Noise Induced Hearing Loss and Tinnitus-New Research Developments and Remaining Gaps in Disease Assessment, Treatment, and Prevention

Advancing noise management in aviation: Strategic approaches for preventing noise-induced hearing loss

As urbanization and population growth escalate, the challenge of noise pollution intensifies, particularly within the aviation industry. This review examines current insights into noise-induced hearing loss (NIHL) in aviation, highlighting the risks to pilots, cabin crew, aircraft maintenance engineers, and ground staff from continuous exposure to high-level noise. It evaluates existing noise management and hearing conservation strategies, identifying key obstacles and exploring new technological solutions. While progress in developing protective devices and noise control technologies is evident, gaps in their widespread implementation persist. The study underscores the need for an integrated strategy combining regulatory compliance, technological advances, and targeted educational efforts. It advocates for global collaboration and policy development to safeguard the auditory health of aviation workers and proposes a strategic framework to enhance hearing conservation practices within the unique challenges of the aviation sector.

Comprehensive Characterization of Hearing Loss and Tinnitus in Military-Affiliated and Non-Military-Affiliated Individuals

PURPOSE

Military-affiliated individuals (MIs) are at a higher risk of developing hearing loss and tinnitus. While these disorders are well-studied in MIs, their impact relative to non-military-affiliated individuals (non-MIs) remains understudied. Our study compared hearing, speech-in-noise (SIN) perception, and tinnitus characteristics between MIs and non-MIs.

METHOD

MIs (n = 84) and non-MIs (n = 193) underwent hearing threshold assessment and Quick Speech-in-Noise Test. Participants with tinnitus completed psychoacoustic tinnitus matching, numeric rating scale (NRS) for loudness and annoyance, and Tinnitus Functional Index. Comorbid conditions such as anxiety, depression, and hyperacusis were assessed. We used a linear mixed-effects model to compare hearing thresholds and SIN scores between MIs and non-MIs. A multivariate analysis of variance compared tinnitus characteristics between MIs and non-MIs, and a stepwise regression was performed to identify predictors of tinnitus severity.

RESULTS

MIs exhibited better hearing sensitivity than non-MIs; however, their SIN scores were similar. MIs matched their tinnitus loudness to a lower intensity than non-MIs, but their loudness ratings (NRS) were comparable. MIs reported greater tinnitus annoyance and severity on the relaxation subscale, indicating increased difficulty engaging in restful activities. Tinnitus severity was influenced by hyperacusis and depression in both MIs and non-MIs; however, hearing loss uniquely contributed to severity in MIs.

CONCLUSIONS

Our findings suggest that while MIs may exhibit better or comparable listening abilities, they were significantly more affected by tinnitus than non-MIs. Furthermore, our study highlights the importance of assessing tinnitus-related distress across multiple dimensions, facilitating customization of management strategies for both MIs and non-MIs.

Impacts of noise-induced hearing loss on sleep, health, and workplace: Multi-group analysis

Noise-induced hearing loss (NIHL) is a significant occupational health concern, particularly in industries with high levels of noise exposure. This study examines the effects of NIHL on sleep quality, daily life health conditions, and workplace health problems among workers. A total of 1285 workers participated in the study, and the data were analyzed using partial least squares structural equation modeling (PLS-SEM) to assess the impacts of NIHL. The analysis included a multi-group analysis to differentiate the effects between workers who wear noise protection and those who do not. Our findings indicate that NIHL significantly affects sleep quality, with a coefficient of 0.263 (t = 9.957, p<0.001), daily life health conditions with a coefficient of 0.296 (t = 10.793, p<0.001), and workplace health problems with a coefficient of 0.345 (t = 13.814, p<0.001). The multi-group analysis revealed more severe impacts on sleep and health in the non-wearing group compared to the noise-protection-wearing group, with statistically significant differences in path coefficients for sleep disorders (-0.033), health problems in daily life (-0.184), and health problems in the workplace (-0.190), all showing p-values of 0.000. These results underscore the detrimental effects of NIHL on multiple aspects of workers' health and emphasize the importance of wearing noise protection to mitigate these effects. This study provides vital insights for both researchers and practitioners in public health, suggesting that improved noise protection strategies are essential for protecting workers in noisy environments.

Neural Mechanisms of Nonauditory Effects of Noise Exposure on Special Populations

Due to the abnormal structure and function of brain neural networks in special populations, such as children, elderly individuals, and individuals with mental disorders, noise exposure is more likely to have negative psychological and cognitive nonauditory effects on these individuals. There are unique and complex neural mechanisms underlying this phenomenon. For individuals with mental disorders, there are anomalies such as structural atrophy and decreased functional activation in brain regions involved in emotion and cognitive processing, such as the prefrontal cortex (PFC). Noise exposure can worsen these abnormalities in relevant brain regions, further damaging neural plasticity and disrupting normal connections and the transmission of information between the PFC and other brain areas by causing neurotransmitter imbalances. In the case of children, in a noisy environment, brain regions such as the left inferior frontal gyrus and PFC, which are involved in growth and development, are more susceptible to structural and functional changes, leading to neurodegenerative alterations. Furthermore, noise exposure can interrupt auditory processing neural pathways or impair inhibitory functions, thus hindering children's ability to map sound to meaning in neural processes. For elderly people, age-related shrinkage of brain regions such as the PFC, as well as deficiencies in hormone, neurotransmitter, and nutrient levels, weakens their ability to cope with noise. Currently, it is feasible to propose and apply coping strategies to improve the nonauditory effects of noise exposure on special populations based on the plasticity of the human brain.

Tinnitus: A Dimensionally Segregated, yet Perceptually Integrated Heterogeneous Disorder

OBJECTIVES

Tinnitus subtypes are proposed to lie on a continuum of different symptom dimensions rather than be categorical. However, there is no comprehensive empirical data showing this complex relationship between different tinnitus symptoms. The objective of this study is to provide empirical evidence for the dimensional nature of tinnitus and how different auditory and non-auditory symptoms interact with each other through complex interactions. We do this using graph theory, a mathematical tool that empirically maps this complex interaction. This way, graph theory can be utilised to highlight a new and possibly important outlook on how we can understand the heterogeneous nature of tinnitus.

DESIGN

In the current study, we use the screening databases of the Treatment Evaluation of Neuromodulation for Tinnitus-Stage A1 (TENT-A1) and A2 (TENT-A2) randomised trials to delineate the dimensional relationship between different clinical measures of tinnitus as a secondary data analysis. We first calculate the empirical relationship by computing the partial correlation. Following this, we use different measures of centrality to describe the contribution of different clinical measures to the overall network. We also calculate the stability of the network and compare the similarity and differences between TENT-A1 and TENT-A2.

RESULTS

Components of the auditory subnetwork (loudness discomfort level, sound sensitivity, average hearing loss and high frequency hearing loss) are highly inter-connected in both networks with sound sensitivity and loudness discomfort level being highly influential with high measures of centrality. Furthermore, the relationship between the densely connected auditory subnetwork with tinnitus-related distress seems to vary at different levels of distress, hearing loss, duration and age of the participants.

CONCLUSION

Our findings provide first-time evidence for tinnitus varying in a dimensional fashion illustrating the heterogeneity of this phantom percept and its ability to be perceptually integrated, yet behaviourally segregated on different symptomatic dimensions.

A Comprehensive Review of Auditory and Non-Auditory Effects of Noise on Human Health

OBJECTIVE

Excessive noise is unpleasant and induces several physiological and psychological effects. Noise pollution is a potential threat to humans, particularly those continuously exposed for extended periods throughout the day over many years. This review aims to examine the various auditory and non-auditory outcomes associated with prolonged exposure to noise pollution.

MATERIALS AND METHODS

The review utilized a combination of relevant keywords to search the electronic databases. After screening based on the applied selection criteria for title, abstract, and full text, 44 articles were finally selected for critical review.

RESULTS

We identified and analyzed research findings related to noise-induced hearing loss, tinnitus, and sleep disturbances along with non-auditory issues such as annoyance, cognitive impairments, and mental stress associated with cardiovascular disorders. Furthermore, the existing studies were compared and collated to highlight the unique challenges and significance of noise pollution as a distinctive environmental concern and to explore the ongoing efforts in its research and prevention, including the early detection and potential reversal of noise-induced hearing loss.

CONCLUSION

The fundamental health consequences of noise pollution underscore the need for extensive research encompassing emerging noise sources and technologies to establish a health management system tailored to address noise-related health concerns and reduce noise exposure risk among populations. Finally, further research is warranted to ensure improved measurement of noise exposure and related health outcomes, especially in the context of occupational noise.

Tinnitus prevalence, associated characteristics, and related healthcare use in the United States: a population-level analysis

Background

Tinnitus is a potentially disabling condition with few treatments. We examined the prevalence and characteristics of tinnitus among demographic groups in the United States (US) and assessed associated factors and tinnitus-related healthcare.

Methods

We included adults with and without bothersome tinnitus from the nationally representative 2014 National Health Interview Survey (NHIS; raw n = 36,697), the latest year with tinnitus data. We evaluated tinnitus prevalence and characteristics (frequency, severity, duration) overall and among groups defined by sex and race/ethnicity. Logistic regression with adjusted Wald tests were used for comparisons in NHIS-weighted populations by sex and race/ethnicity, and to evaluate associations between demographic/medical characteristics and noise exposure on tinnitus risk.

Findings

The US prevalence of tinnitus was 11.2% (95% CI: 10.8%, 11.7%; ∼27 million people) in 2014. Of those with tinnitus, 41.2% always had symptoms and 28.3% had ≥15 years symptom duration; the rates were significantly higher among men vs. women and non-Hispanic (nHW) vs. Hispanic Whites (HW), Blacks, or other ethnicity. Significantly more women vs. men and HW vs. nHW reported severe tinnitus. Sex and race/ethnicity, except Asian, were not significantly associated with tinnitus when age, otologic/medical disorders, and noise exposure were included in the model. Significantly lower rates of all minority groups discussed tinnitus with a doctor compared to nHW, and among those who did, Blacks were significantly less likely to receive tinnitus evaluation than nHWs.

Interpretation

Tinnitus prevalence varies across US demographic groups and racial differences were identified in the delivery of tinnitus-related healthcare.

Funding

Rich Robbins, Bertarelli Foundation Endowed Professorship.

Magnitude of extended high frequency hearing loss associated with auditory related tinnitus distress, when controlling for magnitude of hearing loss at standard frequenciesa)

Impaired thresholds at extended high frequencies (EHF) are tightly linked to the prevalence of tinnitus, but little is known about how EHF status relates to tinnitus characteristics. In the present study, 93 individuals with tinnitus underwent standard (from 0.125 to 8 kHz) and EHF (from 10 to 16 kHz) audiometry and indicated their degree of tinnitus distress by completing the tinnitus functional index and their perceived tinnitus loudness by using a numeric rating scale. Partial correlation analyses indicated that the magnitude of EHF loss was significantly associated with degree of auditory related tinnitus distress (r = 0.343, p < 0.001) when controlling for pure tone average at standard frequencies and compensating for multiple testing. It is concluded that EHF status is related specifically to auditory related tinnitus distress, but not to intrusive-, sense of control-, cognitive-, sleep-, relaxation-, quality of life-, emotional-related tinnitus distress, total tinnitus distress, or perceived tinnitus loudness.

Current and Emerging Therapies for Chronic Subjective Tinnitus

IMPORTANCE

Chronic subjective tinnitus, the perception of sound without an external source for longer than six months, may be a greatly debilitating condition for some people, and is associated with psychiatric comorbidities and high healthcare costs. Current treatments are not beneficial for all patients and there is a large need for new therapies for tinnitus.

OBSERVATIONS

Unlike rarer cases of objective tinnitus, chronic subjective tinnitus often has no obvious etiology and a diverse pathophysiology. In the absence of objective testing, diagnosis is heavily based on clinical assessment. Management strategies include hearing aids, sound masking, tinnitus retraining therapy, cognitive behavioral therapy, and emerging therapies including transcranial magnetic stimulation and electrical stimulation.

CONCLUSIONS AND RELEVANCE

Although current treatments are limited, emerging diagnostics and treatments provide promising avenues for the management of tinnitus symptoms.

Targeting the Limbic System: Insights into Its Involvement in Tinnitus

Tinnitus is originally derived from the Latin verb tinnire, which means "to ring". Tinnitus, a complex disorder, is a result of sentient cognizance of a sound in the absence of an external auditory stimulus. It is reported in children, adults, and older populations. Patients suffering from tinnitus often present with hearing loss, anxiety, depression, and sleep disruption in addition to a hissing and ringing in the ear. Surgical interventions and many other forms of treatment have been only partially effective due to heterogeneity in tinnitus patients and a lack of understanding of the mechanisms of tinnitus. Although researchers across the globe have made significant progress in understanding the underlying mechanisms of tinnitus over the past few decades, tinnitus is still deemed to be a scientific enigma. This review summarises the role of the limbic system in tinnitus development and provides insight into the development of potential target-specific tinnitus therapies.

Traffic noise and adiposity: a systematic review and meta-analysis of epidemiological studies

Traffic noise has attracted much attention as a significant and intractable public health threat. This study was designed as a systematical review to explore the association of traffic noise with different indicators of obesity, thus providing updated quantitative estimates for the pooled effect estimates of the existing literature. We conducted an extensive search for epidemiological studies that investigated the association of traffic noise with obesity in three electronic databases till February 23, 2021. We used random-effects meta-analysis to calculate the summary effect estimates for each 10-dB(A) increase in noise and compared the highest with the lowest category of noise in relation to seven obesity indicators. Meanwhile, we assessed the risk of bias and the overall quality of the evidence of each study as well as the level of evidence for each exposure-outcome pair. The initial search identified 30 studies, 13 of which were ultimately included. The meta-analysis for the highest versus the lowest category of noise exposure was generally associated with higher waist circumfluence (WC) ranging from 0.326 cm (95% confidence interval (CI) = 0.078, 0.574) to 0.705 cm (95% CI = 0.071, 1.340) and higher odds of central obesity ranging from 1.055 (95% CI = 1.000, 1.109) to 1.167 (95% CI = 1.037, 1.298). When the continuous exposure (each 10 dB(A) increase in noise) was introduced, similar results were found. This study indicated positive associations of traffic noise with WC and central obesity. However, in consideration of some limitations, there is an urgent need for future studies to increase the sample size, discriminate the etiological differences in different noise and obesity indicators, and thoroughly consider socioeconomic status.

Effect of Electroacupuncture on Noise-Induced Hearing Loss in Rats

Acupuncture has long been used to relieve some inner ear diseases such as deafness and tinnitus. The present study examined the effect of electroacupuncture (EA) on noise-induced hearing loss (NIHL) in animals. A NIHL rat model was established. Electroacupuncture pretreatment at 2 Hz or posttreatment at the right Zhongzhu (TE3) acupoint was applied for 1 hour. Auditory thresholds were measured using auditory brainstem responses (ABRs), and histopathology of the cochlea was examined. The results indicated that the baseline auditory threshold of ABR was not significantly different between the control (no noise), EA-only (only EA without noise), noise (noise exposure only), pre-EA (pretreating EA then noise), and post-EA (noise exposure then posttreating with EA) groups. Significant auditory threshold shifts were found in the noise, pre-EA, and post-EA groups in the immediate period after noise exposure, whereas auditory recovery was better in the pre-EA and post-EA groups than that in the noise group at the three days, one week (W1), two weeks (W2), three weeks (W3), and four weeks(W4) after noise stimulation. Histopathological examination revealed greater loss of the density of spiral ganglion neurons in the noise group than in the control group at W1 and W2. Although significant loss of spiral ganglion loss happened in pre-EA and post-EA groups, such loss was less than the loss of the noise group, especially W1. These results indicate that either pretreatment or posttreatment with EA may facilitate auditory recovery after NIHL. The detailed mechanism through which EA alleviates NIHL requires further study.

Pollution, Inflammation, and Vaccines: A Complex Crosstalk

The importance of pollution in determining human health is becoming increasingly clear, also given the dramatic consequences it has had on recent geopolitical events. Yet, the consequences of contamination are not always straightforward. In this paper, we will discuss the effects of different pollutants on different aspects of human health, in particular on the immune system and inflammation. Different environmental pollutants can have different effects on the immune system, which can then promote complex pathologies, such as autoimmune disorders and cancer. The interaction with the microbiota also further helps to determine the consequences of contamination on wellbeing. The pollution can affect vaccination efficacy, given the widespread effects of vaccination on immunity. At the same time, some vaccinations also can exert protective effects against some forms of pollution.