Increased Hearing Thresholds Research Articles

Perfusion Steroid via Ventilation Tube as Salvage Treatments for Sudden Sensorineural Hearing Loss.

Objectives: Intratympanic steroid injection (ISI) for sudden sensorineural hearing loss (SSNHL) is a relatively popular and effective method, but there is no standardized method for intratympanic steroids for the treatment of SSNHL and no consensus on how to deliver steroids to the middle ear. The purpose of this study was to compare 2 means of intratympanic steroid delivery as therapy for SSNHL. Methods: A retrospective chart review was performed for the period from November 2018 to October 2022 at our Department of Otorhinolaryngology-Head and Neck Surgery. Sixty patients with profound SSNHL who have failed initial steroid therapy were divided into the continuously transtympanic steroid perfusion (TSP) therapy and the intermittent ISI therapy. Results: Posttreatment pure-tone average was 60.3 ± 18.2 dB in the TSP group and 67.5 ± 22.6 dB in the ISI group, 70.0% of subjects in the TSP group, and 46.7% of subjects in the ISI group had improved by 15 dB or more after the therapy. The increased hearing threshold of the TSP group (24.6 ± 14.1 dB) was better than the ISI group (16.6 ± 14.9 dB), and the hearing recovery was significantly different (P < .05) in the 2 groups. Besides the hearing improvement was most obvious in low-frequency areas in the TSP group, the most significant hearing improvement was at 250 Hz, reaching 30.8 ± 3.3 dB. Conclusions: In SSNHL patients who have failed initial steroid therapy, TSP therapy via a ventilation tube can achieve good hearing outcomes and serve as a salvage therapy for patients with SSNHL.

Hearing, Balance, and Mortality: Sex-Specific Patterns in a Longitudinal Study.

Assess the association of hearing on sex-specific overall mortality and death from acute cardiovascular disease and evaluate if these effects are modulated by postural balance. Cohort study. Otolaryngology department at an academic hospital. Patients underwent standard clinical examination, laboratory examination including stabilometry and audiometry. Pure tone average on the best hearing ear was calculated from 0.5, 1, 2, and 3 kHz. Cause of death was retrieved from the Norwegian Cause of Death Registry. A total of 1036 patients (58.8% women) were followed for 26 ± 3 years. In Cox regression analyses for overall mortality adjusted for age, past medical history, and vestibular disease, 10 dB increase in hearing threshold was associated with a 14% increase in mortality among men (hazard ratio 95% confidence interval: 1.02-1.28, P = .02), but no significant association was seen between hearing and mortality in women (0.92-1.15, P = .60). The same analyses for acute cardiovascular death found that a 10 dB increase in hearing threshold was associated with a 57% increase in hazard ratio in men (1.21-2.05, P < .001), but no significant effect of hearing on survival was seen in women (P = .71). Adjusting for postural balance did not change the association between hearing and mortality. This study finds hearing threshold is associated with overall mortality and acute cardiovascular death among men, with no such association observed among women. Our findings indicate important differences between men and women and suggest that such differences should be taken into consideration in audiological research.

Microplastic polyethylene induced inner ear dysfunction in murine model

While the hazardous effects of microplastics (MPs) are increasingly reported, it remains uncertain if MPs induce inner ear dysfunction. Nonetheless, prevalence of inner ear dysfunction was observed across all age groups. In this study, we investigated whether MP polyethylene affect inner ear function in a murine model. To detect hearing loss and balance defect after polyethylene (PE) exposure, we evaluated hearing threshold levels, assessed cerebral glucose metabolism, conducted transcriptome analysis, and performed behavioral studies. C57BL/6 J mice (5-week-old) were grouped into control (n = 10) and PE-fed groups (n = 10). Mice were orally administered 100 ppm/100 μL (equivalent to 10 μg) of PE every day for 4 months. We identified the accumulation of PE in the cochlea and vestibular region. The fragmented PE in inner ear was 3.00 ± 0.38 µm in size; the administered PE concentration was 1.14 ± 1.06 mg/g. Fourier transform infrared spectrometry confirmed that the properties of the MP were identical with those of PE fed to the mice. Transcriptomic analysis showed up-regulation of PER1, NR4A3 and CEBPB at the PE exposed inner ear tissue and it was confirmed using qRT-PCR, western blotting, and immunofluorescence staining. We observed abnormalities in balance related behavior assessment in the PE group. Exposure to PE increased the hearing thresholds and decreased glucose metabolism in the bilateral lateral entorhinal cortex, right primary auditory cortex, and right secondary auditory cortex. We can conclude that PE exposure induced inner ear dysfunction such as hearing loss and balance disorder.

Hearing screening in video game players with headphones use

Background: Hearing loss due to noise can cause by entertainment activities. Loud noise resulting from use of earphones with excessive volume and for long periods threatens the safety of the user's hearing. Purpose: To determine the hearing function of video game players who use headphones. Methods: This research is a descriptive study with a cross-sectional design. Hearing function of the players were carried out using pure tone audiometry. Results: Total of 56 subjects were male (100%) and 66.1% subjects had used headphones for &lt;12 months, 7.1% for 12-24 months and 26.8% for &gt;24 months. As many as 87.5% subjects were exposed to headphone noise for &lt;3 hours per day, 10.7% subjects for 4-6 hours per day and 1.8% for &gt;6 hours per day. The volume level of headphones gamers was mostly set at 6 (39.3%). Based on pure tone audiometry, all subjects had normal hearing thresholds at low frequencies (500Hz and 1000Hz) and medium frequencies (2000Hz and 4000 Hz). Only 3 subjects (5%) had an increase of hearing threshold at high frequencies (6000Hz and 8000Hz). Conclusion: The hearing thresholds for each ear in video game players who use headphones based on frequency groups were identified in this study. An increase in hearing threshold in gamers could be an early sign of hearing loss, then hearing conservation education program should be considered for active gamers.

Evaluation of Subjective Tinnitus Severity and Distortion Product Otoacoustic Emissions and Extended High-Frequency Audiometry.

Tinnitus is a multifactorial phenomenon with quality-of-life detriments for those affected by it. We aim to establish a relationship between subjective tinnitus severity with objective audiometric data in the extended high frequency (EHF) from 9 to 16 khz and with distortion product otoacoustic emissions (DPOAE). We hypothesize that severe subjective tinnitus as measured by the Tinnitus Handicap Inventory (THI) does not correlate with increased hearing thresholds in the EHF range. Prospective. Single Tertiary Care Center. Patients identified with tinnitus and normal hearing thresholds within standard frequency range (250-8000 Hz) were consented for participation. Those with underlying otologic disease, trauma, radiotherapy, or ototoxic drug use were excluded. The THI questionnaire was given to eligible patients and audiometric test results were collected. THI scores were categorized by severity groups. An n = 20 to 30 was determined to have an effect size of 0.7 with a significance level of P = .05. THI and audiometric data were collected for 38 patients and categorized into mild (n = 18, 47.4%), moderate (n = 8, 21.1%), slight (n = 7, 18.4%), and severe (n = 5, 13.2%) tinnitus severity groups. Mean THI score was 32.3 ± 19.6 with a statistically significant difference in scores by assigned THI severity group (P < .01). There were no significant differences or linear relationship among hearing thresholds in EHF range or DPOAE stratified by subjective tinnitus group (P = .49, r2 = 0.10) CONCLUSION: Subjective tinnitus severity is not predictive of audiometric outcomes. This finding can be used as a counseling tool to help tinnitus patients manage symptoms, expectations, and overall treatment outcomes.

Analysis between Demographic Factors, Chronic Conditions and Its Association with Increased Hearing Threshold On Factory Workers Exposed to Noise: A Cross Sectional Study in 2022

Analysis between Demographic Factors, Chronic Conditions and Its Association with Increased Hearing Threshold On Factory Workers Exposed to Noise: A Cross Sectional Study in 2022

Age-Related Deficits in Binaural Hearing: Contribution of Peripheral and Central Effects.

Pure-tone audiograms often poorly predict elderly humans' ability to communicate in everyday complex acoustic scenes. Binaural processing is crucial for discriminating sound sources in such complex acoustic scenes. The compromised perception of communication signals presented above hearing threshold has been linked to both peripheral and central age-related changes in the auditory system. Investigating young and old Mongolian gerbils of both sexes, an established model for human hearing, we demonstrate age-related supra-threshold deficits in binaural hearing using behavioral, electrophysiological, anatomical, and imaging methods. Binaural processing ability was measured as the binaural masking level difference (BMLD), an established measure in human psychophysics. We tested gerbils behaviorally with "virtual headphones," recorded single-unit responses in the auditory midbrain and evaluated gross midbrain and cortical responses using positron emission tomography (PET) imaging. Furthermore, we obtained additional measures of auditory function based on auditory brainstem responses, auditory-nerve synapse counts, and evidence for central inhibitory processing revealed by PET. BMLD deteriorates already in middle-aged animals having normal audiometric thresholds and is even worse in old animals with hearing loss. The magnitude of auditory brainstem response measures related to auditory-nerve function and binaural processing in the auditory brainstem also deteriorate. Furthermore, central GABAergic inhibition is affected by age. Because the number of synapses in the apical turn of the inner ear was not reduced in middle-aged animals, we conclude that peripheral synaptopathy contributes little to binaural processing deficits. Exploratory analyses suggest increased hearing thresholds, altered binaural processing in the brainstem and changed central GABAergic inhibition as potential contributors.

A study of auditory acuity in patients with essential hypertension using pure tone audiometry

Background: The ability to communicate is a crucial aspect of human life and auditory sense is very important for communication of any kind. It has been hypothesized that hypertension is an independent risk factor for hearing loss is arterial hypertension. It is hypothesised that hypertension causes the degeneration of inner ear due to alteration in microcirculation. This study is undertaken to identify the role of hypertension in auditory acuity. Aims and Objectives: The aim of the study was to assess the association between high blood pressure and hearing function, after excluding the influence of noise pollution on hearing impairment and to see the association of duration of hypertension with hearing impairment, by performing pure tone audiometric tests on normotensives and hypertensives. Materials and Methods: 50 hypertensives visiting Hesaraghatta PHC and 50 normotensives residing in the same area were chosen for the study. After selecting the subjects from appropriate inclusion-exclusion criteria, informed consent was taken. Then blood pressure was measured followed by audiometric assessment for hearing acuity in each using standard guidelines. The results were compiled and statistically analysed. Results: Hypertensives have a higher threshold in all frequencies for both air conduction and bone conduction. Significant P-values were found in both ears for all frequencies in both air conduction and bone conduction in both ears. Thresholds are increased but were within normal limits since cases are on treatment, resulting in mild hypertension. Conclusions: There was a significant increase in hearing thresholds at all frequencies in hypertensives than normotensives. In the current study, no significant correlation was found between duration of hypertension and auditory thresholds.

Hearing impairment and risk of dementia in The HUNT Study (HUNT4 70+): a Norwegian cohort study

Hearing impairment is strongly associated with future dementia. No studies have reported objectively measured hearing impairment in a cohort with a long period of follow-up (>20 years), and few have reported follow-up over 10 years. Hence, there is a need for high quality studies with sufficient follow-up time and data to account for reverse causality and confounding. We aimed to address this knowledge gap. This cohort study used individual participant data from The Trøndelag Health Study (HUNT) in Norway. All current residents aged at least 20 years in the former Norwegian Nord-Trøndelag County were invited to participate in four decennial surveys: HUNT1 (1984-1986), HUNT2 (1995-1997), HUNT3 (2006-2008), and HUNT4 (2017-2019) with individuals aged at least 70 years included in a substudy, known as HUNT4 70+. Here, we report the findings of this substudy. HUNT4 70+ comprised 7135 participants who were assessed for dementia using the Diagnostic and Statistical Manual of Mental Disorders 5 criteria and who had audiometry between 1996 and 1998. The primary objective was to investigate, with gold standard audiometric testing and dementia diagnostic assessment, whether hearing impairment was an independent risk factor for all-cause dementia. The secondary objective was to investigate if a risk also applied to Alzheimer dementia and non-Alzheimer dementia. We analysed the association using Poisson regression and adjusted for confounders. This study is registered with ClinicalTrials.gov (NCT04284384). At baseline, 1058 (15%) individuals had acquired hearing impairment with a hearing threshold of at least 25 decibel (dB) and, at follow-up, 1089 (15%) had dementia. In the total group, people with hearing impairment had a relative risk (RR) 1.04 (95% confidence interval (CI) 1.00-1.09) per 10dB increase in hearing thresholds. For individuals younger than 85 years at follow-up the RR was 1.12 (95% CI 1.05-1.21). Associations between hearing impairment and Alzheimer dementia and non-Alzheimer dementia were similar. There was no association for individuals aged at least 85 years. We found a moderate association between objectively measured hearing impairment and dementia in the younger age group (<85 years). The findings of no association in the older age group (≥85 years) might be due to the competing risk of death. The present study adds to the literature showing that acquired hearing impairment is a risk for dementias over a period which is too long for reverse causation, and with thorough consideration of confounders. Further research is needed to investigate associations between the different aetiologies of hearing loss and dementia subtypes, and risk differences for sexes. The Norwegian National Centre for Ageing and Health with a grant from Health South-East.

The significance of serum Klotho to hearing loss: a potential protector under noise pollution.

The issue of hearing protection in the presence of noise pollution is of great importance in the fields of environmental science and clinical medicine. Currently, the clinical significance of Klotho in relation to hearing has not been revealed. The aim of this study was to examine the correlation between serum Klotho levels and Pure Tone Average (PTA) hearing thresholds among individuals in the U.S.. The analysis involved a sample of 1,781 individuals aged 20 to 69, obtained from the 2007-2012 National Health and Nutrition Examination Survey. Various methods were utilized for the analysis, including univariate and multivariate linear regression, stratified analysis, smooth curve fitting, a two-segment linear regression model, and log-likelihood ratio analysis. The results of the univariate analysis indicated that serum Klotho concentration, age, education level, hypertension, diabetes, and smoking all exhibited a significant influence on PTAs. After adjusting for potential confounding factors, it was observed that a decrease in serum Klotho was significantly associated with PTA thresholds at low frequency (β = -0.002; 95% CI: -0.003, -0.001; P = 0.004), speech frequency (β = -0.002; 95% CI: -0.003, -0.001; P = 0.007), and high frequency (β = -0.002; 95% CI: -0.003, -0.001; P = 0.045). Specifically, for every 1pg/ml decrease in serum Klotho concentration, the PTAs increased by 0.002dB. Moreover, age and gender-specific analyses revealed significant associations. For individuals aged 59-69, a significant association was found between serum Klotho concentration and high-frequency PTA (β = -4.153; 95% CI: -7.948, -0.358; P = 0.032). Additionally, among females, significant associations were observed between serum Klotho concentration and speech-frequency PTA (β = -1.648, 95% CI: -3.197, -0.099; P = 0.037) as well as high-frequency PTA (β = -3.046; 95% CI: -5.319, -0.772; P = 0.009). Finally, the results of smooth curve fitting and threshold effect analyses indicated a potential negative linear correlation between serum Klotho concentration and PTA thresholds. In conclusion, a lower level of serum Klotho was found to be associated with increased hearing thresholds, particularly among the elderly population. This finding has significant implications for the prevention and treatment of hearing damage.

The Effects of Noise Intensity and Duration of Exposure on Hearing Threshold of Students in Vocational High School 2 Banda Aceh

Background: Noise-induced hearing loss is caused by loud and continuous of noise exposure for a long time. Vocational high school students are a population at high risk of noise-induced hearing loss. This is due to exposure to noise from machines or practicum tools. The noise intensity from practicum tools or machines often exceeds the permissible threshold. Objective: To determine the effect of intensity and duration of noise exposure on hearing thresholds in students of Vocational high school 2 (SMKN 2) Banda Aceh. Method: This type of research is an observational analytic with a cross sectional design. The research sample was students of class XI and XII in the engineering and automotive department who were willing to participate in the research. The samples were interviewed and subjected to otoscopic and audiometric examinations. Room noise was rated with sound level meter. Results: 121 samples that met the inclusion criteria of this study. The majority of the sample in this study were 16 years old (47.9%), male (100%), were in the engineering department (75.2%), had never used ear protection (93.4%), were exposed to noise for 4-6 days a week (85.1%) and exposed to noise with an intensity of &gt;85dB (75.2%). In this study it was found that noise intensity and duration of exposure to noise had an effect on the increase in hearing threshold (p=0.001). Conclusion: There is a relationship between noise intensity and duration of noise exposure to the hearing threshold.

Protective Effects of Infliximab Against Kanamycin-Induced Ototoxicity in Rats.

To examine the protective effects of infliximab (INF) against kanamycin (KM)-induced hearing loss. Tumor necrosis factor α blockers can reduce cellular inflammatory reactions and decrease cell death. Thirty-six rats with normal hearing were randomly divided into six groups. The first group was injected with 400 mg/kg KM intramuscularly (IM), the second group with 7 mg/kg INF intraperitoneally (IP) and 400 mg/kg KM IM, the third group with 7 mg/kg INF IP and 200 mg/kg KM IM, and the fourth group with 1 mg/kg 6-methylprednisolone (MP) IP and 400 mg/kg KM IM. Group 5 was injected with 1 mg/kg MP IP and 200 mg/kg KM IM, and group 6 with saline IP once. Auditory brain-stem response (ABR) for hearing thresholds was performed on days 7 and 14. From the frozen sections of the cochlea, the area of the stria vascularis, the number of neurons in the spiral ganglion, the fluorescence intensity of hair cells (FIHC), postsynaptic density (PSD), and presynaptic ribbons (PSRs) were calculated. The KM-induced increase in hearing thresholds was detected on the 14th day. Hearing was only preserved in the group treated with INF after low-dose KM exposure but not in the groups that received high-dose KM. The FIHC, excitatory PSD, and PSR were preserved only in the INF-treated group after half-dose KM exposure. In MP groups, FIHC, excitatory PSD, and PSR were significantly lower than in the control group. Our results support that tumor necrosis factor-based inflammation may play a role in the ototoxicity mechanism.

Hearing Thresholds at High Frequencies: Age as a Predictor of Values.

Introduction The audiological evaluation has the main objective of determining the integrity of the auditory system. Pure tone audiometry is a standardized behavioral procedure that aims to investigate auditory thresholds to describe auditory sensitivity. Despite being recognized since the mid-1960s, high frequency audiometry is still little used and explored in clinical practice, and its use is more considered as an audiological monitoring tool or as a research tool. Objective To analyze the audiological thresholds of high frequency audiometry in normal hearing individuals, and to verify the predictive capacity of age in the auditory thresholds of high frequency audiometry. Methods This is a retrospective, cross-sectional, and quantitative study that was approved by the Research Ethics Committee under number 5.039.583/21. The procedures were: clinical evaluation, pure tone audiometry, acoustic immittance measurements, and high frequency audiometry. All data collected from the exams were tabulated in an Excel spreadsheet and analyzed using appropriate statistical tests in the Statistical Package Social Sciences software. Results A total of 980 medical records were analyzed. The right and left ears presented similar tonal hearing thresholds for the frequencies of 12 kHz and 16 kHz. The threshold variance of 29.8% in the 12 kHz frequency can be explained by the variance of age, while, for the frequency of 16 kHz, this percentage is of 46.4%. Conclusion For 12 kHz hearing thresholds, an increase of 1 year leads to a 0.66 dBHL increase in hearing threshold. For 16 kHz hearing thresholds, an increase of 1 year leads to a 1.02 dBHL increase in hearing threshold.

Hearing loss increases all-cause and cardiovascular mortality in middle-aged and older Chinese adults: the Dongfeng-Tongji Cohort Study.

We aimed to investigate the association between hearing loss and all-cause and cardiovascular disease (CVD) mortality, and whether the relationship could be modified by chronic conditions in middle-aged and older Chinese adults. We selected 18,625 participants who underwent audiometry in 2013 from the Dongfeng-Tongji Cohort conducted in China, and followed them until December 2018. Hearing loss was grouped as normal, mild, and moderate or severe by pure-tone hearing threshold at speech (0.5, 1, and 2kHz) and high frequency (4 and 8kHz). We applied Cox regression models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause and CVD mortality. Among the 18,625 participants, the mean age was 64.6 (range: 36.7-93.0) years, and 56.2% were women. A total of 1185 died, with 420 CVD deaths during a mean follow-up period of 5.5years. The adjusted HR for all-cause and CVD mortality increased gradually with the increasing hearing threshold (All p for trend < 0.05). Compared to participants with normal hearing at speech frequency, the adjusted HRs (95% CIs) of moderate or severe hearing loss were 1.42 (1.21-1.67), 1.44 (1.10-1.89), and 1.92 (1.21-3.04) for all-cause, CVD, and stroke mortality, respectively. While moderate or severe hearing loss at high frequency was only related to an increased risk of all-cause mortality (HR, 1.60; 95% CI, 1.18-2.17). The associations were generally consistent across subgroups (All p for interaction > 0.05). Additionally, individuals with a combination of moderate or severe hearing loss and occupational noise exposure, diabetes, or hypertension had higher risk of all-cause or CVD mortality, ranging from 1.45 to 2.78. In conclusion, hearing loss was independently associated with an increased risk of all-cause and CVD mortality, in a dose-response manner. Meanwhile, hearing loss and diabetes or hypertension could jointly increase the risk of all-cause and CVD mortality.

Evaluation of hearing limits post tympanoplasty in patients with chronic suppurative otitis media

Link of Video Abstract: https://youtu.be/Nr9MKgu2v2E Background: Chronic suppurative otitis media (CSOM) causes partial or complete damage to the tympanic membrane and ossicles, causing hearing loss in the form of conductive and mixed hearing loss with a decrease of up to 60 dB. This study aimed to evaluate the hearing threshold before and after tympanoplasty surgery in CSOM patients. Methods: This type of research was carried out in a retrospective descriptive manner. The materials in this study were the medical records of CSOM patients who underwent canal wall up (CWU) tympanoplasty and canal wall down (CWD) tympanoplasty at the outpatients of ear, nose, and throat – head and neck surgery (ENT-HNS) Otology Division Dr. Soetomo Hospital Surabaya for the period January 1, 2018 to December 31, 2018 with a total of 51 patients. This study analyzed with the Wilcoxon test. Results: The mean age was 30.96 years (51% female and 49% male). Postoperatively 40 (78.5%) patients experienced an increase in hearing threshold, 10 (19.6%) patients experienced a decrease and 1 (1.9%) patient remained. The average increase in air-bone gap (ABG) pre and post tympanoplasty surgery was 9.78 dB, from 38.92 dB to 29.14 dB. Conclusion: There was an increase in hearing threshold after tympanoplasty.

Systolic Blood Pressure and Objective Hearing Thresholds Among Japanese Middle-Aged Adults: A Facility-Based Retrospective Cohort Study.

Very few studies have compared the magnitude of the changes in the hearing thresholds at 1 and 4 kHz according to the systolic blood pressure (SBP). We investigated the effects of SBP on repeated measures of hearing threshold using pure-tone audiometry. This retrospective cohort study included 5,479 (for the analysis at 1 kHz) and 2,045 (for 4 kHz) individuals aged 50 to 59 years who underwent facility-based health checkups. A multivariable generalized linear mixed model was constructed for the analysis at 1 and 4 kHz. The mean follow-up durations were 30,262 and 7,454 person-years, respectively. The interaction of SBP and year was significantly associated with the change in hearing threshold in both analyses at 1 kHz (with estimated slope, 0.00080; 95% confidence interval, 0.00049-0.00110) and 4 kHz (with estimated slope, 0.0042; 95% confidence interval, 0.0028-0.0057). The 10-year changes in hearing threshold with baseline SBP of 110 and 140 mm Hg were 0.4 and 0.6 dB at 1 kHz and 1.0 and 2.3 dB at 4 kHz, respectively. Higher SBP was associated with an increased hearing threshold at both 1 and 4 kHz among middle-aged individuals.

Hearing loss and impaired short-term memory in an Alzheimer's disease mouse model of amyloid-beta pathology

Current evidence supports the link between hearing loss and Alzheimer's disease (AD). However, few studies report the hearing status of AD mice compared to wild-type mice. This study aimed to compare hearing thresholds and short-term memory (STM) performance of an AD (APPNL-G-F) mouse model of amyloid-beta (Aꞵ) pathology with C57BL/6 J and CBA/CaJ mice across age. The auditory brainstem response (ABR) test, using click and five tone-burst (TB) stimuli, was recorded at 2, 4, 6, 9, and 12 months. The novel object recognition (NOR) test, a measure of STM, was conducted at 6 and 12 months. While hearing thresholds were almost preserved in CBA/CaJ mice, they were not recorded at high frequencies with age in C57BL/6 J and AD mice, leading to island hearing (severe to profound hearing loss) at 9 and 12 months. AD mice showed increased hearing thresholds in TB8 and TB16 kHz at 6 and 9 months compared to C57BL/6 J mice. NOR findings were evidence of impaired STM in both C57BL/6 J and AD mice relative to CBA/CaJ mice, and a relationship was found between hearing thresholds and NOR measures in three groups. The findings were in support of the link between the degree of hearing loss and impaired STM.

Spectral Characteristics of Cardinal Vowels as Indicators of the Auditory Speech Feedback Control in Patients with Moderate and Moderately Severe Chronic Postlingual Sensorineural Hearing Loss

Chronic sensorineural hearing loss (SNHL) is characterized by an increase in hearing thresholds at basic speech frequencies, which implies the auditory speech feedback control worsening and, as a result, changes of speech characteristics. A hypothesis was tested that such worsening can manifest itself in an increase of F0, F1, F2 formants of speech vowel sounds in patients with moderate and moderately severe postlingual SNHL. Recordings of elicited speech were performed for young and middle age women (36–59 years): 7 women speakers with moderate SNHL who did not use hearing aids; 5 women speakers with moderately severe SNHL who were hearing aid users but were not using them during the recordings; a control group of 12 normally hearing women speakers. An assessment of F0, F1 and F2 of stressed vowels [a], [i], [u] and calculations of vowels’ centralization indices – vowel space area, vowel formant centralization ratio and the second formant ratio (F2i/F2u), were performed. All the studied spectral indices in groups of patients with postlingual SNHL were similar to those in the control group, no statistically reliable differences were revealed.

Resveratrol prevents hearing loss and a subregion specific- reduction of serotonin reuptake transporter induced by noise exposure in the central auditory system.

Prolonged or excessive exposure to noise can lead to hearing loss, tinnitus and hypersensitivity to sound. The effects of noise exposure on main excitatory and inhibitory neurotransmitter systems in auditory pathway have been extensively investigated. However, little is known about aberrant changes in neuromodulator systems caused by noise exposure. In the current study, we exposed 2-month-old mice to a narrow band noise at 116 dB SPL for 6 h or sham exposure, assessed auditory brainstem responses as well as examined the expression of serotonin reuptake transporter (SERT) in the cochlear nucleus (CN), inferior colliculus (IC), and primary auditory cortex (Au1) using immunohistochemistry. We found that noise exposure resulted in a significant increase in hearing thresholds at 4, 8, 16, 24, and 32 kHz, as well as led to a significant reduction of SERT in dorsal cochlear nucleus (DCN), dorsal IC (ICd), external IC (ICe), and Au1 layers I-IV. This reduction of SERT in these subregions of central auditory system was partially recovered 15 or 30 days after noise exposure. Furthermore, we examined efficacy of resveratrol (RSV) on hearing loss and loss of SERT induced by noise exposure. The results demonstrated that RSV treatment significantly attenuated threshold shifts of auditory brainstem responses and loss of SERT in DCN, ICd, ICe, and Au1 layers I-IV. These findings show that noise exposure can cause hearing loss and subregion-specific loss of SERT in the central auditory system, and RSV treatment could attenuate noise exposure-induced hearing loss and loss of SERT in central auditory system.

Cortical-brainstem interplay during speech perception in older adults with and without hearing loss.

Real time modulation of brainstem frequency-following responses (FFRs) by online changes in cortical arousal state via the corticofugal (top-down) pathway has been demonstrated previously in young adults and is more prominent in the presence of background noise. FFRs during high cortical arousal states also have a stronger relationship with speech perception. Aging is associated with increased auditory brain responses, which might reflect degraded inhibitory processing within the peripheral and ascending pathways, or changes in attentional control regulation via descending auditory pathways. Here, we tested the hypothesis that online corticofugal interplay is impacted by age-related hearing loss. We measured EEG in older adults with normal-hearing (NH) and mild to moderate hearing-loss (HL) while they performed speech identification tasks in different noise backgrounds. We measured α power to index online cortical arousal states during task engagement. Subsequently, we split brainstem speech-FFRs, on a trial-by-trial basis, according to fluctuations in concomitant cortical α power into low or high α FFRs to index cortical-brainstem modulation. We found cortical α power was smaller in the HL than the NH group. In NH listeners, α-FFRs modulation for clear speech (i.e., without noise) also resembled that previously observed in younger adults for speech in noise. Cortical-brainstem modulation was further diminished in HL older adults in the clear condition and by noise in NH older adults. Machine learning classification showed low α FFR frequency spectra yielded higher accuracy for classifying listeners' perceptual performance in both NH and HL participants. Moreover, low α FFRs decreased with increased hearing thresholds at 0.5-2 kHz for clear speech but noise generally reduced low α FFRs in the HL group. Collectively, our study reveals cortical arousal state actively shapes brainstem speech representations and provides a potential new mechanism for older listeners' difficulties perceiving speech in cocktail party-like listening situations in the form of a miss-coordination between cortical and subcortical levels of auditory processing.