Masking Level Research Articles

Why does tinnitus vary with naps? A polysomnographic prospective study exploring the somatosensory hypothesis

(1) BackgroundTinnitus, defined as the conscious awareness of a noise without any identifiable corresponding external acoustic source, can be modulated by various factors. Among these factors, tinnitus patients commonly report drastic increases of tinnitus loudness following nap sleep. Previous studies have suggested that this clinical pattern could be attributed to a somatosensory modulation of tinnitus. To our knowledge, no polysomnographic study has been carried out to assess this hypothesis. (2) MethodsFor this observational prospective study, 37 participants reporting frequent increases of tinnitus following naps were recruited. They participated to six full-polysomnography nap attempts over two days. Audiological and kinesiologic tests were conducted before and after each nap attempt. (3) Results197 naps were collected. Each nap at each time of day elicited an overall significant increase in tinnitus minimum masking level (MML). Each inter nap period elicited an overall significant decrease. Tinnitus modulations were found significantly correlated with nap sleep duration (Visual numeric scale on tinnitus loudness, VNS-L, p< 0.05), with snoring duration (MML, p< 0.001), with snoring average sound level (VNS on tinnitus intrusiveness, VNS-I, p< 0.05) and with sleep apnea count (VNS-I, p< 0.001). (4) ConclusionsThis study confirms objectively that tinnitus may increase following naps. No association was found between these modulations and somatosensory modulations involving the temporomandibular joint and cervical areas. However, it may be possible that nap-induced tinnitus modulations are a hidden form of somatosensory modulation as snoring and sleep apnea events are often related to tensor veli palatini muscle dysfunction.

Testing and Masking Policies and Hospital-Onset Respiratory Viral Infections

This cohort study examines the ratio between hospital- and community-onset respiratory viral infections at different levels of testing and masking from 2020 to 2024.

Simplified frequency selectivity measure as a potential candidate for hearing screening: changes with masker level and test-retest reliability of self-administered testing

Objectives This two-part pilot study investigated the feasibility of using a frequency selectivity measure (TFS) to develop a novel hearing screening test for cooperative adults. Study 1 determined the optimal masker level, while Study 2 assessed the reliability of a self-administered TFS test prototype performed at the selected masker level. Design and study sample Study 1 (normal hearing, n = 20) examined masker-level effects on TFS using a manual threshold determination method from an earlier study. Study 2 (normal hearing, n = 21; hearing loss, n = 5) evaluated the reliability of a self-administered TFS test using a new automated threshold determination procedure. Results Moderate masker levels (30–40 dB SPL) were suitable for the TFS measurements, with 40 dB SPL being optimal. Lower level (20 dB SPL) led to floor effects, while higher level (50 dB SPL) broadened cochlear tuning and reduced TFS values. The self-administered test demonstrated ±9 dB limit of agreement, with intra-subject absolute mean differences of 1.8–2.7 dB across test frequencies, indicating greater variability compared to the manual method. Conclusions The self-administered TFS test is a candidate for hearing screening, particularly for mild sensorineural hearing loss. However, further research is needed to reduce measurement variability and optimise testing for real-world use.

Effect of transcranial direct current stimulation on tinnitus modulation: A randomized, double-blind, and placebo-controlled clinical trial: Effect of tDCS on tinnitus modulation: A clinical trial

ObjectivesTo evaluate the short and long-term effects of anodal tDCS (a-tDCS) targeting the left temporoparietal area (LTA) on tinnitus severity, annoyance, and loudness. MethodsThis is a double-blind, randomized, sham-controlled, and parallel-group clinical trial. A total of 42 individuals with tinnitus were randomized to a-tDCS (n = 24) or sham tDCS (n = 18). The a-tDCS group received tDCS over the LTA during five consecutive day sessions (2 mA, 20 min). The sham group received a placebo current with the same characteristics as the a-tDCS group. Participants were assessed at baseline, after the fifth session, and at the 30-day follow-up, using hearing assessments and symptom questionnaires. ResultsThere was no effect of comparison between groups or interaction effect (time x group) in all hearing assessments and symptom questionnaires. There was only a main effect of time for Tinnitus Handicap Inventory - THI [F(1.642, 45.988) = 5.128; p = 0.014; η2 = 0.155]. Bonferroni post hoc showed that there was a significant difference in THI in the sham group between pre and post-treatment [CI (0.107, 14.643; p = 0.046)]. However, there was no difference between pre-treatment and follow-up THI, or between post-treatment and follow-up THI. There was no treatment effect on tinnitus severity (assessed by Tinnitus Functional Inventory - TFI), tinnitus annoyance or loudness (assessed by Visual Analogue Scale - VAS), or tinnitus pitch, loudness or minimum masking level (assessed by tinnitometry). ConclusionFive consecutive sessions of a-tDCS targeting LTA do not improve tinnitus severity, annoyance, and loudness. Future studies should investigate if other tDCS protocols are effective or a combination of tDCS with other forms of treatment.

Effect of Level and Frequency of Forward Masker on Auditory Brainstem Response.

Forward masking (FM) is characterized by the perception of a signal being reduced or wholly masked due to a preceding sound (masker) of the same or different frequencies that offers a challenge for the auditory system to resolve. Considering that the off-frequency masker is expected to undergo linear processing compared to the on-frequency masker at the signal place, it reflects the peripheral auditory systems' compressive response. Thus, the present study focused on employing FM electrophysiological analogous such as auditory brainstem responses (ABR) to the behavioral masking experiments to objectively measure the frequency and level of processing in the auditory system, from the periphery to the brainstem level. The study was an observational research on 21 female volunteers. ABR was obtained using a tone-on-tone FM paradigm for 1000- and 4000-Hz probe stimuli. An experiment used two forward maskers, on-frequency and off-frequency, with varying levels from 50 to 70 dB SPL. A progressive shift for Vth peak latency and reduction in response amplitude was observed in proportion to the increase of masker level for both the probe stimuli and the masking experiments. However, ABR responses in neither masking condition were observed to differ between 60 and 70 dB SPL. FM ABR experiments are an assessment tool for estimating frequency and level processing in the auditory system, providing good efficiency, reliability, and less subject bias compared to behavioral measures.

Age-Related Listening Performance Changes Across Adulthood.

This study compares auditory processing performance across different decades of adulthood, including young adults and middle-aged individuals with normal hearing and no spontaneous auditory complaints. We assessed 80 participants with normal hearing, at least 10 years of education, and normal global cognition. The participants completed various auditory tests, including speech-in-noise, dichotic digits, duration, pitch pattern sequence, gap in noise, and masking level difference. In addition, we conducted working memory assessments and administered a questionnaire on self-perceived hearing difficulties. Our findings revealed significant differences in auditory test performance across different age groups, except for the masking level difference. The youngest group outperformed all other age groups in the speech-in-noise test, while differences in dichotic listening and temporal resolution emerged from the age of 40 and in temporal ordering from the age of 50. Moreover, higher education levels and better working memory test scores were associated with better auditory performance as individuals aged. However, the influence of these factors varied across different auditory tests. It is interesting that we observed increased self-reported hearing difficulties with age, even in participants without spontaneous auditory complaints. Our study highlights significant variations in auditory test performance, with noticeable changes occurring from age 30 and becoming more pronounced from age 40 onward. As individuals grow older, they tend to perceive more hearing difficulties. Furthermore, the impact of age on auditory processing performance is influenced by factors such as education and working memory.

Experimental verification of the variability of amplitude modulation (AM) from wind turbines in relation to its assessment for annoyance

The analysis of the influence of amplitude modulation (AM) on the annoyance of noise generated by wind turbines (WT) is still the subject of numerous studies. However, there is still a lack of widely accepted quantitative methods that would determine the degree of influence of modulation phenomena on noise perception. The study analyzed the variability of the depth of AM over time within different frequency-ranges. The research was based on long-term measurements at selected measurement locations. Long-term measurement ensured consideration of diverse propagation conditions. The collected data were segmented into time intervals, which included basic AM parameters - depth, modulation frequency, and frequency band in which the AM was observed, as well as wind speed and direction. Statistical analysis of the gathered dataset was used to assess the regularity of distinguished AM parameters in correlation with WT noise energy values and recorded non-acoustic parameters. A significant variability of AM depth was observed depending on the frequency band, masking level, and position relative to the wind direction. By adopting a criterion for assessing the annoyance of WT noise (according to AMWG) with a threshold depth of AM not less than 2 dB, it was noticed in over 30% of the analyzed intervals.

Can Residual Inhibition Predict the Success of Sound Enrichment Treatment for Tinnitus?

The objective of this study was to investigate whether residual inhibition (RI), which provides information on the relationship between tinnitus and increased spontaneous activity in the auditory system, is a predictor for the success of sound enrichment treatment. Tinnitus patients were divided into two groups based on whether RI was achieved (RI+) or not (RI-). All participants underwent sound enrichment. Psychosomatic measures (for tinnitus severity, discomfort, attention deficit and sleep difficulties), Tinnitus Handicap Inventory (THI), minimum masking level (MML), and tinnitus loudness level (TLL) results were compared before and at 1, 3, and 6 months after treatment. Sixty-seven chronic tinnitus patients were divided into two groups based on whether RI was achieved (RI+) or not (RI-). There were 38 patients in the RI+ group and 29 in the RI- group. There was a statistically significant difference between the groups in psychosomatic measures, THI, MML and TLL scores at the post-treatment 6 months after treatment (p <.05). There was a statistically significant decrease in psychosomatic measures, THI, MML and TLL scores during the treatment period in the RI+ group, but not in the RI- group. RI may predict the prognosis of tinnitus treatments used in clinics to reduce the spontaneous firing rate of neurons in the central auditory system, and that RI positivity may be a predictor of treatment success in sound enrichment.

A study on impact of tinnitus masking on psychophysical and tinnitus tuning curve in participants with hearing impairment suffering from severe tinnitus

Background: Tinnitus can be treated by using different pedagogies of management approaches in which tinnitus masking has been acclaimed most evidence-based approach. Psychophysical tuning curve and tinnitus tuning curve explored as least interested procedures in tinnitus research. This noteworthy but nonspecific psychophysical domain may throw a light on need of the present research. Aim of the study was to find out the effect of tinnitus masking on Psychophysical tuning curve and tinnitus tuning curve. Method: A total of 30 native Bengali speaking participants were included in this study, having mean age of 45.9 years and SD was 6.46. All the participants had unilateral subjective tinnitus with Mild to Moderately severe sensorineural hearing loss. Quasi-experimental research design was used. Dual channel audiometer (MAICO MA 53) with supra-aural TDH 39 headphone was used for psychoacoustic measurements of tinnitus (including pitch matching, loudness matching, minimum masking level etc.) and to provide tinnitus masking therapy. MATLAB version 9.5 was used to develop noise to assess PTC and TTC using Sennheiser HD 201 headphone routed through MAICO MA 53 audiometer via stereo jack and cable. Tinnitus masking therapy was carried out for 30 sessions by using regimen of MML +20 dB of masking level for 30 minutes duration for each session with matched pitch. PTC and TTC were measured before and 30 sessions-after tinnitus masking therapy. PTC was measured using 1000 Hz pure tone at 10 dBSLl as reference followed by four narrow band noise with centre frequency of 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz pertaining to 312 Hz band width as developed by MATLAB software. TTC was measured using the same noise with reference to matched tinnitus pitch. All the above-mentioned conditions forced choice procedure was carried out in dBHL frame work. Results: Wilcoxon sign rank test was used at 95% confidence level to check the influence of tinnitus masking therapy on PTC and TTC measures. Significant changes were portrayed at 1000 Hz and 4000 Hz respectively in PTC measure and at 500 Hz, 1000 Hz, 2000 Hz and 4000 Hz respectively in TTC measures. Conclusion: This study preliminarily provides information regarding influence on tinnitus pitch domains which has been psychoacoustically systematically measured as PTC and TTC. These two psychoacoustic signatures may be treated as prognostic biomarker of tinnitus management in future using replicable research using different methodology or using statistical basis of data mining. At that point conclusive remarks may not throw a clear indication based on the results found in this study.

Monaural and binaural masking release with speech-like stimuli.

The relevance of comodulation and interaural phase difference for speech perception is still unclear. We used speech-like stimuli to link spectro-temporal properties of formants with masking release. The stimuli comprised a tone and three masker bands centered at formant frequencies F1, F2, and F3 derived from a consonant-vowel. The target was a diotic or dichotic frequency-modulated tone following F2 trajectories. Results showed a small comodulation masking release, while the binaural masking level difference was comparable to previous findings. The data suggest that factors other than comodulation may play a dominant role in grouping frequency components in speech.

Masking level differences under two different measurement conditions: A normative study of young adults.

The objective of this study was to determine the gender-specific normative values of masking level difference (MLD) in healthy young adults for two different measurement conditions. One hundred young adults between the ages of 19 and 25 were included. Tympanometry, pure tone audiometry, and MLD were performed. In the first MLD measurement condition, the threshold level where the signal was out of phase and the noise was in phase (SπNo) was subtracted from the threshold level where the signal and noise were in phase (SoNo). In the second MLD measurement condition, the threshold level where the signal was in phase and the noise was out of phase (SoNπ) was subtracted from the threshold level where the signal and noise were in phase (SoNo). The mean test scores were obtained in decibels. Comparisons were made in terms of gender and conditions. The mean MLD for SoNo-SπNo condition was 10.3±1.99dB. For SoNo-SoNπ condition, the mean MLD was 6.72±2.38dB. A significant difference was determined between the MLD under two different measurement conditions (p <.05). There was no significant difference in terms of gender (p >.05). Mean normative values of MLD test scores in gender-specific healthy young adults for two different measurement conditions are presented.

Binaural Interaction Component and Behavioral Auditory Processing in the Elderly with Hearing Loss: Preliminary Study

Purpose: The binaural interaction component (BIC) is presumed to reflect binaural hearing abilities, including spatial hearing. This study aims to record BIC amplitudes and examine their relationship with behavioral auditory tests.Methods: Nine elderly adults with hearing loss (eight males and one female) participated in this study. The BIC was derived from the wave V amplitude of the auditory brainstem response (ABR) and the N1-P2 amplitude of the auditory late latency response (ALR). Behavioral auditory processing tests, including sentence recognition scores, localization scores, and masking level difference, were obtained and analyzed with respect to electrophysiological BICs.Results: BICs were more reliably identified in ALR compared to ABR. The ALR BIC elicited by a 2,000 Hz tone burst showed a significant correlation with sentence recognition scores in both quiet and noise, as well as localization scores at 2,000 Hz. Other variables also demonstrated significant interrelationships.Conclusion: This study suggests that the ALR BIC elicited by a 2,000 Hz tone burst may be a key physiological component representing spatial hearing abilities in individuals with hearing loss. More robust conclusions can be drawn from future studies with larger sample sizes and more sophisticated designs.

Effect of stimulus duration on estimates of human cochlear tuning

Auditory masking methods originally employed to assess behavioral frequency selectivity have evolved over the years to infer cochlear tuning. Behavioral forward masking thresholds for spectrally notched noise maskers and a fixed, low-level probe tone provide accurate estimates of cochlear tuning. Here, we use this method to investigate the effect of stimulus duration on human cochlear tuning at 500 Hz and 4 kHz. Probes were 20-ms sinusoids at 10 dB sensation level. Maskers were noises with a spectral notch symmetrically and asymmetrically placed around the probe frequency. For seven participants with normal hearing, masker levels at masking threshold were measured in forward masking for various notch widths and for masker durations of 30 and 400 ms. Measurements were fitted assuming rounded exponential filter shapes and the power spectrum model of masking, and equivalent rectangular bandwidths (ERBs) were inferred from the fits. At 4 kHz, masker thresholds were higher for the shorter maskers but ERBs were not significantly different for the two masker durations (ERB30ms=294 Hz vs. ERB400ms=277 Hz). At 500 Hz, by contrast, notched-noise curves were shallower for the 30-ms than the 400-ms masker, and ERBs were significantly broader for the shorter masker (ERB30ms=126 Hz vs. ERB400ms=55 Hz). We discuss possible factors that may underlay the duration effect at low frequencies and argue that it may not be possible to fully control for those factors. We conclude that tuning estimates are not affected by maker duration at high frequencies but should be measured and interpreted with caution at low frequencies.

Central Auditory Processing Abilities in Children with Non-Syndromic Cleft Lip/and Palate-a Behavioural Study.

The present study aimed to assess the central auditory processing abilities and working memory in children with non-syndromic cleft lip and palate (NSCLP) and to compare with the developed normative and craniofacially normal peers. Sixteen NSCLP children aged 7 to 12 years and fifteen craniofacially normal peers were recruited in this study. Speech perception in noise Kannada (SPIN-K), gap detection threshold (GDT), dichotic consonant-vowel (DCV), and masking level difference (MLD) tests were administered to assess various central auditory processing abilities. Working memory abilities were assessed by using forward-digit span and backward-digit span tests. The results showed significant differences in SPIN-K, dichotic CV, GDT, forward digit, and backward digit span scores between children with NSCLP and craniofacially normal peers. Thus, it can be concluded from the present study that children with NSCLP have a risk of developing auditory processing deficits. To conclude, assessment of central auditory processing abilities in children with NSCLP is recommended.

Investigation of the effectiveness of sound enrichment in the treatment of tinnitus due to hearing loss.

In previous animal studies, sound enhancement reduced tinnitus perception in cases associated with hearing loss. The aim of this study was to investigate the efficacy of sound enrichment therapy in tinnitus treatment by developing a protocol that includes criteria for psychoacoustic characteristics of tinnitus to determine whether the etiology is related to hearing loss. A total of 96 patients with chronic tinnitus were included in the study. Fifty-two patients in the study group and 44 patients in the placebo group considered residual inhibition (RI) outcomes and tinnitus pitches. Both groups received sound enrichment treatment with different spectrum contents. The tinnitus handicap inventory (THI), visual analog scale (VAS), minimum masking level (MML), and tinnitus loudness level (TLL) results were compared before and at 1, 3, and 6 months after treatment. There was a statistically significant difference between the groups in THI, VAS, MML, and TLL scores from the first month to all months after treatment (p<.01). For the study group, there was a statistically significant decrease in THI, VAS, MML, and TLL scores in the first month (p<.01). This decrease continued at a statistically significant level in the third month of posttreatment for THI (p<.05) and at all months for VAS-1 (tinnitus severity) (p<.05) and VAS-2 (tinnitus discomfort) (p<.05). In clinical practice, after excluding other factors related to the tinnitus etiology, sound enrichment treatment can be effective in tinnitus cases where RI is positive and the tinnitus pitch is matched with a hearing loss between 45 and 55dB HL in a relatively short period of 1 month.

Dynamic Spatial Auditory Processing in the Elderly.

One of the most obvious functional effects of aging on the cognitive and processing processes of spatial hearing is the localization problem and the disorder of speech perception in noise. The purpose of the present study is to investigate the performance of dynamic spatial auditory processing in the elderly. This descriptive and analytical study was conducted on 60 young participants aged from18 to 25 years old and 60 elderly participants aged from 60 to 75 old years, using speech, spatial, and qualities of hearing scale (SSQ) questionnaire, binaural masking level difference (BMLD) and dynamic quick speech in noise (DS-QSIN) tests. Comparing the average scores of the tests and the questionnaire using the independent t test showed a significant difference between the two groups (p < 0.001). It was also found that gender had no effect on the results (p > 0.05). Aging is accompanied by different structural and functional changes in the auditory central nervous system, which leads to a decrease in speech perception in challenging listening environments, as well as a decrease in sound localization abilities, due to the reduction of temporal and spectral information. This problem affects the determination of the source of sound and the spatial cognition of the elderly and leads to a disturbance in the awareness of the auditory environment. Therefore, auditory rehabilitation programs can cause the improvement of spatial auditory processing performance and improve speech perception in noise in the elderly.

The effect of public health interventions on COVID-19 incidence in Queensland, Australia: a spatial cluster analysis

Background Using SaTScan™ Geographical Information Systems (GIS), spatial cluster analysis was used to examine spatial trends and identify high-risk clusters of Coronavirus 2019 (COVID-19) incidence in response to changing levels of public health intervention phases including international and state border closures, statewide vaccination coverage, and masking requirements. Methods Changes in COVID-19 incidence were mapped at the statistical area 2 (SA2) level using a GIS and spatial cluster analysis was performed using SaTScan™ to identify most-likely clusters (MLCs) during intervention phases. Results Over the study period, significant high-risk clusters were identified in Brisbane city (relative risk = 30.83), the southeast region (RR = 1.71) and moving to Far North Queensland (FNQ) (RR = 2.64). For masking levels, cluster locations were similar, with MLC in phase 1 in the southeast region (RR = 2.56) spreading to FNQ in phase 2 (RR = 2.22) and phase 3 (RR = 2.64). All p values <.0001. Conclusions Movement restrictions in the form of state and international border closures were highly effective in delaying the introduction of COVID-19 into Queensland, with very low levels of transmission prior to border reopening while mandatory masking may have played a role in decreasing transmission through behavioural changes. Early clusters were in highly populated regions, as restrictions eased clusters were identified in regions more likely to be rural or remote, with higher numbers of Indigenous people, lower vaccination coverage or lower socioeconomic status.

Measuring and modeling Gaussian noise disruption across frequency, level, and hearing status

Recent work suggested that older listeners with minimal hearing loss exhibit more forward masking for a highly fluctuating Gaussian noise (GN) masker relative to a low-fluctuation noise (LFN) masker. This threshold difference (GN–LFN) is referred to as GN disruption and was previously attributed to time-varying cochlear gain resulting from feedback control by the medial olivocochlear (MOC) system. However, thus far, masker conditions have been limited to 80 dB SPL at 4 kHz. The current study aims to challenge the hypothesis that the physiological basis of GN disruption is the MOC system using behavioral measures and computational models across multiple target and masker frequencies (0.5, 1, 2, and 4 kHz), masker levels (80-, 65-, and 50-dB SPL), masker-signal delays (25- and 75-ms), participant age ranges (18–30 and 60–75), and hearing statuses (normal hearing, sensorineural hearing loss). Additionally, speech recognition using IEEE sentences will be measured with GN and LFN maskers. Although testing will not be completed until 2025, preliminary data from 20 younger participants with normal hearing suggest that GN disruption is greater for higher than lower masker and probe frequencies, that GN disruption is similar across masker levels, and that refinements to the computational model are needed to more accurately predict GN disruption.

A spatial digit task for assessing binaural function in individuals with hearing loss

Spatial hearing is crucial in occupational tasks, yet until 2019, US Army fitness-for-duty requirements only considered hearing thresholds in the better ear. The regulation change introduced the Military Operational Hearing Test (MOHT) for those with worse-ear thresholds exceeding 40 dB HL at 0.5 or 1 kHz, or 60 dB HL at 2 kHz. This led to the development of the Spatial Digit Test (SDT) to assess binaural function in individuals with poor hearing in one ear but sufficiently good hearing in the other ear to pass a speech-in-noise test. The SDT involves digit pairs presented with Interaural Time Delays (ITDs) of +/−800 μs. Two studies were conducted: a validation study with over 200 individuals, and a verification study with more than 130 undergoing MOHT exams. Results show that individuals with normal auditory thresholds perform very well on the SDT, with about 95% correctly identifying at least 8 digits and 75% correctly identifying all 10. In contrast, only about 50% of individuals with monaural losses who took the SDT as part of the MOHT identified 8 or more digits. Results of the SDT were correlated both with subjective hearing complaints and with the Binaural Masking Level Difference. In conclusion, the SDT proves valuable for identifying individuals struggling using ITD cues to segregate and localize simultaneously presented speech signals.

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.