeated acoustic trauma-induced cochlear synaptic degeneration. This study provides a sight into the hypothesis that noise-induced cochlear synaptic degeneration involves both afferent (ribbon synapses) and efferent (MOC terminals) pathology. The pattern of dose-dependent pathological changes induced by repeated noise exposure at various intensities provides a possible explanation for the complicated cochlear synaptic degeneration in humans. The underlying mechanisms remain to be studied in the future.

Noise exposure has traditionally been considered the primary risk factor for hearing loss. However, ototoxicants commonly found in occupational settings could affect hearing loss independently, additively, or synergistically when combined with noise exposures. The purpose of this investigation was to determine the combined effect of metal and solvent ototoxicants, continuous noise, and impulse noise on hearing loss. Noise and ototoxicant exposure and pure-tone audiometry results were analyzed for U.S. Air Force personnel (n = 2,372) at a depot-level aircraft maintenance activity at Tinker Air Force Base, Oklahoma. Eight similar exposure groups based on combinations of ototoxicant and noise exposure were created including: (1) Continuous noise (reference group); (2) Continuous noise + Impulse noise; (3) Metal exposures + Continuous noise; (4) Metal exposures + Continuous noise + Impulse noise; (5) Solvent exposure + Continuous noise; (6) Solvent exposures + Continuous noise + Impulse noise; (7) Metal exposure + Solvent exposures + Continuous noise; and (8) Metal exposure + Solvent exposures + Continuous noise + Impulse noise. Hearing loss was assessed at center octave band frequencies of 500-6,000 Hz and using National Institute for Occupational Safety and Health Standard Threshold Shift (STS) criteria. Hearing changes were significantly worse at 2,000 Hz in the Metal exposure + Solvent exposure + Continuous noise group compared to the Continuous noise only reference group (p = 0.023). The Metal exposure + Solvent exposure + Continuous noise group had a significantly greater relative risk (RR) of 2.44; 95% CI [1.24, 4.83] for developing an STS at 2,000 Hz. While not statistically significant, the Solvent exposure + Continuous noise group had a RR of 2.32; 95%CI [1.00, 5.34] for developing an STS at 1,000 Hz. These results indicate that noise exposure may dominate hearing loss at ≥3,000 Hz while combined effects of concomitant exposure to ototoxic substances and noise are only noticeable at ≤2,000 Hz. These results also suggest combined exposures to ototoxicants and noise presents a greater hearing loss risk than just noise.

OBJECTIVES Over the past decade, U.S. Department of Defense and Veterans Affairs audiologists have reported large numbers of relatively young adult patients who have normal to near-normal audiometric thresholds but who report difficulty understanding speech in noisy environments. Many of these service members also reported having experienced exposure to explosive blasts as part of their military service. Recent studies suggest that some blast-exposed patients with normal to near-normal-hearing thresholds not only have an awareness of increased hearing difficulties, but also poor performance on various auditory tasks (sound source localization, speech recognition in noise, binaural integration, gap detection in noise, etc.). The purpose of this study was to determine the prevalence of functional hearing and communication deficits (FHCD) among healthy Active-Duty service men and women with normal to near-normal audiometric thresholds. DESIGN To estimate the prevalence of such FHCD in the overall military population, performance of roughly 3400 Active-Duty service members with hearing thresholds mostly within the normal range were measured on 4 hearing tests and a brief 6-question survey to assess FHCD. Subjects were subdivided into 6 groups depending on the severity of the blast exposure (3 levels: none, far away, or close enough to feel heat or pressure) and hearing thresholds (2 levels: audiometric thresholds of 20 dB HL or better, slight elevation in 1 or more thresholds between 500 and 4000 Hz in either ear). RESULTS While the probability of having hearing difficulty was low (≈4.2%) for the overall population tested, that probability increased by 2 to 3 times if the service member was blast-exposed from a close distance or had slightly elevated hearing thresholds (>20 dB HL). Service members having both blast exposure and mildly elevated hearing thresholds exhibited up to 4 times higher risk for performing abnormally on auditory tasks and more than 5 times higher risk for reporting abnormally low ratings on the subjective questionnaire, compared with service members with no history of blast exposure and audiometric thresholds ≤20 dB HL. Blast-exposed listeners were roughly 2.5 times more likely to experience subjective or objective hearing deficits than those with no-blast history. CONCLUSIONS These elevated rates of abnormal performance suggest that roughly 33.6% of Active-Duty service members (or approximately 423,000) with normal to near-normal-hearing thresholds (i.e., H1 profile) are at some risk for FHCD, and about 5.7% (approximately 72,000) are at high risk, but are currently untested and undetected within the current fitness-for-duty standards. Service members identified as "at risk" for FHCD according to the metrics used in the present study, in spite of their excellent hearing thresholds, require further testing to determine whether they have sustained damage to peripheral and early-stage auditory processing (bottom-up processing), damage to cognitive processes for speech (top-down processing), or both. Understanding the extent of damage due to noise and blast exposures and the balance between bottom-up processing deficits and top-down deficits will likely lead to better therapeutic strategies.

Purpose In this study, the efficacy and feasibility of melatonin in young children with and without comorbidities, undergoing auditory brainstem response audiometry (ABR) was evaluated. The aim of this study was primarily to evaluate the use of melatonin for ABR investigations in children with comorbidities. Second, the efficacy of melatonin was evaluated based on several factors like sleep-onset latency, sleep duration, frequency of awakenings as well as adverse events. Methods Click-induced ABR tests were performed at the outpatient clinic between January, 2018 and August, 2020. Investigations were considered successful when binaural testing was completed. A dose of melatonin depending on age, 5 mg for children younger than 6 years and 10 mg if older than 6 years, was administered after placement of electrodes. Results 131 children were included in this study. 87% of all ABR investigations were performed successfully. Comorbidities such as neurodevelopmental disorders or developmental delays were present in 70% of all children. There was no significant difference in age (p = 0.36) or gender (p = 0.97) between the success and failed group. In addition, comorbidities were equally distributed between both groups. Mean sleep duration was 38 (SD 21) min and sleep-onset latency was 28 (SD 20) min No adverse events were documented. Conclusion Melatonin is effective for ABR examinations in infants and children with and without comorbidities. Furthermore, it allows for sequential testing in those at risk for progressive hearing loss. Clear instructions to caregivers and expertise of audiologists are a prerequisite for optimal outcomes.

A model-based determination of the average supra-threshold (���distortion���) component of hearing impairment which limits the benefit of hearing aid amplification. Published speech recognition thresholds (SRTs) were predicted with the framework for auditory discrimination experiments (FADE), which simulates recognition processes, the speech intelligibility index (SII), which exploits frequency-dependent signal-to-noise ratios (SNR), and a modified SII with a hearing-loss-dependent band importance function (PAV). Their attenuation-component-based prediction errors were interpreted as estimates of the distortion component. Unaided SRTs of 315 hearing-impaired ears measured with the German matrix sentence test in stationary noise. Overall, the models showed root-mean-square errors (RMSEs) of 7 dB, but for steeply sloping hearing loss FADE and PAV were more accurate (RMSE = 9 dB) than the SII (RMSE = 23 dB). Prediction errors of FADE and PAV increased linearly with the average hearing loss. The consideration of the distortion component estimate significantly improved the accuracy of FADE���s and PAV���s predictions. The supra-threshold distortion component���estimated by prediction errors of FADE and PAV���seems to increase with the average hearing loss. Accounting for a distortion component improves the model predictions and implies a need for effective compensation strategies for supra-threshold processing deficits with increasing audibility loss.

Objective Investigation of long-term safety and performance of an active, transcutaneous bone conduction implant in adults and children up to 36 months post-implantation. Study design Prospective, single-subject repeated-measures design. Setting Otolaryngology departments of eight German and Austrian hospitals.*†‡§||¶#**†† Affiliations listed above that did not participate in the study.‡‡§§||||¶¶. Patients Fifty seven German-speaking patients (49 adults and eight children) suffering from conductive or mixed hearing loss, with an upper bone conduction threshold limit of 45 dB HL at frequencies between 500 and 3000 Hz. Intervention Implantation of the Bonebridge transcutaneous bone conduction hearing implant (tBCI). Main outcome measures Patients' audiometric pure tone averages (PTA4) (0.5, 1, 2, 4 kHz) thresholds (air conduction, bone conduction, and sound field) and speech perception (word recognition scores [WRS] and speech reception thresholds [SRT50%]) were tested preoperatively and up to 36 months postoperatively. Patients were also monitored for adverse events and administered quality-of-life questionnaires. Results Speech perception (WRS: pre-op: 17.60%, initial activation [IA]: 74.23%, 3M: 83.65%, 12M: 83.46%, 24M: 84.23%, 36M: 84.42%; SRT50%: pre-op: 65.56 dB SPL, IA: 47.67 dB SPL, 3M: 42.61 dB SPL, 12M: 41.11 dB SPL, 24M: 41.74 dB SPL, 36M: 42.43 dB SPL) and sound field thresholds (pre-op: 57.66 dB HL, IA: 33.82 dB HL, 3M: 29.86 dB HL, 12M: 28.40 dB HL, 24M: 28.22 dB HL, 36M: 28.52 dB HL) improved significantly at all aided postoperative visits. Air and bone conduction thresholds showed no significant changes, confirming preservation of patients' residual unaided hearing. All adverse events were resolved by the end of the study. Conclusions Safety and performance of the tBCI was demonstrated in children and adults 36 months postoperatively.

A fundamental property of mammalian hearing is the conversion of sound pressure into a frequency-specific place of maximum vibration along the cochlear length, thereby creating a tonotopic map. The tonotopic map makes possible systematic frequency tuning across auditory-nerve fibers, which enables the brain to use pitch to separate sounds from different environmental sources and process the speech and music that connects us to people and the world. Sometimes a tone has a different pitch in the left and right ears, a perceptual anomaly known as diplacusis. Diplacusis has been attributed to a change in the cochlear frequency-place map, but the hypothesized abnormal cochlear map has never been demonstrated. Here we assess cochlear frequency-place maps in guinea-pig ears with experimentally-induced endolymphatic hydrops, a hallmark of Ménière’s disease. Our findings are consistent with the hypothesis that diplacusis is due to an altered cochlear map. Map changes can lead to altered pitch, but the size of the pitch change is also affected by neural synchrony. Our data show that the cochlear frequency-place map is not fixed but can be altered by endolymphatic hydrops. Map changes should be considered in assessing hearing pathologies and treatments.

The auditory brainstem response (ABR) to stimulus onset has been extensively used to investigate dolphin hearing. The mechanisms underlying this onset response have been thoroughly studied in mammals. In contrast, the ABR evoked by sound offset has received relatively little attention. To build upon previous observations of the dolphin offset ABR, a series of experiments was conducted to (1) determine the cochlear places responsible for response generation and (2) examine differences in response morphologies when using toneburst versus noiseburst stimuli. Measurements were conducted with seven bottlenose dolphins (Tursiops truncatus) using tonebursts and spectrally "pink" broadband noisebursts, with highpass noise used to limit the cochlear regions involved in response generation. Results for normal-hearing and hearing-impaired dolphins suggest that the offset ABR contains contributions from at least two distinct responses. One type of response (across place) might arise from the activation of neural units that are shifted basally relative to stimulus frequency and shares commonalities with the onset ABR. A second type of response (within place) appears to represent a "true" offset response from afferent centers further up the ascending auditory pathway from the auditory nerve, and likely results from synchronous activity beginning at or above the cochlear nucleus.

OBJECTIVES On the basis of the data from school-aged children, there is consistent evidence that there is a prolonged course of auditory development for perceiving speech embedded in competing background sounds. Furthermore, age-related differences are prolonged and pronounced for a two-talker speech masker compared to a speech-shaped noise masker. However, little is known about the course of development during the toddler and preschool years because it is difficult to collect reliable behavioral data from this age range. The goal of this study was to extend our lower age limit to include toddlers and preschoolers to characterize the developmental trajectory for masked speech detection thresholds across childhood. DESIGN Participants were 2- to 15-year-old children (n = 67) and adults (n = 17), all with normal hearing. Thresholds (71%) were measured for detecting a two-syllable word embedded in one of two maskers: speech-shaped noise or two-talker speech. The masker was presented at 55 dB SPL throughout testing. Stimuli were presented to the left ear via a lightweight headphone. Data were collected using an observer-based testing method in which the participant's behavior was judged by an experimenter using a two-interval, two-alternative testing paradigm. The participant's response to the stimulus was shaped by training him/her to perform a conditioned play-based response to the sound. For children, receptive vocabulary and working memory were measured. Data were fitted with a linear regression model to establish the course of development for each masker condition. Appropriateness of the test method was also evaluated by determining if there were age-related differences in training data, inter-rater reliability, or slope or upper asymptote estimates from pooled psychometric functions across different age groups. RESULTS Child and adult speech detection thresholds were poorer in the two-talker masker than in the speech-shaped noise masker, but different developmental trajectories were seen for the two masker conditions. For the speech-shaped noise masker, threshold improved by about 5 dB across the age span tested, with adult-like performance being reached around 10 years of age. For the two-talker masker condition, thresholds improved by about 7 dB between 2.5 and 15 years. However, the linear fit for this condition failed to achieve adult-like performance because of limited data from teenagers. No significant age-related differences were seen in training data, probe hit rate, or inter-rater reliability. Furthermore, slope and upper asymptote estimates from pooled psychometric functions were similar across different child age groups. CONCLUSIONS Different developmental patterns were seen across the two maskers, with more pronounced child-adult differences and prolonged immaturity during childhood for the two-talker masker relative to the speech-shaped noise masker. Our data do not support the idea that there is rapid improvement of masked speech detection thresholds between 2.5 and 5 years of age. This study also highlights that our observer-based method can be used to collect reliable behavioral data from toddlers and preschoolers-a time period where we know little about auditory development.

Background Vitiligo is characterized by the destruction of functional melanocytes in the skin. This destruction can target melanocytes anywhere in the body, in turn affecting the function of the organs in which the affected melanocytes reside. Melanocytes in the skin, uveal tract and ear are similar in their physiology and morphology, and share a common embryological origin. Aim To study the association of vitiligo with ocular and auditory abnormalities. Methods This case-control study was carried out on 40 patients with vitiligo and 20 healthy controls (HCs). All patients and HCs underwent auditory examination (otoscopic examination and immittance audiometry to assess middle ear pressure and exclude tympanic membrane perforation; pure tone audiometry to assess peripheral hearing sensitivity; and transient evoked otoacoustic emissions to assess central hearing ability) and standard ocular examination including visual acuity test, slit lamp biomicroscopy and optical coherence tomography. Results Compared with controls, there was a significantly higher prevalence of hearing loss and ocular abnormalities in patients with vitiligo but no significant difference in visual acuity. Conclusion Vitiligo is a systemic disease that can be associated with impairment of melanocyte function organs other than the skin, including the eyes and ears. The function of auditory melanocytes is related to the hearing process and thus their destruction could lead to hearing impairment. By contrast, ocular melanocytes do not play a direct role in detection or transfer of visual information, and thus should not affect vision. Vitiligo may be associated with ocular abnormalities and hearing loss.

Objective To report the proportion of subjects successfully fit with combined electroacoustic stimulation (EAS) compared with those with preserved hearing (HP) after cochlear implantation (CI). In addition, to 1) report the trends in HP and EAS fit rates over time and 2) identify and characterize those patients who preferred the electric only condition. Study design Retrospective chart review. Setting Tertiary referral center. Patients Two hundred five postlingually deafened adults with bilateral SNHL and a preoperative low-frequency pure-tone average 80 dB HL or better in the ear to be implanted. Interventions Subjects underwent CI from 2013 to 2018 with routine pre- and postoperative audiometric testing performed at 6- and 12-months. Main outcome measures Percentage of patients fit with EAS, low-frequency pure-tone average, and threshold shift. Results Overall, 141 patients (78.6%) had HP at activation and 42.6% were fit with EAS. Rates of EAS fitting improved from 36.4% in 2013 to 69.0% in 2018. 93.5% of patients had hearing preserved in 2018 compared with 57.9% in 2013. Six patients rejected EAS after a trial period either because of discomfort or poor sound quality. Eight patients had EAS removed because of loss of aidable hearing over time (between activation to 12 mo). Conclusions Despite the high percentages of HP in the literature, EAS may be under-utilized in the adult CI population. Moving toward a universal definition of HP across institutions may better represent the potential for EAS fitting and a clinical measure capable of identifying patients best suited to benefit from EAS.

Background Lichen planus (LP), which affects skin, nails, hair, and mucosal surfaces, is a chronic, autoimmune, and inflammatory disease, and autoimmune diseases may affect the inner ear. Aims This study aims to investigate hearing and inner ear functions of the LP patients. Patients/methods The present study was formed by 49 patients who were clinically and histopathologically diagnosed with LP and did not receive any treatment. The healthy group consisted of 52 healthy individuals. Pure tone audiometry (PTA) and distortion product otoacoustic emission tests were used in the hearing evaluation. Results At frequencies of 1, 2, 4, 6, and 8 kHz in the right ear and 0.5, 1, 2, 4, 6, and 8 kHz in the left ear in PTA, the lichen group's hearing thresholds were higher than the healthy group's. Upon comparing the hearing thresholds of LP patients with oral mucosa involvement and LP patients without oral mucosa involvement, there were significant differences between the groups at 1, 4, and 8 kHz in the right ear and at 0.25, 0.5, 2, 4, 6, and 8 kHz in the left ear. Conclusion Because of the increasing hearing thresholds, we think that hearing and inner ear functions of LP patients, particularly with oral mucosal involvement, are negatively affected.

OBJECTIVES To characterize the relationship between cochlear duct length (CDL) and initial hearing preservation among cochlear implant recipients of a fully inserted 31.5 mm flexible lateral wall electrode array. STUDY DESIGN Retrospective review. SETTING Tertiary academic referral center. PATIENTS Adult cochlear implant recipients who presented preoperatively with unaided hearing detection thresholds of ≤ 65 dB HL at 125 Hz and underwent cochlear implantation with a 31.5 mm flexible lateral wall array. INTERVENTION Cochlear implantation with a hearing preservation surgical approach. MAIN OUTCOME MEASURES Computed tomography was reviewed to determine CDL. Hearing preservation was characterized by the shift in low-frequency pure-tone average (LFPTA; 125, 250, and 500 Hz), and shift in individual unaided hearing detection thresholds at 125, 250, and 500 Hz. RESULTS Nineteen patients met the criteria for inclusion. The mean CDL was 34.2 mm (range: 30.8-36.5 mm). Recipients experienced a mean LFPTA shift of 27.6 dB HL (range: 10-50 dB HL). Significant, negative correlations were observed between CDL and smaller threshold shifts at individual frequencies and LFPTA (p ≤ 0.048). CONCLUSION A longer CDL is associated with greater likelihood of preserving low-frequency hearing with long arrays. Low-frequency hearing preservation is feasible with fully inserted long flexible arrays within the initial months after cochlear implantation. Preoperative measurement of CDL may facilitate a more individualized approach in array selection to permit optimal cochlear coverage while enhancing hearing preservation outcomes.

Hearing deficits impact on the communication with the external world and severely compromise perception of the surrounding. Deafness can be caused by particular mutations in the neuroplastin (Nptn) gene, which encodes a transmembrane recognition molecule of the immunoglobulin (Ig) superfamily and plasma membrane Calcium ATPase (PMCA) accessory subunit. This study investigates whether the complete absence of neuroplastin or the loss of neuroplastin in the adult after normal development lead to hearing impairment in mice analyzed by behavioral, electrophysiological, and in vivo imaging measurements. Auditory brainstem recordings from adult neuroplastin-deficient mice (Nptn−/−) show that these mice are deaf. With age, hair cells and spiral ganglion cells degenerate in Nptn−/− mice. Adult Nptn−/− mice fail to behaviorally respond to white noise and show reduced baseline blood flow in the auditory cortex (AC) as revealed by single-photon emission computed tomography (SPECT). In adult Nptn−/− mice, tone-evoked cortical activity was not detectable within the primary auditory field (A1) of the AC, although we observed non-persistent tone-like evoked activities in electrophysiological recordings of some young Nptn−/− mice. Conditional ablation of neuroplastin in Nptnlox/loxEmx1Cre mice reveals that behavioral responses to simple tones or white noise do not require neuroplastin expression by central glutamatergic neurons. Loss of neuroplastin from hair cells in adult NptnΔlox/loxPrCreERT mice after normal development is correlated with increased hearing thresholds and only high prepulse intensities result in effective prepulse inhibition (PPI) of the startle response. Furthermore, we show that neuroplastin is required for the expression of PMCA 2 in outer hair cells. This suggests that altered Ca2+ homeostasis underlies the observed hearing impairments and leads to hair cell degeneration. Our results underline the importance of neuroplastin for the development and the maintenance of the auditory system.