Awareness, attitudes and perceptions of students towards leisure noise in Durban, South Africa.

BACKGROUND:  Young adults are exposed to high noise levels in leisure venues, which increases their risk of hearing loss, and can affect their quality of life. OBJECTIVES:  The aim of this study was to describe the young adults' awareness, attitudes and perceptions towards leisure noise at a university in South Africa. METHOD:  A descriptive cross-sectional study design with quantitative methods of data was considered for this study. Students from first to fourth years in the Education Department of a local university in Durban, South Africa, who were aged 18 years old - 25 years old were invited to participate in an online survey. RESULTS:  Of the 462 participants, most had a general awareness on noise and hearing loss but lacked knowledge on the negative effect of loud noise, with 95.2% using personal listening devices, followed by visiting restaurants and gyms, and 48.3% being unsure if noise can damage hearing permanently. They were unaware of methods to reduce their exposure to noise. A significant relationship between awareness of noise and attitudes (p = 0.029) indicated that the higher the level of awareness regarding leisure noise, the better their attitude and behaviour, thus the lower the risk of hearing loss. CONCLUSION:  The results highlight the need for implementing the World Health Organization (WHO) noise regulations and providing education for this age group to prevent irreversible hearing loss through exposure to leisure noise.Contribution: A national study is recommended to increase research evidence.

Music level preference and perceived exercise intensity in group spin classes.

CONTEXT: Sound levels in fitness classes often exceed safe levels despite studies that show many participants find high sound levels stressful. AIMS: The objective is to determine if lower sound levels in spinning classes significantly impact exercise intensity and to determine if class participants prefer the music played at lower levels. SETTINGS AND DESIGN: Observational study of 1-hour group spin classes. METHODS AND MATERIALS: Sound levels were measured in 18 spin classes over two weeks. No adjustments were made in week-1 and sound levels were decreased by 3 dB in week-2. Participant preferences and data on post-class hearing changes were collected via post-class questionnaires (n = 213) and divided into three terciles based on the total sound exposure of corresponding classes. STATISTICAL ANALYSIS USED: Unweighted survey generalized linear models are used to sort the causal relationships between different variables simultaneously and participant responses. The Chi-square test is used to reveal statistically significant relationships between two or more categorical variables. RESULTS: When mean sound levels exceeded 98.4 dBC, respondents were 23 times more likely to report the music as too loud than too quiet (P < 0.05), and four times more likely to prefer a decrease, rather than an increase, in sound level (P < 0.05). There was no significant difference in respondents reporting high exercise intensity between the middle (95.7-98.1 dBC) and upper (98.4-101.0 dBC) terciles, 67.1% and 71.8%, respectively (P = 0.53). Overall, 25.9% of respondents reported auditory symptoms following classes. Analysis in the context of dBA and dBC produced congruent conclusions and interpretations. CONCLUSIONS: Sound levels in many fitness classes remain dangerously high. However, music level can be lowered without a significant impact on perceived exercise intensity and many participants prefer lower sound levels than current levels.

Associations between speech recognition at high levels, the middle ear muscle reflex and noise exposure in individuals with normal audiograms.

It has been hypothesized that noise-induced cochlear synaptopathy in humans may result in functional deficits such as a weakened middle ear muscle reflex (MEMR) and degraded speech perception in complex environments. Although relationships between noise-induced synaptic loss and the MEMR have been demonstrated in animals, effects of noise exposure on the MEMR have not been observed in humans. The hypothesized relationship between noise exposure and speech perception has also been difficult to demonstrate conclusively. Given that the MEMR is engaged at high sound levels, relationships between speech recognition in complex listening environments and noise exposure might be more evident at high speech presentation levels. In this exploratory study with 41 audiometrically normal listeners, a combination of behavioral and physiologic measures thought to be sensitive to synaptopathy were used to determine potential links with speech recognition at high presentation levels. We found decreasing speech recognition as a function of presentation level (from 74 to 104 dBA), which was associated with reduced MEMR magnitude. We also found that reduced MEMR magnitude was associated with higher estimated lifetime noise exposure. Together, these results suggest that the MEMR may be sensitive to noise-induced synaptopathy in humans, and this may underlie functional speech recognition deficits at high sound levels.

How low must you go? Effects of low-level noise on cochlear neural response.

Prolonged exposure to low-level noise has often been used scientifically as well as clinically to induce neuroplastic changes within the central auditory pathway in order to reduce central gain, suppress tinnitus and hyperacusis, and modulate different features of central auditory processing. A fundamental assumption underling these studies is that the noise exposure levels are so low that they have no effect on the neural output of the cochlea. Therefore, functional changes occurring in the central auditory pathway must be the results of central rather than peripheral changes. In an attempt to identify long-term noise exposures that did not cause peripheral changes, we measured the compound action potential (CAP) input/output functions from control rats and rats exposed for 6-weeks to 18-24 kHz noise presented at 25, 45, 55, 65, 75 or 85 dB SPL. Exposures >65 dB SPL significantly increased CAP thresholds; the critical intensity (Ct) below which no threshold shift occurred was estimated to be 55 dB SPL. Exposures >55 dB SPL significantly reduced suprathreshold CAP amplitudes; the critical intensity (Ca) below which no amplitude change was predicted to occur was a remarkably low level of 19 dB SPL. These results demonstrate that even extremely low-intensity long duration exposures can disrupt the neural output of the cochlea; these peripheral modifications are likely to contribute to the extensive compensatory changes observed at multiple levels of the central auditory pathway, neural network changes aimed at re-establishing homeostasis.

Does occupational noise matter amongst manufacturing (small and medium enterprises) workers? Empirical evidence from Magaba, Mbare, Zimbabwe.

BACKGROUND: The significance of how occupational noise can influence attitudes towards occupational noise exposure, susceptibility to hearing loss and job performance has generally been neglected in the past studies. OBJECTIVES: The aim of this study was to determine the impact of occupational noise on attitudes towards occupational noise exposure, susceptibility to hearing loss and job performance of manufacturing small and medium enterprises (SMEs) workers in Zimbabwe. METHOD: A survey was conducted involving 250 respondents, including manufacturing SME workers, and the hypotheses were analysed by applying structural equation modelling. RESULTS: Occupational noise had a positive and significant effect on attitudes towards occupational noise exposure and perceived susceptibility to hearing loss amongst manufacturing SME workers. In addition, attitudes towards exposure to occupational noise and the perceived susceptibility of hearing loss have had a positive and significant impact on manufacturing SME workers' job performance. CONCLUSION: The novelty of the research is its analysis of occupational noise as an indicator of attitudes towards occupational noise exposure and susceptibility to hearing loss as well as job performance. This study provides practitioners with beneficial implications. Collective knowledge on occupational noise could help manufacturing SME managers in recognising the perceptions of employees on occupational noise and how it ultimately affects job performance. Moreover, this study is intended to add new knowledge to the current body of African occupational noise literature - a context that has not received much research attention in developing countries.

Effects of Cardiovascular Health Factors and Personal Listening Behaviors on Hearing Sensitivity in College-Aged students.

OBJECTIVES: This study examined the association between pure tone hearing sensitivity and music listening behaviors among traditional college-aged students and sought to determine factors that mediate hearing sensitivity, including health and fitness levels, gender, and personal listening device (PLD) use. METHODS: A convenience sample of college students (N = 182; 133 females, 49 males, mean age = 19.8 ± 1.4 year, average PLD use = 1.52 ± 7.1 hours•day-1) completed hearing assessments, music listening behavior questionnaires, and health and fitness tests. RESULTS: Most students listened to music at safe intensity levels (<80 dBA), though 18% had higher hearing levels (≥25 dB HL at one of the measured frequencies). Longer listening duration behavior approached but did not reach a statistical association with compromised hearing sensitivity. Of all variables measured, including cardiovascular health, fitness, and music listening, two variables: total cholesterol: triglycerides (TC:TG) and total cholesterol: high-density lipoproteins (TC:HDL) significantly associated with hearing sensitivity at 2 kHz. The odds hearing loss occurring at 4 kHz was 59% lower in females compared with males. CONCLUSION: The majority of college students had healthy music listening behavior and fitness, contributing to normal hearing sensitivity in most. In cases where greater hearing threshold levels at one or more frequencies was detected, TC:HDL and TC:TG were statistically related and at 2 kHz, males were more likely to demonstrate higher listening levels compared with females of similar health and fitness level.

Tinnitus and Self-Perceived Hearing Handicap in Firefighters: A Cross-Sectional Study.

Firefighters are susceptible to auditory dysfunction due to long-term exposure to noise from sirens, air horns, equipment, and tools used in forcible entry, ventilation, and extrication. In addition, they are exposed to ototoxic chemicals, particularly, during overhaul operations. Studies indicate that 40% of firefighters have hearing loss in the noise-sensitive frequencies of 4 and 6 kHz. Noise-induced hearing loss (NIHL) is often accompanied by tinnitus, which is characterized by ringing noise in the ears. The presence of phantom sounds can adversely affect the performance of firefighters. However, there has been limited research conducted on the prevalence of tinnitus in firefighters. We enrolled firefighters from Michigan, with at least 5 years of continuous service. The hearing handicap inventory for adults (HHIA) was used to determine the difficulty in hearing perceived by the firefighters and the tinnitus functional index (TFI) was used to determine the severity of tinnitus. Self-perceived hearing handicap was reported by 36% of the participants, while tinnitus was reported by 48% of the participants. The TFI survey indicated that 31% perceived tinnitus as a problem. More importantly, self-perceived hearing handicap was significantly associated with the incidence of tinnitus in firefighters, suggesting a potential link between occupational exposure to ototraumatic agents and tinnitus in firefighters.

The Role of Cognition in Common Measures of Peripheral Synaptopathy and Hidden Hearing Loss.

Purpose The aim of this study was to quantify the portion of variance in several measures suggested to be indicative of peripheral noise-induced cochlear synaptopathy and hidden hearing disorder that can be attributed to individual cognitive capacity. Method Regression and relative importance analysis was used to model several behavioral and physiological measures of hearing in 32 adults ranging in age from 20 to 74 years. Predictors for the model were hearing sensitivity and performance on a number of cognitive tasks. Results There was a significant influence of cognitive capacity on several measures of cochlear synaptopathy and hidden hearing disorder. These measures include frequency modulation detection threshold, time-compressed word recognition in quiet and reverberation, and the strength of the frequency-following response of the speech-evoked auditory brainstem response. Conclusions Measures of hearing that involve temporal processing are significantly influenced by cognitive abilities, specifically, short-term and working memory capacity, executive function, and attention. Research using measures of temporal processing to diagnose peripheral disorders, such as noise-induced synaptopathy, need to consider cognitive influence even in a young, healthy population.

Noise exposures and perceptions of hearing conservation programs among wildland firefighters.

Wildland firefighters are exposed to numerous noise sources that may be hazardous to their hearing. This study examined the noise exposure profiles for 264 wildland firefighters across 15 job categories. All 264 firefighters completed questionnaires to assess their use of hearing protection devices, enrollment in hearing conservation programs, and their overall perception of their noise exposure. Roughly 54% of firefighters' noise exposures exceeded the National Institute for Occupational Safety and Health recommended exposure limit of 85 decibels, A-weighted, over 8 hr, and 32% exceeded the Occupational Safety and Health Administration permissible exposure limit of 90 decibels, A-weighted, over 8 hr. Questionnaire results indicated good agreement between noise exposures and firefighters' perceptions of the noise hazard. Approximately 65% reported that they used some form of hearing protection; however, only 19% reported receiving any proper training regarding the use of hearing protection devices, with the majority of those firefighters relying on earplugs, including electronic and level-dependent earplugs, over earmuffs or other forms of hearing protectors. The results also suggest that improved communication and situational awareness play a greater role in the consistent use of hearing protection devices than other factors such as risk of developing noise-induced hearing loss. The study highlighted the challenges facing wildland firefighters and their management and the need for a comprehensive wildland fire agencies' hearing conservation program especially for firefighters who were exempt based on their occupational designations.

Behavioral evaluation of auditory function abnormalities in adult rats with normal hearing thresholds that were exposed to noise during early development.

Noise-exposed rat pups provide a model of early deprivation of sensory input to the central auditory system, allowing the study of developmental neuroplasticity. Our previous results have demonstrated that a brief exposure of rats to broadband noise (125 dB SPL 8 min, 14th postnatal day) at the onset of hearing resulted in an altered intensity perception and frequency discrimination in adulthood despite normal hearing thresholds. In this study, we assessed the gap-detection ability and possible presence of tinnitus- and hyperacusis-like behavior in adult rats after the same neonatal acoustic trauma, using measurements of the acoustic startle response (ASR) in quiet and noisy environments and its prepulse inhibition by gaps in noise (gap-PPI). A significant deficit in the ability to detect gap was observed in the exposed rats when 55 dB SPL broadband noise was used as background. An increase of noise intensity to 65-75 dB SPL led to strengthening of the gap-PPI in exposed animals, which approached the gap-PPI values of control animals at these levels. Behavioral signs of tinnitus (gap detection deficits in 10 kHz narrow band noise) were found in 25% of exposed rats. An increased sensitivity to continuous noise was manifested in all exposed rats by suppression of the ASR at significantly lower background noise levels than in the controls. This effect was particularly pronounced in rats with tinnitus-like behavior. Our results indicate that neonatal acoustic trauma, producing only a transient threshold shift, may produce permanent abnormalities in suprathreshold auditory functions and the development of tinnitus and hyperacusis-like behavior.

Evaluation of dichotic listening performance in normal-hearing, noise-exposed young females.

Recent animal studies have shown that intense noise exposures that produce robust temporary threshold shift (TTS) can inflict irreversible damage to the synaptic connections between the inner hair cells and auditory neurons. It was hypothesized that noise-induced cochlear synaptopathy may cause impaired acoustic encoding in the central auditory nervous system leading to impaired speech perception, particularly in challenging listening situations. The aim of the study was to evaluate the influence of high noise exposure background (NEB) on dichotic listening performance, speech-in-noise performance, and auditory brainstem responses (ABR) measured in young females with normal audiograms. The central hypothesis was that individuals with high NEB would exhibit reduced ABR wave I amplitude and subsequently would exhibit poorer performance on speech-in-noise and dichotic listening. In a sample of 32 females (14 with high NEB and 18 with low NEB) aged 18-35 years, the study compared behavioral hearing thresholds (from 250 to 16000 Hz), distortion-product otoacoustic emissions (DPOAEs, 1000-16000 Hz), click-evoked ABR, QuickSIN signal-to-noise ratio (SNR) loss and dichotic digit test (DDT). The results showed no clear association between NEB, and hearing thresholds, DPOAEs, click-evoked ABR measures, and QuickSIN SNR loss. Individuals with high NEB revealed significantly lower DDT scores and evidence of reduced right ear advantage compared to individuals with low NEB. The poorer performance in DDT and the ear asymmetry in DDT scores with normal ABR findings suggest that high NEB might alter the hemispheric organization of speech-sound processing and cognitive control. The clinical significance of the present findings is discussed.

Auditory system dysfunction in Brazilian gasoline station workers.

Objective: To examine the auditory system of Brazilian gasoline station workers using an extensive audiological test battery. Design: This was a cross-sectional study. The audiological evaluation included a questionnaire, pure-tone audiometry, acoustic immittance tests, transient-evoked otoacoustic emissions (TEOAEs), distortion product otoacoustic emissions (DPOAEs), auditory brainstem response (ABR) and P300 auditory-evoked potentials. Study sample: A total of 77 Brazilian gasoline station workers were evaluated, and their results were compared with those of 36 participants who were not exposed to chemicals or noise at work. The gasoline station employees worked in 18 different gas stations, and the noise area measurements from all gas stations revealed time-weighted averages below 85 dBA. Results: Of the 77 gasoline station workers evaluated, 67.5% had audiometric results within the normal range, but 59.7% reported difficulties in communication in noisy places. Gasoline station workers showed significantly poorer results than non-exposed control participants in one or more conditions of each of the audiological tests used, except P300. Conclusions: The results suggest that the gasoline station workers have both peripheral and central auditory dysfunctions that could be partly explained by their exposure to gasoline.

Knowledge, attitude, and practice of printing press workers towards noise-induced hearing loss.

CONTEXT: Noise-induced hearing loss (NIHL) is considered as a common occupational hazard among the industrial workers. The printing press is one of the common industrial set up where noise levels are often high. The awareness of people working in such a setup is generally less towards the hazards that is caused by noise exposure. AIM: The current study was designed to identify the knowledge, attitude, and practice (KAP) of printing press workers towards NIHL. SETTINGS AND DESIGN: : Cross-sectional study was carried using an adapted and validated KAP questionnaire. It was administered on 57 workers in Thiruvananthapuram, Kerala. METHODS AND MATERIAL: The study was carried out in two phases: phase I included the adaptation and validation of KAP questionnaire to printing press workers. Phase II comprised of the administration of the questionnaire among the study population. STATISTICAL ANALYSIS USED: : Descriptive statistics was used to compile the results. To measure the internal consistency Cronbach's alpha scale was used. RESULTS: The responses obtained from workers showed inadequate knowledge, negative attitudes in certain subdomains and poor practice. CONCLUSIONS: The findings from the present study sheds light on the dearth of awareness in printing press workers on hearing conservation and need of training programs to educate the printing press workers towards the effects of NIHL.

Analysis on Risk Factors of Depressive Symptoms in Occupational Noise-induced Hearing Loss Patients: A Cross-sectional Study.

OBJECTIVE: The aim of this study was to evaluate the risk factors of depressive symptoms in occupational noise-induced hearing loss (NIHL) patients. METHODS: A total of 106 patients were divided into depressive symptoms (ONHLPD) and without depressive symptoms (non-ONHLPD) according to the Self-rating Depression Scale. Questionnaires and laboratory data were collected and analyzed. Data were analyzed with independent t-test, Wilcoxon test, Pearson correlation analysis and multiple linear regression models. RESULTS: The prevalence of depressive symptoms was 53.8% in occupational NIHL patients. In ONHLPD, duration of the hearing loss, level of serum cortisol, scores of Pittsburgh Sleep Quality Index and Tinnitus Handicap Inventory were all significantly higher than those of non-ONHLPD. CONCLUSION: The prevalence of depressive symptoms was relatively high in occupational NIHL patients. Duration of the hearing loss, sleep quality and tinnitus severity were the risk factors for occupational NHIL patients with depressive symptoms.

Hearing loss in the trenches - a hidden morbidity of World War I.

BACKGROUND: One hundred years ago, millions of British and Allied troops were fighting in the trenches of the Great War. With a tenth of soldiers losing their lives, hearing loss seemed a low priority; however, vast numbers of troops sustained significant hearing loss. METHOD: A review was conducted of literature published between 1914 and 1925. RESULTS: Soldiers were exposed to up to 185 dB of sustained noise from new, high-energy weapons, which caused 'labyrinthine concussion'. Traumatic injuries, non-organic hearing loss and malingering were also common. One source estimated that 2.4 per cent of the army was disabled by hearing loss. However, many British doctors viewed this 'soldier's deafness' as a temporary affliction, resulting in soldiers being labelled as malingerers or 'hysterical'. CONCLUSION: Today, one can recognise that a scant evidence base and misconceptions influenced the mismanagement of hearing loss by otolaryngologists in World War I. However, noise-induced hearing loss is still very much a feature of armed conflict.

Longitudinal analysis of leisure noise exposure among adolescents with special focus on portable listening devices: the OHRKAN cohort study.

The aim was to investigate leisure noise exposure and sociodemographic determinants of risky leisure noise exposure over five years in 2148 students visiting grade 9 of any school type in a German city from 2009-2011. Within the OHRKAN cohort study, leisure noise exposure was calculated from literature-retrieved sound pressure levels (SPLs) and self-reported duration of 18 leisure activities at baseline and two follow-ups. Risky exposure was defined as exceeding 85 dB(A) averaged over a 40-h-week. Determinants of risky total leisure noise (TLN) exposure and risky exposure to portable listening devices (PLDs) were investigated using generalised estimating equations (GEEs). Up to 73% of students exceeded noise levels of 85 dB(A) at some timepoint. The noise exposure and importance of different leisure activities changed with increasing age. Risky exposure to TLN and PLDs was associated with lower education, single parent households and being male. Risky PLD exposure was additionally associated with a migrant background. Current prevention measures for leisure noise exposure must be extended to at-risk groups. Besides enhancing campaigns in lower education schools, acoustical insulation in sports halls, noise warnings on tools or in videogames could address especially men. Migrants need education about healthy PLD use in their native language if necessary.

Management of occupational noise induced hearing loss in the mining sector in South Africa: Where are the audiologists?

OBJECTIVE: This study was conducted to explore the scope of practice for occupational audiologists in the mining industry and the audiologists' involvement in hearing conservation programmes in South African mines. Additionally, this study investigated the mining industry's role in the audiologists' involvement, and assessed the audiologists' levels of preparedness for working in occupational audiology. METHODS: In-depth, qualitative telephone and face-to face interviews were conducted with seven occupational audiologists involved in the management of occupational, noise-induced hearing loss (ONIHL) in the South African mining sector. Snowball sampling was utilized to recruit possible participants for this study. Data were analysed using inductive thematic analysis. RESULTS: The following themes were identified: scope-context misalignment, juniorization of the experts, audiologists are important... but for what?, and limited training in occupational audiology. CONCLUSIONS: Our evidence highlights important gaps in HCPs in South Africa. The fact that the audiologists responsible for the management of ONIHL are only minimally and peripherally involved may play a significant role in the lack of progress reported in the management of ONIHL in the South African mining sector.

Effects of lifetime noise exposure on the middle-age human auditory brainstem response, tinnitus and speech-in-noise intelligibility.

Recent animal studies have shown that the synapses between inner hair cells and the dendrites of the spiral ganglion cells they innervate are the elements in the cochlea most vulnerable to excessive noise exposure. Particularly in rodents, several studies have concluded that exposure to high level octave-band noise for 2 h leads to an irreversible loss of around 50% of synaptic ribbons, leaving audiometric hearing thresholds unaltered. Cochlear synaptopathy following noise exposure is hypothesized to degrade the neural encoding of sounds at the subcortical level, which would help explain certain listening-in-noise difficulties reported by some subjects with otherwise 'normal' hearing. In response to this peripheral damage, increased gain of central stages of the auditory system has been observed across several species of mammals, particularly in association with tinnitus. The auditory brainstem response (ABR) wave I amplitude and waves I-V amplitude ratio have been suggested as non-invasive indicators of cochlear synaptopathy and central gain activation respectively, but the evidence for these hearing disorders in humans is inconclusive. In this study, we evaluated the influence of lifetime noise exposure (LNE) on the human ABR and on speech-in-noise intelligibility performance in a large cohort of adults aged 29 to 55. Despite large inter-subject variability, results showed a moderate, but statistically significant, negative correlation between the ABR wave I amplitude and LNE, consistent with cochlear synaptopathy. The results also showed (a) that central gain mechanisms observed in animal studies might also occur in humans, in which higher stages of the auditory pathway appear to compensate for reduced input from the cochlea; (b) that tinnitus was associated with activation of central gain mechanisms; (c) that relevant cognitive and subcortical factors influence speech-in-noise intelligibility, in particular, longer ABR waves I-V interpeak latencies were associated with poorer performance in understanding speech in noise when central gain mechanisms were active; and (d) absence of a significant relationship between LNE and tinnitus, central gain activation or speech-in-noise performance. Although this study supports the possible existence of cochlear synaptopathy in humans, the great degree of variability, the lack of uniformity in central gain activation and the significant involvement of attention in speech-in-noise performance suggests that noise-induced cochlear synaptopathy is, at most, one of several factors that play a role in humans' speech-in-noise performance.

Impaired speech perception in noise with a normal audiogram: No evidence for cochlear synaptopathy and no relation to lifetime noise exposure.

In rodents, noise exposure can destroy synapses between inner hair cells and auditory nerve fibers ("cochlear synaptopathy") without causing hair cell loss. Noise-induced cochlear synaptopathy usually leaves cochlear thresholds unaltered, but is associated with long-term reductions in auditory brainstem response (ABR) amplitudes at medium-to-high sound levels. This pathophysiology has been suggested to degrade speech perception in noise (SPiN), perhaps explaining why SPiN ability varies so widely among audiometrically normal humans. The present study is the first to test for evidence of cochlear synaptopathy in humans with significant SPiN impairment. Individuals were recruited on the basis of self-reported SPiN difficulties and normal pure tone audiometric thresholds. Performance on a listening task identified a subset with "verified" SPiN impairment. This group was matched with controls on the basis of age, sex, and audiometric thresholds up to 14 kHz. ABRs and envelope-following responses (EFRs) were recorded at high stimulus levels, yielding both raw amplitude measures and within-subject difference measures. Past exposure to high sound levels was assessed by detailed structured interview. Impaired SPiN was not associated with greater lifetime noise exposure, nor with any electrophysiological measure. It is conceivable that retrospective self-report cannot reliably capture noise exposure, and that ABRs and EFRs offer limited sensitivity to synaptopathy in humans. Nevertheless, the results do not support the notion that noise-induced synaptopathy is a significant etiology of SPiN impairment with normal audiometric thresholds. It may be that synaptopathy alone does not have significant perceptual consequences, or is not widespread in humans with normal audiograms.