Trends in worker hearing loss by industry sector, 1981-2010

Generational Differences in Audiometric and Self-Reported Hearing and Hearing Aid Use

PURPOSE

Birth cohort differences capture secular trends in population health. We aimed to determine birth cohort differences, defined by generation, in hearing-related outcomes.

METHODS

Participants were from a community-based cohort study. Generation was classified according to birth year: Greatest (1901-1924), Silent (1925-1945), Baby Boom (1946-1964), Generation X (1965-1980), or Millennial (1981-1996) and Gen Z (1997-2012). Primary outcomes were audiometric hearing loss, defined as a worse ear pure-tone average (PTA) of thresholds at frequencies 0.5, 1.0, 2.0, and 4.0 kHz > 25 dB HL, and self-reported hearing difficulty, defined as a score ≥ 6 on the Revised Hearing Handicap Inventory (RHHI). Analyses focused on hearing aid use included only participants with audiometric hearing loss. We used multivariable adjusted logistic regression models to evaluate associations between generation and each outcome. Models were stratified to sex when there was evidence of effect modification.

RESULTS

This cross-sectional study included 1554 participants (mean age 63.7 [SD 14.4] years; 56.8% female, 20.0% racial Minority). The prevalence of audiometric hearing loss, self-reported hearing difficulty, and hearing aid use (among participants with audiometric hearing loss) was 48.9%, 48.8%, and 22.0%, respectively. Generation was associated with audiometric hearing loss in the entire sample and males only. Generation was not consistently associated with self-reported hearing difficulty or hearing aid use.

CONCLUSION

More recent generations had lower prevalence of audiometric hearing loss. There were no generational differences in self-reported hearing difficulty or hearing aid use. Secular hearing-related trends can inform accurate projections of the burden of hearing loss and health care utilization.

Stakeholder perspectives on hearing conservation programmes in the South African mining sector: A qualitative study

PURPOSE

Stakeholders play a crucial role in the success of complex interventions, such as hearing conservation programmes (HCPs), where their active participation directly impacts outcomes. This study aimed to investigate the views of various stakeholders, involved in occupational noise management, in the mining sector in South Africa.

METHODS

A cross-sectional qualitative study was conducted, recruiting 16 participants through purposive and snowball sampling techniques. Participants represented diverse roles, including Mine Health and Safety officials, audiologists, ventilation and occupational health engineers and an occupational hygiene assistant. In-depth interviews were conducted to gather data, which were later analysed using inductive thematic analysis to identify emerging themes.

RESULTS

The in-depth interviews revealed six prominent themes that shed light on both the facilitators and barriers to achieving desired milestones in the implementation of HCPs. These themes were crisis management; some are more equal than others; we have tried, but then reality intervenes; cost of an individual's hearing; knowledge is power; and show and tell.

CONCLUSION

Achieving milestones requires a comprehensive and systematic approach, fostering collaborative engagement among all stakeholders in the mining industry. By viewing and treating HCPs as complex interventions, occupational healthcare can be improved for individuals exposed to excessive noise in the workplace. The study highlights the need for careful consideration of stakeholder perspectives to ensure the feasibility and effectiveness of interventions aimed at eliminating excessive noise in the mining industry.

Hearing Loss Is Associated With Increased Mortality in a Cohort of Older Construction Trades Workers

BACKGROUND

Hearing loss has been associated with increased mortality, and there is evidence that regular use of hearing aids reduces the mortality risk. However, these associations have not been sufficiently studied in worker populations at high risk for noise-induced hearing loss.

METHODS

Medical examination data for 19,379 workers employed in US Department of Energy (DOE) facilities were used. Speech-frequency pure-tone average hearing loss and hearing aid use were ascertained. Mortality status through 2021 was obtained from the National Death Index. Cox regression examined the association between hearing loss and mortality and the impact of hearing aid use.

RESULTS

Eight thousand eighty-one workers (41.3%) had speech-frequency hearing loss and 2228 (15.3%) of these workers reported use of hearing aids. A total of 5398 deaths occurred over a median follow-up of 11.1 years. Hearing loss was an independent risk factor for higher mortality with an adjusted hazard ratio (HR) of 1.10 (95% CI = 1.03-1.17). The HR increased with hearing loss severity but the relationship was non-linear. Hearing aid users were at 30% reduced risk of mortality compared to those not using hearing aids (HR = 0.70, 95% CI = 0.63-0.77).

CONCLUSIONS

Results are consistent with research linking hearing loss with increased mortality and the preventive impact of hearing aid use. These findings should inform workers' compensation programs in favor of: (1) better coverage of hearing loss for noise-exposed workers, and (2) inclusion of hearing aids in medical benefits. Reduction in noise exposures is a priority and workers with hearing loss should be encouraged to use hearing aids.

Prevalence of hearing loss among noise-exposed U.S. workers within the Construction sector, 2010-2019

BACKGROUND

The purpose of this cross-sectional study is to estimate the prevalence of hearing loss among noise-exposed U.S. workers during 2010-2019 within the Construction sector.

METHODS

Audiograms for 26,653 workers at 833 Construction companies (and for 1.3 million other workers) were examined. Period prevalence and adjusted risk for hearing loss as compared with a reference industry (Couriers and Messengers) were estimated for the Construction sector and sub-sectors, and all industries combined.

RESULTS

The prevalence of hearing loss within the Construction sector was 23% compared to 20% for all industries combined. Several sub-sectors exceeded the overall prevalence and all but two had adjusted risks significantly higher than the reference industry. The sub-sectors with the highest prevalences for hearing loss were: Highway, Street, and Bridge Construction (28%), Site Preparation Contractors (26%), New Single-Family Housing Construction (except Operative Builders) (25%), Oil and Gas Pipeline and Related Structures Construction (25%), and Other Building Finishing Contractors (25%). The sub-sectors with the highest adjusted risks were Industrial Building Construction; Other Heavy and Civil Engineering Construction; Oil and Gas Pipeline and Related Structures Construction; Finish Carpentry Contractors; and Site Preparation Contractors; with risks 62%, 61%, 60%, 59% and 58% higher than the reference industry, respectively.

CONCLUSIONS

Hearing loss continues to be a significant issue within Construction. Reducing noise exposure is critical, including buying quieter equipment, keeping moving parts oiled and well-maintained, enclosing noise sources, and employing administrative controls to reduce the number of workers in noisy areas. Barriers to workers consistently and correctly wearing their hearing protection also need to be addressed.

PRACTICAL APPLICATIONS

Within Construction, hazardous noise is common and the risk of hearing loss is high. This study identified the Construction sub-sectors with the highest prevalences and risks to guide interventions toward workers most in need of prevention and described strategies for reducing exposures.

Wearing Hearing Protection Makes Me Worse at My Job: Impacts of Hearing Protection Use on Sensorimotor Tracking Performance

OBJECTIVES

Occupational hearing loss is a significant problem worldwide despite the fact that it can be mitigated by the wearing of hearing protection devices (HPDs). When surveyed, workers frequently report that worsened work performance while wearing HPDs is one reason why they choose not to wear them. However, there have been few studies to supplement these subjective reports with objective measures. Where they do exist, assessed performance measures have mostly characterized auditory situational awareness in gross terms (e.g., average speech comprehension scores over an entire session). The temporal dynamics of performance and HPD impacts on nonauditory aspects of work performance are largely unknown. In the present study, we aimed to fill this gap in the literature by measuring how HPD usage impacted sensorimotor tracking performance in relation to ongoing auditory events.

DESIGN

In two experiments, listeners heard commands sourced from the coordinate response measure (CRM) corpus (i.e., sentences of the form "Ready go to now"). These commands informed listeners of which of nine moving on-screen objects to track with a computer mouse (e.g., "blue four" refers the listener to a blue square). The commands were presented in background street noise and were heard under either "No HPD" or "HPD" conditions. In experiment 1, HPD wearing was simulated with a digital filter designed to mimic the attenuation profile of a passive HPD. In experiment 2, actual HPDs were worn by listeners. Continuous recording of tracking error allowed us to simultaneously examine how HPD wearing impacted speech comprehension, the accuracy of tracking, and how tracking accuracy varied as a function of time on task and ongoing auditory events (e.g., the presentation of a critical CRM sentence).

RESULTS

In both experiments, listeners spent less time tracking the correct object in the HPD condition. After trimming data to those time points in which the target object was known, worse performance was exhibited by the HPD condition than the No HPD condition. In the examination of the temporal dynamics of tracking error, it was apparent that differences arose strongly during the presentation of CRM sentences.

CONCLUSIONS

Workers' complaints of poorer performance while wearing HPDs are justified and extend beyond just diminished auditory situational awareness. The negative impact on nonauditory aspects of work performance may be strongest around critical listening periods. Addressing these aspects of performance will be an important part of addressing HPD nonuse in occupational settings.

Nationwide Hearing Loss Trends Over Two Decades

OBJECTIVES

Hearing loss (HL) is one of the most common chronic health conditions in the United States (US). This study aims to evaluate trends in HL prevalence among US adults over the past two decades.

METHODS

Audiometric data of adults from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018 were analyzed in 2-year intervals to evaluate changes in HL (defined as pure tone average greater than 25 dB in at least one ear) over time in using odds ratios (ORs). Multivariate logistic regression was used to control for age and sex, and linear regression was used to evaluate trends in HL prevalence over time.

RESULTS

The study included 13,468 participants. In adult participants (20-69 years old), HL remained stable over time, with some fluctuations ranging from 14.8% to 16.8%. In elderly participants (70-years and older), HL remained stable over time, with some fluctuations ranging from 71.7% to 77.1%. Based on univariate and linear regression analysis, there were no differences in HL rates in the adult and elderly cohorts. Subjects 40-49 years old and adults with education level of less than high school had significant downward trends in HL prevalence over two decades (p < 0.001 and p = 0.029).

CONCLUSIONS

HL prevalence may be declining in the adult population when correcting for age and gender; however, there has not been a significant downward trend for the elderly population. HL may be decreasing over time among adults 40-49 years old and with shorter education backgrounds.

LEVEL OF EVIDENCE

4 Laryngoscope, 135:277-285, 2025.

Construction Site Noise Exposure Assessment Using Binaural Measurements and Analysis

Acoustic measures of construction site noise are important for hearing loss prevention and safety. This work examines noise exposure assessment using binaural measurements to pave the way for more accurate noise characterization and hearing loss prevention in loud workplaces. Recordings were made over three days on a construction site, and noise exposure was estimated using state-of-the-art methods (a shoulder-worn dosimeter) and binaural measurements (microphones at each ear). For the binaural assessment, noise exposure was quantified at each ear to identify the higher- and lower-exposure ears, and the assessment incorporated kurtosis, a statistical measure that quantifies impulsiveness of the noise. The impulsiveness of the noise of four construction tools was also assessed. For this set of measurements, traditional hearing loss risk assessment consistently underestimated the noise exposure relative to binaural assessment. Moreover, the binaural measurement method exposed multiple cases of asymmetric noise exposure that are not detectable using the traditional method. Overall, there are clear benefits to assessing risk using binaural measurements and more detailed analysis methods.

Relationship Between Occupational Exposure to Noise and Vibrations and Vertigo: A Prospective Case-Control Study

Background/Objectives: It is known that balance disorders involve occupational hazards. However, the inverse relationship (between certain occupations and an increased incidence of vertigo or dizziness) has been scarcely studied. The objective of this work was to analyze the occupation of a group of patients with vertigo compared to the economically active general population and to evaluate the prevalence of occupational noise and/or vibration exposure in both groups. Methods: A prospective cross-sectional, observational, case-control study was carried out, including 393 patients (193: Meniere's disease; 63: vestibular migraine; 21: vestibular neuritis; 116: BPPV) (244 women and 149 men). These patients were compared to a control group from the general population obtained from 6th EWCS-Spain (2015). Possible differences regarding sex, age, occupation, exposure to noise, and exposure to mechanical vibrations were analyzed. Results: Differences in the distribution of occupations between patients with vertigo and the general population were observed (Chi-square, p = 4.065 × e-20). Patients with vertigo were significantly more exposed to noise (Fisher's exact test, p = 2.97 × e-10; OR = 2.595, CI95% (1.916;3.515)) and vibrations (Fisher's exact test, p = 6.23 × e-10; OR = 2.722, CI95% (1.963;3.775)) than the control group. These differences were observed both between men and women. Conclusions: A relationship between occupational exposure to noise and/or vibrations and the presence of vertigo was observed. Protective and preventive measures could help prevent the occurrence of some diseases involving vertigo.

Development of an artificial intelligence based occupational noise induced hearing loss early warning system for mine workers

Introduction

Occupational Noise Induced Hearing Loss (ONIHL) is one of the most prevalent conditions among mine workers globally. This reality is due to mine workers being exposed to noise produced by heavy machinery, rock drilling, blasting, and so on. This condition can be compounded by the fact that mine workers often work in confined workspaces for extended periods of time, where little to no attenuation of noise occurs. The objective of this research work is to present a preliminary study of the development of a hearing loss, early monitoring system for mine workers.

Methodology

The system consists of a smart watch and smart hearing muff equipped with sound sensors which collect noise intensity levels and the frequency of exposure. The collected information is transferred to a database where machine learning algorithms namely the logistic regression, support vector machines, decision tree and Random Forest Classifier are used to classify and cluster it into levels of priority. Feedback is then sent from the database to a mine worker smart watch based on priority level. In cases where the priority level is extreme, indicating high levels of noise, the smart watch vibrates to alert the miner. The developed system was tested in a mock mine environment consisting of a 67 metres tunnel located in the basement of a building whose roof top represents the "surface" of a mine. The mock-mine shape, size of the tunnel, steel-support infrastructure, and ventilation system are analogous to deep hard-rock mine. The wireless channel propagation of the mock-mine is statistically characterized in 2.4-2.5 GHz frequency band. Actual underground mine material was used to build the mock mine to ensure it mimics a real mine as close as possible. The system was tested by 50 participants both male and female ranging from ages of 18 to 60 years.

Results and discussion

Preliminary results of the system show decision tree had the highest accuracy compared to the other algorithms used. It has an average testing accuracy of 91.25% and average training accuracy of 99.79%. The system also showed a good response level in terms of detection of noise input levels of exposure, transmission of the information to the data base and communication of recommendations to the miner. The developed system is still undergoing further refinements and testing prior to being tested in an actual mine.

Workplace concentrations of particulate matter and noise levels among stone quarry and soil brick-making workers in Tanzania

This study was conducted in 15 artisanal stone quarries (SQ) and 22 soil brick-making (SBM) sites. Specific objectives were to: (i) quantify ambient concentrations of suspended particulate matter (PM) and gaseous pollutants and noise levels at SQ and SBM workplaces; (ii) critically evaluate the potential workplace hazards, and risk factors; and (iii) analyze potential health risks to workers. Gaseous pollutants, PM, and noise levels were measured by using portable digital devices. Social demographic information of 150 workers across the study sites was collected using a questionnaire. Quantitative data were summarized and exploratorily analyzed using Stata software. This study revealed that fuel burning in the SBM releases SPM up to 10-fold and CO gas up to 14-fold above the WHO-recommended time-weighted average exposure concentrations of 16.6 µg/m3 and 0.3 mg/m3, respectively. On average hitting with a pickax in SQ areas released noise levels of about 81.01 ± 6.8 dB[A]. Overall, the SQ and SBM workers were exposed to low concentrations of PM and noise levels when the measurements were taken. Long working hours for repetitive activities in hot-sunny (27.1 ± 2.3 °C) and low outdoor humidity 23 ± 1.5%, potentially increase epidemiological risks to vulnerable individuals and enhance worker exposures to inhalable PMs. Although workplace noise exposure below the regulatory threshold of 85 dB[A] may not cause immediate hearing damage, it can have a significant impact on workers' hearing health, cognitive performance, psychological well-being, and overall productivity. This study provides an overview of workplace conditions rather than an accurate representation of the actual worker exposure levels because personal breathing zone sampling devices were not used. This study provides baseline information for further research and can be used for evidence-based decision-making and policy formulation to safeguard worker safety and health in SQ and SBM sites in Tanzania.

Noise-Induced Hearing Threshold Shift Correlated with Body Weight and External-Ear Amplification in Chinchilla: a Preliminary Analysis

BACKGROUND

External-ear amplification (EEA) has been shown to vary from 5-19 dB-A in large datasets of pediatric, adolescent, and adult human participants. However, variable EEA is an overlooked characteristic that likely plays a role in individual noise-induced hearing loss (NIHL) susceptibility. A noise exposure varying 5-19 dB-A translates to high-EEA individuals theoretically experiencing 3-4 times greater NIHL risk than low-EEA individuals.

OBJECTIVE

The purpose of this preliminary analysis was to test the hypothesis that higher EEA is correlated with increased noise-induced threshold shift susceptibility.

DESIGN

Nine chinchillas were exposed to 4-kHz octave-band noise at 89 dB-SPL for 24 h. Auditory brainstem response thresholds were obtained pre-exposure, 24-h post-exposure, and 4-week post-exposure. Relationships between EEA and threshold shift were analyzed.

RESULTS

Open-ear EEA ranged 11-19 dB-SPL, and occluded-ear EEA ranged 10-21 dB-SPL. Higher occluded-ear EEA was correlated with increased NIHL susceptibility (p = 0.04), as was lower body weight (p = 0.01). Male animals exhibited more threshold shift than female animals (p = 0.02), lower body weight than female animals (p = 0.02), and higher occluded-ear EEA (male mean = 18 dB; female mean = 15 dB).

CONCLUSIONS

Taken together, increased threshold shift susceptibility was observed in the smallest animals, animals with the highest occluded-ear EEA, and in male animals (which tended to have higher occluded-ear EEA). Given the established relationship between smaller body size and higher occluded-ear EEA, these preliminary results suggest that body size (and occluded-ear EEA; a function of body size) could be a potential, underlying driver of NIHL susceptibility differences, rather than true sex differences.

Preventing Occupational Hearing Loss: 50 Years of Research and Recommendations from the National Institute for Occupational Safety and Health

For more than 50 years, the National Institute for Occupational Safety and Health (NIOSH), part of the United States (U.S.) Centers for Disease Control and Prevention (CDC), has been actively working to reduce the effects of noise and ototoxic chemicals on worker hearing. NIOSH has pioneered basic and applied research on occupational hearing risks and preventive measures. The Institute has issued recommendations and promoted effective interventions through mechanisms ranging from formal criteria documents to blogs and social media. NIOSH has conducted surveillance and published statistics to guide policy and target prevention efforts. Over the past five decades, substantial progress has been made in raising awareness of noise as a hazard, reducing the risk of occupational hearing loss, improving the use of hearing protection, and advancing measurement and control technologies. Nevertheless, noise remains a prevalent workplace hazard and occupational hearing loss is still one of the most common work-related conditions. NIOSH continues to work toward preventing the effects of noise and ototoxicants at work and has many resources to assist audiologists in their hearing loss prevention efforts.

Evaluating the potential impact of ototoxicant exposure on worker health

Occupational exposure to ototoxicants, substances that can cause hearing loss alone or exacerbate hearing loss when exposure occurs in combination with noise, is a workplace hazard that is poorly understood. A review of existing research indicates that some solvents and heavy metals may be ototoxic, but few studies have attempted to estimate the impact of ototoxicant exposure on the United States worker population. Researchers examined trends in workplace exposure to ototoxicants among workers in the United States by comparing exposure data collected by the Occupational Safety and Health Administration against worker hearing loss data provided by the Bureau of Labor Statistics (BLS) for 2012-2019. The study found that the noise exposure data was strongly correlated to the hearing loss data using Pearson's correlation (p < .001), confirming that the exposure data collected by OSHA is predictive of the risk of occupational illness as reported by BLS. Chi-square analysis indicates that reported hearing loss was more common among industry subsectors with exposure to ototoxicants than those without exposure to ototoxicants. These findings suggest that workers with coexposure to ototoxicants and noise may be at a higher risk of experiencing hearing loss than those exposed to noise alone, and action should be taken to minimize this risk.

Health conditions among male workers in mining and other industries reliant on manual labor occupations: National Health Interview Survey, 2007-2018

INTRODUCTION

Mining is an industry with diverse, demanding occupational exposures. Understanding the prevalence of chronic health conditions in working miners is an area of active research. Of particular interest is how the health of miners compares to that of workers in other industry sectors with a high proportion of manual labor occupations. By comparing similar industries, we can learn what health conditions may be associated with manual labor and with individual industries. This study analyzes the prevalence of health conditions in miners compared to workers employed in other manual-labor-reliant industries.

METHODS

National Health Interview Survey public data were analyzed for the years 2007-2018. Mining and five other industry groups with a high proportion of manual labor occupations were identified. Female workers were excluded because of small sample sizes. The prevalence of chronic health outcomes was calculated for each industry group and compared to that of nonmanual labor industries.

RESULTS

Currently-working male miners showed increased prevalence of hypertension (in those age <55 years), hearing loss, lower back pain, leg pain progressing from lower back pain, and joint pain, compared to nonmanual labor industries workers. Construction workers also demonstrated a high prevalence of pain.

CONCLUSION

Miners demonstrated increased prevalence of several health conditions, even when compared to other manual labor industries. Given previous research on chronic pain and opioid misuse, the high pain prevalence found among miners suggests mining employers should reduce work factors that cause injury while also providing an environment where workers can address pain management and substance use.

Prevalence of Disability by Occupation Group - United States, 2016-2020

In 2020, approximately 21.5 million employed U.S. adults aged 18-64 years had some form of disability. Although 75.8% of noninstitutionalized persons without disability aged 18-64 were employed, only 38.4% of their counterparts with disability were employed (1). Persons with disability have job preferences similar to persons without disability but might encounter barriers (e.g., lower average training or education levels, discrimination, or limited transportation options) that affect the types of jobs they hold (2,3). CDC analyzed 2016-2020 Behavioral Risk Factor Surveillance System (BRFSS) data from 35 states and Guam to estimate disability prevalences, by type and occupation group, among currently employed U.S. adults aged 18-64 years. The highest adjusted disability prevalences were among workers in three of the 22 major occupation groups: food preparation and serving-related (19.9%); personal care and service (19.4%); and arts, design, entertainment, sports, and media (17.7%). Occupation groups with the lowest adjusted disability prevalences were business and financial operations (11.3%), health care practitioners and technicians (11.1%), and architecture and engineering (11.0%). The distributions of persons with and without disability differ across occupations. Workplace programs that address the training, education, and workplace needs of employees with disability might improve workers' ability to enter, thrive in, and advance in a wider range of occupations.

Noise exposure assessment of non-coal mining workers in four provinces of China

Objective

This study aimed to understand the noise exposure of non-coal mines in China to take appropriate controls to protect workers' health.

Methods

An assessment of non-coal miners' noise exposures was conducted in four provinces in China. Individual noise exposure levels were measured, and the survey on the hearing protector device (HPD) equipment was administered.

Results

423 noise dosimeter measurements were obtained, including drilling, blasting, ore drawing, transportation, winching, crushing, screening and ball milling, and auxiliary (air pressure, pump, and maintenance). A total of 31.9% of the individual noise levels (L_EX,8h) exceeded 85 dB(A), and the median dosages of non-coal miners with high noise exposure were: excavation workers-89.1 dB(A), mill operators-88.7 dB(A), and crusher operators-87.0 dB(A). The noise dose of underground mine workers is higher than that of surface mine workers (P < 0.001). A total of 53.7% of non-coal mining enterprises are not equipped with HPD for workers, mainly small and micro enterprises.

Conclusions

High levels of hazardous noise exposure are typical in non-coal mines. Noise exposure data can help to develop more feasible noise controls.

How much have adverse occupational health outcomes among construction workers improved over time? Evidence from 25 years of medical screening

BACKGROUND

Construction workers have always had a high risk of occupational illnesses. We used 25 years of data from a medical screening program serving older construction workers to determine how much health outcomes have improved over the past 60 years.

METHODS

We investigated changes in relative risk for chest radiographs consistent with pneumoconiosis, COPD by spirometry, lung cancer mortality, and audiometry-assessed hearing impairment among workers participating in a medical screening program. Results were stratified by decade of first construction employment: before 1960, 1960-1969, 1970-1979, 1980-1989, and after 1990. Poisson and Cox regression analyses assessed relative risk by decade adjusted for age, sex, smoking, and years of construction trade work.

RESULTS

Subjects were 94% male and, on average, 60 years old with 25 years of construction work. When compared to workers employed before 1960, those first employed after 1990 experienced the following reductions in model-adjusted relative risks: chronic obstructive pulmonary disease, 32%; all pneumoconiosis, 68%; parenchymal abnormalities, 35%; pleural abnormalities, 71%; hearing impairment, 20%; and lung cancer mortality, 48%. Risks started to decline in the 1960s with greatest reductions among workers first employed after 1970.

CONCLUSIONS

This study demonstrates the positive impact that adoption of occupational health protections have had over the past 60 years. The greatest risk reductions were observed for outcomes with strong regulatory and legal incentives to reduce exposures and associated risks, such as those associated with inhalation hazards (asbestos and silica), while lowest improvement was for hearing impairment, for which little regulatory enforcement and few prevention incentives have been adopted.

Occupation and 20-year hearing decline: findings from The HUNT Study

BACKGROUND

Studies show that certain occupations are associated with an increased risk of hearing loss. However, many studies are cross-sectional, and the few longitudinal studies are mostly small or focus on only one occupation.

AIMS

We aimed to quantify the long-term hearing decline among workers in different occupations and assess whether the change differs between the occupations.

METHODS

The study population was 4525 adults who participated in two population-based health studies in Norway, HUNT2 1996-1998 and HUNT4 2017-2019. Linear regression models assessed the association between occupations (clerks as reference) and 20-year hearing decline (hearing thresholds at 3-6 kHz, averaged over both ears) from HUNT2 to HUNT4. Models were adjusted for age, sex, recurrent ear infections, smoking and ear pathology.

RESULTS

Among the participants (40% men), the mean age at HUNT2 was 31.2 ± 5.4 years (range 20-39) and the average 20-year hearing decline was 11.3 ± 9.8 dB. Occupations that were associated with larger hearing decline included other craft and related trades workers (3.9 dB, 95% confidence interval [CI] 0.2-7.7) and building frame and related trades workers (3.4 dB, 95% CI 1.3-5.4). Among occupations with larger hearing decline, a higher proportion of the workers reported exposure to noise.

CONCLUSIONS

This large longitudinal study shows a larger long-term hearing decline among building frame workers and craft and related trades workers. Differences between occupations were modest, which may indicate successful preventive measures in Norway during the last two decades.

Evaluation of a wearable consumer noise measurement device in a laboratory setting

Exposure to noise occurs throughout daily life and, depending on the intensity, duration, and context, can lead to hearing loss, disturbed sleep, decreased academic achievement, and other negative health outcomes. Recently, smartwatches that use the device's onboard microphone to measure noise levels were released. This study evaluated the accuracy of these smartwatches in a controlled laboratory setting. For broadband pink noise, a total of 11 441 measurements were collected. The results showed that, on average, the smartwatch reported 3.4 dBA lower than the reference system on average. For the octave-band, a total of 18 449 measurements were collected. The smartwatch measured lower than the reference microphone from the 125 Hz to 1000 Hz octave bands, were somewhat in agreement at 2000 Hz, measured higher sound pressure levels than the reference microphone at 4000 Hz, and then lower at 8000 Hz. Despite not meeting the ANSI criteria for sound level meters, in some cases, these smartwatches still provide a reasonable degree of accuracy and have the potential for use in studies that require the measurement of personal noise exposure over an extended period.

Beware the Grizzlyman: A comparison of job- and industry-based noise exposure estimates using manual coding and the NIOSH NIOCCS machine learning algorithm

Recently, the National Institute for Occupational Safety and Health (NIOSH) released an updated version of the NIOSH Industry and Occupation Computerized Coding System (NIOCCS), which uses supervised machine learning to assign industry and occupational codes based on provided free-text information. However, no efforts have been made to externally verify the quality of assigned industry and job titles when the algorithm is provided with inputs of varying quality. This study sought to evaluate whether the NIOCCS algorithm was sufficiently robust with low-quality inputs and how variable quality could impact subsequent job estimated exposures in a large job-exposure matrix for noise (NoiseJEM). Using free-text industry and job descriptions from >700,000 noise measurements in the NoiseJEM, three files were created and input into NIOCCS: (1) N1, "raw" industries and job titles; (2) N2, "refined" industries and "raw" job titles; and (3) N3, "refined" industries and job titles. Standardized industry and occupation codes were output by NIOCCS. Descriptive statistics of performance metrics (e.g., misclassification/discordance of occupation codes) were evaluated for each input relative to the original NoiseJEM dataset (N0). Across major Standardized Occupational Classifications (SOC), total discordance rates for N1, N2, and N3 compared to N0 were 53.6%, 42.3%, and 5.0%, respectively. The impact of discordance on the major SOC group varied and included both over- and under-estimates of average noise exposure compared to N0. N2 had the most accurate noise exposure estimates (i.e., smallest bias) across major SOC groups compared to N1 and N3. Further refinement of job titles in N3 showed little improvement. Some variation in classification efficacy was seen over time, particularly prior to 1985. Machine learning algorithms can systematically and consistently classify data but are highly dependent on the quality and amount of input data. The greatest benefit for an end-user may come from cleaning industry information before applying this method for job classification. Our results highlight the need for standardized classification methods that remain constant over time.

Audiometric data analysis for prevention of noise-induced hearing loss: A new approach

Compliance with noise regulations in the past three decades has significantly reduced workplace noise exposures, particularly in the loudest industries and occupations. However, the overall effectiveness of hearing conservation programs in preventing occupational noise-induced hearing loss remains uncertain and unquantified, while the incidence and cost of occupational hearing loss remain inexplicably high. This review/commentary critically explores this paradox by examining why the billions of annual audiograms conducted worldwide have not been aggregately utilized or applied to predict early NIHL in groups of workers or to measure the efficacy of exposure controls. Principal contributory reasons include regulation of noise as a safety standard rather than as a health standard, the inherent complexity of audiometric data, and the lack of a standardized method of interpretation for audiograms. The unsuccessful history of efforts to develop and adopt methods and tools to analyze aggregate audiometric data is described. Consequently, the Standard Threshold Shift-a regulatorily defined, lagging indicator of individual, irreversible hearing loss that is not an effective preventive metric-remains the de facto standard of care. A population-based Best Practices approach is proposed to leverage the raw audiometric data already available and turn it into actionable data for effective secondary prevention to strategically manage and reduce occupational hearing loss risk. This approach entails statistical methods and information management tools necessary to transform audiometry from a compliance-driven, individual screening test with limited preventive capability into a medical surveillance process directly linked to aggregate corrective and prevention actions.

Time-Trends of U.S. Occupational Noise Standard Violations by OSHA Region and Industry Type 1972 to 2019

OBJECTIVE

We examined time-trends in Occupational Noise Standard violations by OSHA region and industry type over 48 years.

METHODS

Along with descriptive analysis of original data, negative binomial regression and Poisson regression were applied to the analysis of 1972 to 2019 and 1972 to 2012 data, respectively.

RESULTS

A small annual decrease in violation units over the periods was revealed. The three analyses produced differing timetrends. The manufacturing industry had more violations, and Region 4 had the most violations. Regarding numbers of units, the 10 regions and 2 industries were jointly significant. Some interaction between regions and industry types appeared in both regressions.

CONCLUSIONS

OSHA should specify how many regions report noise violations each year to ensure accurate identification of noise-related health risks to American workers. Further time-trend studies are needed for specific regions and industry types.

Hearing loss and hypertension among noise-exposed workers: a pilot study based on baseline data

This study aimed to assess the prevalence of noise-induced hearing loss (NIHL) and hypertension, and the association between NIHL and hypertension using occupational physical examination data of 42,588 noise-exposed workers from local enterprises in Yangzhou between 2015 and 2017. The average binaural high-frequency threshold on average (BHFTA), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were 23.09 ± 11.32 dB, 126.85 ± 15.94 mm Hg and 79.94 ± 11.61 mm Hg. The prevalence of NIHL and hypertension were 24.38% and 25.40%. An increased risk of NIHL and hypertension was observed in the groups of males, aged >35 years, noise exposure time >5 years, noise exposure level >85 dB(A) and smoking. 32.25% NIHL workers had hypertension. NIHL workers were at higher risk of hypertension (adjusted OR = 1.07, 95%CI = 1.02-1.13). This study shows that the noise-exposed workers have high risk of developing NIHL and hypertension.

A Design Method for Gammachirp Filterbank for Loudness Compensation in Hearing Aids

Because the hearing impaired often experience different degrees of hearing loss along with the loss of frequencies, the loudness compensation algorithm in hearing aids decomposes the speech signal and compensates with different frequency bands based on their audiograms. However, the speech quality of the compensated signal is unsatisfactory because the traditional filterbanks fail to fully consider the characteristics of human hearing and personalized hearing loss. In this study, an effective design for the gammachirp filterbank for the loudness compensation algorithm was proposed to improve the speech quality of hearing aids. Firstly, a multichannel gammachirp filterbank was employed to decompose the signals. Then, the adjacent bands were merged into one channel, guided by the proposed combination method. After obtaining the personalized filterbank, each band conducted a loudness compensation to match the requirements of the audiograms. The excellent advantage of the gammachirp filterbank is that it can simulate the characteristics of the basilar membrane. Furthermore, the novel channel combination method considers the information from the audiograms and the relationship between frequency ranges and speech intelligibility. The experimental results showed that the proposed multichannel gammachirp filterbank achieves better speech signal decomposition and synthesis, and good performance can be gained with fewer channels. The loudness compensation algorithm based on the gammachirp filterbank effectively improves sentence intelligibility. The sentence recognition rate of the proposed method is higher than that of a system with a gammatone filterbank by approximately 13%.

Occupational Health and Safety Statistics as an Indicator of Worker Physical Health in South African Industry

Operations in general industry, including manufacturing, expose employees to a myriad of occupational health hazards. To prevent exposure, occupational health and safety regulations were enacted, with both employers and workers instituting various risk reduction measures. The analysis of available occupational disease and injury statistics (indicators of worker physical health) can be used to infer the effectiveness of risk reduction measures and regulations in preventing exposure. Thus, using the READ approach, analyses of occupational disease and injury statistics from South African industry, derived from annual reports of the Compensation Fund, were conducted. The publicly available database of occupational disease and injury statistics from the South African general industry is unstructured, and the data are inconsistently reported. This data scarcity, symptomatic of an absence of a functional occupational disease surveillance system, complicates judgement making regarding the effectiveness of implemented risk reduction measures, enacted occupational health and safety regulations and the status of worker physical health from exposure to workplace hazards. The statistics, where available, indicate that workers continue to be exposed to occupational health impacts within general industry, notwithstanding risk reduction measures and enacted regulations. In particular, worker physical health continues to be impacted by occupational injuries and noise-induced hearing loss. This is suggestive of shortcomings and inefficiencies in industry-implemented preventive measures and the regulatory state. A robust national occupational disease surveillance system is a regulatory tool that should detect and direct policy responses to identified occupational health hazards.

Guidelines for Diagnosing and Quantifying Noise-Induced Hearing Loss

This paper makes recommendations for the diagnosis and quantification of noise-induced hearing loss (NIHL) in a medico-legal context. A distinction is made between NIHL produced by: steady broadband noise, as occurs in some factories; more impulsive factory sounds, such as hammering; noise exposure during military service, which can involve very high peak sound levels; and exposure to very intense tones. It is argued that existing diagnostic methods, which were primarily developed to deal with NIHL produced by steady broadband noise, are not adequate for the diagnosis of NIHL produced by different types of exposures. Furthermore, some existing diagnostic methods are based on now-obsolete standards, and make unrealistic assumptions. Diagnostic methods are proposed for each of the types of noise exposure considered. It is recommended that quantification of NIHL for all types of exposures is based on comparison of the measured hearing threshold levels with the age-associated hearing levels (AAHLs) for a non-noise exposed population, as specified in ISO 7029 (2017), usually using the 50th percentile, but using another percentile if there are good reasons for doing so. When audiograms are available both soon after the end of military service and some time afterwards, the most recent audiogram should be used for diagnosis and quantification, since this reflects any effect of the noise exposure on the subsequent progression of hearing loss. It is recommended that the overall NIHL for each ear be quantified as the average NIHL across the frequencies 1, 2, and 4 kHz.

Area Noise Assessment at Surface Stone, Sand, and Gravel Mines: Application for Reducing Worker Noise Exposure

Repeated noise exposure and occupational hearing loss are common health problems across industries and especially within the mining industry. Large mechanized processes, blasting, grinding, drilling, and work that is often in close quarters put many miners at an increased risk of noise overexposure. In stone, sand, and gravel mining, noise is generated from a variety of sources, depending on the type of ore being mined as well as the final consumer product provided by that mine. Depending on the source of noise generation, different strategies to reduce and avoid that noise should be implemented. The National Institute for Occupational Safety and Health (NIOSH) has evaluated the noise profile at three operational surface stone, sand, and gravel mines. A-weighted sound level meter data as well as phase array beamforming data were collected throughout the mines in areas with high noise exposure or high personnel foot or vehicle traffic. Sound level meter data collected on a grid pattern was used to develop sound profiles of the working areas. These sound contour maps as well as phase array beamforming plots were provided to the mines as well as guidance to modify work areas or personnel traffic to reduce noise exposure.

Pure Tone Audiometry Evaluation Method Effectiveness in Detecting Hearing Changes Due to Workplace Ototoxicant, Continuous Noise, and Impulse Noise Exposures

OBJECTIVES

The purpose of this retrospective cohort study was to compare the relative risks (RR) of hearing impairment due to co-exposure of continuous noise, impulse noise, metal ototoxicants, and organic solvent ototoxicants using several pure tone audiometry (PTA) evaluation methods.

DESIGN

Noise and ototoxicant exposure and PTA records were extracted from a DoD longitudinal repository and were analyzed for U.S. Air Force personnel (n = 2372) at a depot-level aircraft maintenance activity at Tinker Air Force Base, Oklahoma using an historical cohort study design. Eight similar exposure groups based on combinations of ototoxicant and noise exposure were created: (1) Continuous noise (reference group); (2) Continuous noise + Impulse noise; (3) Metal exposure + Continuous noise; (4) Metal exposure + Continuous noise + Impulse noise; (5) Solvent exposure + Continuous noise; (6) Solvent exposure + Continuous noise + Impulse noise; (7) Metal exposure + Solvent exposure + Continuous noise; and (8) Metal exposure + Solvent exposure + Continuous noise + Impulse noise. RR of hearing impairment compared to the Continuous noise-exposed reference group was assessed with five PTA evaluation methods including (1) U.S. Department of Defense (DoD) Significant Threshold Shift (STS), (2) Occupational Safety and Health Administration (OSHA) age-adjusted STS, (3) National Institute for Occupational Safety and Health (NIOSH) STS, (4) NIOSH Material Hearing Impairment, and (5) All Frequency Threshold Average.

RESULTS

Hearing impairment was significantly worse for SEG (2) combined exposure to continuous noise and impulse noise only for the PTA evaluation method (2) OSHA Age Adjusted with an RR of 3.11, [95% confidence interval (CI), 1.16-8.31] and was nearly significantly different using PTA evaluation method (4) NIOSH Material Hearing Impairment with an RR of 3.16 (95% CI, 0.99-10.15). Despite no significant differences for SEGs with an ototoxicant exposure, PTA evaluation method (3) NIOSH STS was most sensitive in detecting hearing changes for SEG (8) Metal exposure + Solvent exposure + Continuous noise + Impulse noise as demonstrated by a RR of 1.12 (95% CI, 0.99-1.27).

CONCLUSIONS

Results suggest that a single PTA evaluation technique may not be adequate in fully revealing hearing impairment risk due to all stressors and tailoring the PTA evaluation technique to the hazards present in the workplace could better detect hearing impairment. Additionally, results suggest that PTA may not be effective as the sole technique for evaluating hearing impairment due to ototoxicant exposure with continuous noise co-exposure.

Applying Kurtosis as an Indirect Metric of Noise Temporal Structure in the Assessment of Hearing Loss Associated With Occupational Complex Noise Exposure

OBJECTIVE

The association of occupational noise-induced hearing loss (NIHL) with noise energy was well documented, but the relationship between occupational noise and noise temporal structure is rarely reported. The objective of this study was to investigate the principal characteristics of the relationship between occupational NIHL and the temporal structure of noise.

METHODS

Audiometric and shift-long noise exposure data were collected from 3102 Chinese manufacturing workers from six typical industries through a cross-sectional survey. In data analysis, A-weighted 8-h equivalent SPL (LAeq.8h), peak SPL, and cumulative noise exposure (CNE) were used as noise energy indicators, while kurtosis (β) was used as the indicator of noise temporal structure. Two NIHL were defined: (1) high-frequency noise-induced hearing loss (HFNIHL) and (2) noise-induced permanent threshold shift at test frequencies of 3, 4, and 6 kHz (noise-induced permanent threshold shift [NIPTS346]). The noise characteristics of different types of work and the relationship between these characteristics and the prevalence of NIHL were analyzed.

RESULTS

The noise waveform shape, with a specific noise kurtosis, was unique to each type of work. Approximately 27.92% of manufacturing workers suffered from HFNIHL, with a mean NIPTS346 of 24.16 ± 14.13 dB HL. The Spearman correlation analysis showed that the kurtosis value was significantly correlated with the difference of peak SPL minus its LAeq.8h across different types of work (p < 0.01). For a kurtosis-adjusted CNE, the linear regression equation between HFNIHL% and CNE for complex noise almost overlapped with Gaussian noise. Binary logistic regression analysis showed that LAeq.8h, kurtosis, and exposure duration were the key factors influencing HFNIHL% (p < 0.01). The notching extent in NIPTS at 4 kHz became deeper with the increase in LAeq.8h and kurtosis. HFNIHL% increased most rapidly during the first 10 years of exposure. HFNIHL% with β ≥ 10 was significantly higher than that with β < 10 (p < 0.05), and it increased with increasing kurtosis across different CNE or LAeq.8h levels. When LAeq.8h was 80 to 85 dB(A), the HFNIHL% at β ≥ 100 was significantly higher than that at 10 ≤ β < 100 or β < 10 (p < 0.05 and p < 0.01, respectively).

CONCLUSIONS

In the evaluation of hearing loss caused by complex noise, not only noise energy but also the temporal structure of noise must be considered. Kurtosis of noise is an indirect metric that is sensitive to the presence of impulsive components in complex noise exposure, and thus, it could be useful for quantifying the risk for NIHL. It is necessary to re-evaluate the safety of permissible exposure limit of 85 dB(A) as noise with a high kurtosis value can aggravate or accelerate early NIHL.

Association of self-reported noise exposure and audiograms processed with algorithms proposed to quantify noise-induced hearing loss

OBJECTIVE

The objective of this study was to assess the association of self-reported noise exposure and audiograms processed with ten algorithms proposed to quantify noise-induced hearing loss using receiver operating characteristic (ROC) curves.

DESIGN

Participants were placed into groups based on self-reported noise exposure. Self-reported noise exposure served as a predictor for noise-induced hearing loss (NIHL). Audiograms were analysed with ten algorithms: The Guidelines, Brewster's Rules, two versions of military Noise-induced Hearing Loss, the Bulge Depth, the age-adjusted 8 kHz threshold and four versions of a new algorithm called the Adjusted Notch Depth (AND). The area under the ROC curves were calculated for each algorithm.

STUDY SAMPLE

Data were collected from three cycles of the National Health and Nutrition Examination Survey.

RESULTS

Only one version the AND significantly identified those with self-reported noise exposure with an area under the curve of 0.562.

CONCLUSIONS

The association between the AND and self-reported noise exposure was marginally better than the previous algorithms in identifying those with self-reported noise exposure. These findings do not support using puretone thresholds for identifying those with NIHL in a cross-sectional research study without stratifying the participants. More research is needed to determine how the AND can be applied to stratified designs.

Systematic Review of Interventions to Prevent Occupational Noise-Induced Hearing Loss - A Follow-up

PURPOSE

To conduct a systematic review of the effectiveness of interventions to prevent occupational hearing loss, following up on the findings of the most recent version of Cochrane systematic review on the same topic.

RESEARCH STRATEGY

Searches were carried out in PubMed, Web of Science and Scopus databases.

SELECTION CRITERIA

The following interventions were considered: engineering/administrative controls; hearing protection devices (HPD); and audiological monitoring.

DATA ANALYSIS

For bias risk analysis, each study was assessed according to randomization, allocation, blinding, outcomes, other sources of bias.

RESULTS

475 references were obtained. Of these, 17 studies met the inclusion criteria: one randomized, one interrupted time series, and 15 before and after studies. Most studies were conducted in industries; three in military and/or shooting training environments; one in an orchestra, and one in construction. Most studies showed a high risk of bias. Six studies found a reduction in short-term exposure to noise through engineering/administrative controls; one found a positive impact due to changes in legislation; five studies have found positive effects of HPD in reducing exposure to noise and of educational trainings in the use of HPD; lastly, two studies found a reduction in noise levels and an increase in the using of HPD due to the implementation of hearing conservation programs.

CONCLUSÃO

Todos os estudos analisados concluíram que as intervenções utilizadas resultaram em efeitos positivos sobre a audição e/ou sobre a exposição ao ruído. Em relação aos efeitos de longo termo, a grande maioria dos estudos limitou-se a avaliar efeitos imediatos ou de curto termo, reforçando que estudos incluindo follow-up de longo termo devem ser desenvolvidos.

Modeling individual noise-induced hearing loss risk with proxy measurements of external-ear amplification

Significant variability in noise-induced hearing loss (NIHL) susceptibility suggests there are factors beyond sound level and duration of exposure that contribute to individual susceptibility. External-ear amplification (EEA) from external-ear structures varies significantly due to ear size and shape, potentially influencing NIHL susceptibility. This study tested the hypothesis that EEA can be predicted using non-technical proxy measurements including pinna height (cm), body height (m), and earcanal volume (cm³). 158 participants (4-78 years) completed otoscopy, tympanometry, pinna measurements, body height measurements, and two EEA measurements: (1) total real-ear unaided gain (REUG) of the open ear and (2) real-ear to coupler difference (RECD), representing unaided gain from the earcanal. Participants' individual noise doses were compared in hypothetical exposures. REUG ranged from 5 to 19 dBA and was correlated with pinna height. High-REUG participants were estimated to accrue noise doses at least 5 times higher than low-REUG participants. RECD ranged from 7 to 24 dBA and was correlated with earcanal volume and body height. The results support the hypothesis that EEA measurement could significantly improve estimation of an individual's position along the NIHL risk spectrum. Non-technical proxy measurements of EEA (pinna height, body height, earcanal volume) were statistically significant but yielded high variability in individual EEA prediction.

Occupational Hearing Loss Associated With Non-Gaussian Noise: A Systematic Review and Meta-analysis

OBJECTIVES

Epidemiological characteristics of occupational noise-induced hearing loss (NIHL) associated with non-Gaussian noise are still unclear and have been rarely reported in the literature.

METHODS

The relationships between non-Gaussian noise exposure and occupational NIHL were analyzed based on the published papers. Systematic review and meta-analysis of epidemiological studies were performed.

RESULTS

Of 78 epidemiological studies (47,814 workers) selected, there were seven cohort studies and 71 cross-sectional studies. The incidence of high-frequency NIHL (HFNIHL) and speech-frequency NIHL (SFNIHL) in the seven cohort studies was 10.9 and 2.9%, respectively. In 71 cross-sectional studies, the prevalence of HFNIHL and SFNIHL was 34.2 and 18.9%, respectively. The average hearing threshold level at the high frequencies was 42.1 ± 17.4 dB HL. Workers exposed to non-Gaussian noise had a higher risk of developing HFNIHL than those not exposed to noise (overall-weighted odds ratio [OR] = 4.46) or those exposed to Gaussian noise (overall-weighted OR = 2.20). The Chi-square trend test demonstrated that the prevalence of HFNIHL was positively correlated with age, cumulative noise exposure, and exposure duration (p < 0.001).

CONCLUSIONS

Workers exposed to non-Gaussian noise suffered from greater NIHL than those exposed to Gaussian noise or not exposed to noise. Age, exposure duration, noise level, and noise temporal structure were the main risk factors for occupational NIHL. The A-weighted equivalent continuous sound pressure level (LAeq) is not a sufficient measurement metric for quantifying non-Gaussian noise exposure, and a combination of kurtosis and noise energy metrics (e.g., LAeq) should be used. It is necessary to reduce the exposure of non-Gaussian noise to protect the hearing health of workers.

Loud Music and Leisure Noise Is a Common Cause of Chronic Hearing Loss, Tinnitus and Hyperacusis

High sound levels capable of permanently damaging the ear are experienced not only in factories and war zones but in concert halls, nightclubs, sports stadiums, and many other leisure environments. This review summarizes evidence that loud music and other forms of "leisure noise" are common causes of noise-induced hearing loss, tinnitus, and hyperacusis, even if audiometric thresholds initially remain within clinically normal limits. Given the huge global burden of preventable noise-induced hearing loss, noise limits should be adopted in a much broader range of settings, and education to promote hearing conservation should be a higher public health priority.

Effects of hearing protector devices on speech intelligibility: the importance of individualized assessment

Objectives. This study aimed to compare speech intelligibility in noise with and without hearing protection devices (HPDs). Methods. Fifty-one workers were distributed into three groups: noise-induced hearing loss group (NIHLG), normally hearing noise-exposed group (NG) and normally hearing non-exposed to noise group (CG). A free field system was used to emit monosyllables (65, 70 and 75 dB) and pink noise in different signal-to-noise ratios (SNRs) (0, -5, -10 and -15). Results. In situations with HPDs, all groups showed a decrease in the percentage of correct responses with an increase in noise level. The HPD had little effect on speech intelligibility in the NIHLG and NG. Considering the effect caused by the HPD on speech intelligibility, it was observed that the group with the greatest loss was the CG for SNRs of -5, -10 and -15. Conclusion. Although speech intelligibility is influenced by the hearing threshold, the noise level and SNR are crucial for good speech intelligibility, either with or without an HPD. It is highlighted that the NG had worse results when compared with the CG, which may indicate changes in the auditory pathway resulting from continuous noise exposure, even in the absence of changes in the audiometric thresholds.

Acoustic Safety Management at the Locksmith’s Workplace Mechanic-Repairman to Replace the Filter Material in the Technological Process of Obtaining of Apatite Concentrate

In this work, measures are being developed to reduce the noise level at the workplace of a mechanic-repairman to replace filter cloth. Based on the results of production control and a thorough assessment of working conditions, the source of noise was determined to be the VDN-17 fan. The analysis of Russian and foreign studies in the field of the negative impact of noise on the human health and methods of dealing with industrial noise has been carried out. As a result, a technical method of reducing negative impact of noise was selected and the acoustic efficiency of the muffler for the VDN-17 fan was calculated.

Validity of hearTest Smartphone-Based Audiometry for Hearing Screening in Workers Exposed to Noise

PURPOSE

 This article investigates the validity of a smartphone-based audiometry for hearing screening to identify hearing loss in workers exposed to noise.

RESEARCH DESIGN

 This is a validation study comparing hearing screening with the hearTest to conventional audiometry. The study population included all workers who attended the Brazilian Social Service of Industry to undergo periodic examinations. Sensitivity, specificity, the Youden index, and positive (PPV) and negative predictive values (NPV) for hearing screening obtained by the hearTest were estimated according to three definitions of hearing loss: any threshold greater than 25 dB hearing level (HL), the mean auditory thresholds for 0.5, 1, 2, and 4 kHz greater than 25 dB HL, and the mean thresholds for 3, 4, and 6 kHz greater than 25 dB HL. Note that 95% confidence intervals were calculated for all measurements.

RESULTS

 A total of 232 workers participated in the study. Hearing screening with the hearTest presented good sensitivity (93.8%), specificity (83.9%), and Youden index (77.7%) values, a NPV (97.2%), and a low PPV (69.0%) for the identification of hearing loss defined as any auditory threshold greater than 25 dB HL. For the other definitions of hearing loss, we observed high specificity, PPV and NPV, as well as low sensitivity and Youden index.

CONCLUSION

 The hearTest is an accurate hearing screening tool to identify hearing loss in workers exposed to noise, including those with noise-induced hearing loss, although it does not replace conventional audiometry.

Hearing Difficulties and Tinnitus in Construction, Agricultural, Music, and Finance Industries: Contributions of Demographic, Health, and Lifestyle Factors

High levels of occupational noise exposure increase the risk of hearing difficulties and tinnitus. However, differences in demographic, health, and lifestyle factors could also contribute to high levels of hearing difficulties and tinnitus in some industries. Data from a subsample (n = 22,936) of the U.K. Biobank were analyzed to determine to what extent differences in levels of hearing difficulties and tinnitus in high-risk industries (construction, agricultural, and music) compared with low-risk industries (finance) could be attributable to demographic, health, and lifestyle factors, rather than occupational noise exposure. Hearing difficulties were identified using a digits-in-noise speech recognition test. Tinnitus was identified based on self-report. Logistic regression analyses showed that occupational noise exposure partially accounted for higher levels of hearing difficulties in the agricultural industry compared with finance, and occupational noise exposure, older age, low socioeconomic status, and non-White ethnic background partially accounted for higher levels of hearing difficulties in the construction industry. However, the factors assessed in the model did not fully account for the increased likelihood of hearing difficulties in high-risk industries, suggesting that there are additional unknown factors which impact on hearing or that there was insufficient measurement of factors included in the model. The levels of tinnitus were greatest for music and construction industries compared with finance, and these differences were accounted for by occupational and music noise exposure, as well as older age. These findings emphasize the need to promote hearing conservation in occupational and music settings, with a particular focus on high-risk demographic subgroups.

Occupational noise-induced hearing loss in China: a systematic review and meta-analysis

OBJECTIVE

Most of the Chinese occupational population are becoming at risk of noise-induced hearing loss (NIHL). However, there is a limited number of literature reviews on occupational NIHL in China. This study aimed to analyse the prevalence and characteristics of occupational NIHL in the Chinese population using data from relevant studies.

DESIGN

Systematic review and meta-analysis.

METHODS

From December 2019 to February 2020, we searched the literature through databases, including Web of Science, PubMed, MEDLINE, Scopus, the China National Knowledge Internet, Chinese Sci-Tech Journal Database (weip.com), WanFang Database and China United Library Database, for studies on NIHL in China published in 1993-2019 and analysed the correlation between NIHL and occupational exposure to noise, including exposure to complex noise and coexposure to noise and chemicals.

RESULTS

A total of 71 865 workers aged 33.5±8.7 years were occupationally exposed to 98.6±7.2 dB(A) (A-weighted decibels) noise for a duration of 9.9±8.4 years in the transportation, mining and typical manufacturing industries. The prevalence of occupational NIHL in China was 21.3%, of which 30.2% was related to high-frequency NIHL (HFNIHL), 9.0% to speech-frequency NIHL and 5.8% to noise-induced deafness. Among manufacturing workers, complex noise contributed to greater HFNIHL than Gaussian noise (overall weighted OR (OR)=1.95). Coexposure to noise and chemicals such as organic solvents, welding fumes, carbon monoxide and hydrogen sulfide led to greater HFNIHL than noise exposure alone (overall weighted OR=2.36). Male workers were more likely to experience HFNIHL than female workers (overall weighted OR=2.26). Age, noise level and exposure duration were also risk factors for HFNIHL (overall weighted OR=1.35, 5.63 and 1.75, respectively).

CONCLUSIONS

The high prevalence of occupational NIHL in China was related to the wide distribution of noise in different industries as well as high-level and long-term noise exposure. The prevalence was further aggravated by exposure to complex noise or coexposure to noise and specific chemicals. Additional efforts are needed to reduce occupational noise exposure in China.

Socio-economic disparity in the global burden of occupational noise-induced hearing loss: an analysis for 2017 and the trend since 1990

OBJECTIVES

To evaluate socio-economic disparity in the global burden of occupational noise-induced hearing loss (ONIHL) using disability-adjusted life-years (DALYs).

METHODS

The numbers of DALYs due to ONIHL, age-standardised DALY rates and national human development index (HDI) data from 1990 to 2017 were collected. The relationship between the age-standardised DALY rates and the 2017 HDI was analysed. A concentration index (CI) and a relative index of inequality (RII) were calculated to evaluate the trend in socio-economic disparity in the burden of ONIHL for the period 1990-2017.

RESULTS

From 1990 to 2017, the global DALYs due to ONIHL increased from 3.3 to 6.0 million, with the highest growth occurring in low-income countries (110.7%). Age-standardised DALY rates due to ONIHL were negatively associated with the HDI (β = -0.733, p<0.001), and these rates were significantly higher in countries with a lower HDI. From 1990 to 2017, the trend in between-country inequality was flat with little fluctuation, the CIs stayed near -0.17, and the RIIs remained near 0.35.

CONCLUSIONS

Over the past few decades, low-income countries have experienced the most rapid growth in DALYs worldwide. A widening socio-economic disparity has persisted in the global burden of ONIHL, with a higher burden in lower socio-economic countries. These data suggest that more prevention programmes and healthcare services should be provided for developing countries.

Diagnosis and quantification of military noise-induced hearing loss

The diagnosis and quantification of noise-induced hearing loss (NIHL) in a medico-legal context are usually based on the pattern of hearing loss that is typically associated with long-term exposure to steady broadband noises, such as occur in noisy factories. Evidence is reviewed showing that this pattern is not typical for hearing loss produced by intense impulsive sounds of the type that military personnel are exposed to. The audiometric characteristics of noise-exposed military personnel are reviewed. A set of audiograms from a sample of 58 hearing-impaired noise-exposed military veterans was analyzed and used to develop methods for the diagnosis and quantification of military NIHL. Three requirements are specified for diagnosing military NIHL. Quantification of any loss is done by comparison with audiometric thresholds for non-noise exposed individuals, as specified in ISO7029 [International Organization for Standardization, 2017].

Prevalence of hearing loss among noise-exposed workers within the services sector, 2006-2015

OBJECTIVE

The purpose of this study is to estimate the prevalence of hearing loss among noise-exposed U.S. workers within the Services sector.

METHODS

Audiograms for 1.9 million workers (158,436 within Services) from 2006 to 2015 were examined. Prevalence and adjusted risk for hearing loss as compared with a reference industry were estimated for the Services sector/sub-sectors, and all industries combined.

RESULTS

The prevalence of hearing loss within Services was 17 compared to 16% for all industries combined. However, many sub-sectors greatly exceeded the overall prevalence (10-33% higher) and/or had adjusted risks significantly higher than the reference industry. Workers in Administration of Urban Planning and Community and Rural Development had the highest prevalence (50%), and workers in Solid Waste Combustors and Incinerators had more than double the risk, the highest of any sub-sector. Some sub-sectors traditionally viewed as 'low-risk' also had high prevalences and risks.

CONCLUSIONS

Large numbers of workers within Services have an elevated risk of hearing loss and need immediate hearing conservation efforts. Additional research and surveillance are needed for sub-sectors for which there is low awareness of hearing hazards or a lack of hearing data.

Occupational noise and age: A longitudinal study of hearing sensitivity as a function of noise exposure and age in South African gold mine workers

BACKGROUND

A relationship exists between occupational noise exposure and age, which remains poorly understood.

OBJECTIVES

The aim of this study was to establish the relationship between hearing loss and age over time.

METHOD

Audiological data from 2583 mine workers in South Africa were utilised. Data were received from a non-noise exposed group (NNEG) (n = 951) and a noise exposed group (NEG) (≥85 dBA) (n = 1632). Data comprised a low-frequency average (LFA512) (average of audiological thresholds for 0.5 kHz, 1 kHz and 2 kHz) and high-frequency average (HFA346) (average of audiological thresholds for 3 kHz, 4 kHz and 6 kHz). Data were compared by using mixed-effects regression analysis.

RESULTS

Base threshold values were higher for the NEG than for the NNEG across frequencies. All year-to-year increases in mean hearing thresholds were statistically significant (p 0.01). When correcting for age, increases in mean hearing thresholds were higher for the NEG than for the NNEG for HFA346 (3.5 dB vs. 2.9 dB decline over a 4-year period) but similar for LFA512 (0.6 dB vs. 0.7 dB decline). Uncorrected for age, increases in mean hearing thresholds were higher than when age was corrected for.

CONCLUSION

Age and occupational noise exposure influence hearing thresholds over time. The continued increase in hearing thresholds of the NEG above that of the NNEG can be related to ineffective noise management programmes and/or the fact that early noise exposure leads to a higher burden of hearing loss over time - even after noise exposure had stopped.

Hearing prevention program: how speech-language pathologists and audiologists work in the occupational health area

ABSTRACT Objective: to characterize speech-language pathologists/audiologists and their interventions in the occupational health area, regarding the Hearing Prevention Program (HPP). Methods: a cross-sectional, quantitative study with 74 speech-language pathologists/audiologists from several regions of Brazil, working in the areas of Occupational Health and Audiology. The participants answered a questionnaire on their professional and educational profile, as well as on their work related to the HCP components. For data analysis, statistical procedures were used (Chi-Square Test and the test of difference in proportions, at the significance level of 0.05 - 5%), in relation to the variables of gender, age, job position, time since their graduation and academic training in occupational safety and health. Results: the speech-language pathologists/audiologists, mostly women, who reported performing the HPP, were older than 30 years, had specific postgraduate courses, but still had doubts about the Program implementation, they worked for companies with over 1,000 employees, disregarding their employment status, performing interventions, such as: hearing management and guidance on the correct use of ear protectors. Conclusion: a high number of speech-language pathologists in the Occupational Health area have not developed a complete hearing conservation program to this date.

The chinchilla animal model for hearing science and noise-induced hearing loss

The chinchilla animal model for noise-induced hearing loss has an extensive history spanning more than 50 years. Many behavioral, anatomical, and physiological characteristics of the chinchilla make it a valuable animal model for hearing science. These include similarities with human hearing frequency and intensity sensitivity, the ability to be trained behaviorally with acoustic stimuli relevant to human hearing, a docile nature that allows many physiological measures to be made in an awake state, physiological robustness that allows for data to be collected from all levels of the auditory system, and the ability to model various types of conductive and sensorineural hearing losses that mimic pathologies observed in humans. Given these attributes, chinchillas have been used repeatedly to study anatomical, physiological, and behavioral effects of continuous and impulse noise exposures that produce either temporary or permanent threshold shifts. Based on the mechanistic insights from noise-exposure studies, chinchillas have also been used in pre-clinical drug studies for the prevention and rescue of noise-induced hearing loss. This review paper highlights the role of the chinchilla model in hearing science, its important contributions, and its advantages and limitations.

Occupational noise exposure: A review of its effects, epidemiology, and impact with recommendations for reducing its burden

Exposure to hazardous noise is one of the most common occupational risks, both in the U.S. and worldwide. Repeated overexposure to noise at or above 85 dBA can cause permanent hearing loss, tinnitus, and difficulty understanding speech in noise. It is also associated with cardiovascular disease, depression, balance problems, and lower income. About 22 million U.S. workers are currently exposed to hazardous occupational noise. Approximately 33% of working-age adults with a history of occupational noise exposure have audiometric evidence of noise-induced hearing damage, and 16% of noise-exposed workers have material hearing impairment. While the Mining, Construction, and Manufacturing sectors typically have the highest prevalence of noise exposure and hearing loss, there are noise-exposed workers in every sector and every sector has workers with hearing loss. Noise-induced hearing loss is preventable. Increased understanding of the biological processes underlying noise damage may lead to protective pharmacologic or genetic therapies. For now, an integrated public health approach that (1) emphasizes noise control over reliance on hearing protection, (2) illustrates the full impact of hearing loss on quality of life, and (3) challenges the cultural acceptance of loud noise can substantially reduce the impact of noise on worker health.

Noise-induced hearing loss and its prevention: Integration of data from animal models and human clinical trials

Animal models have been used to gain insight into the risk of noise-induced hearing loss (NIHL) and its potential prevention using investigational new drug agents. A number of compounds have yielded benefit in pre-clinical (animal) models. However, the acute traumatic injury models commonly used in pre-clinical testing are fundamentally different from the chronic and repeated exposures experienced by many human populations. Diverse populations that are potentially at risk and could be considered for enrollment in clinical studies include service members, workers exposed to occupational noise, musicians and other performing artists, and children and young adults exposed to non-occupational (including recreational) noise. Both animal models and clinical populations were discussed in this special issue, followed by discussion of individual variation in vulnerability to NIHL. In this final contribution, study design considerations for NIHL otoprotection in pre-clinical and clinical testing are integrated and broadly discussed with evidence-based guidance offered where possible, drawing on the contributions to this special issue as well as other existing literature. The overarching goals of this final paper are to (1) review and summarize key information across contributions and (2) synthesize information to facilitate successful translation of otoprotective drugs from animal models into human application.

Prevalence of hearing loss among noise-exposed workers within the Mining and Oil and Gas Extraction sectors, 2006-2015

BACKGROUND

The purpose of this study was to estimate the prevalence of hearing loss (HL) among noise-exposed US workers within the Mining, and Oil and Gas Extraction (OGE) sectors.

METHODS

Audiograms of 1.9 million workers across all industries (including 9389 in Mining and 1076 in OGE) from 2006 to 2015 were examined. Prevalence and adjusted risk as compared to a reference industry (Couriers and Messengers) were estimated for all industries combined and the Mining and OGE sectors and subsectors.

RESULTS

The prevalences of HL in Mining and OGE were 24% and 14%, respectively, compared with 16% for all industries combined. Many Mining and one OGE subsector exceeded these prevalences and most had an adjusted risk (prevalence ratio) significantly greater than the reference industry. Some subsectors, particularly in OGE, could not be examined due to low sample size. The prevalences in Construction Sand and Gravel Mining and Natural Gas Liquid Extraction were 36% and 28%, respectively. Workers within Support Activities for Coal Mining had double the risk of HL than workers in the reference industry.

CONCLUSIONS

The many subsectors identified with high prevalences and/or worker risks for HL well above risks in the reference industry need critical attention to conserve worker hearing and maintain worker quality of life. Administrative and engineering controls can reduce worker hazardous noise exposures. Noise and ototoxic chemical exposure information is needed for many subsectors, as is audiometric testing results for OGE workers. Additional research is also needed to further characterize exposures and improve hearing conservation measures.

Risk assessment of recordable occupational hearing loss in the mining industry

Objective: To evaluate the hearing loss risk in different sectors and subunits in the mining industry and to identify associated occupations, in an attempt to locate gaps between hearing conservation efforts and hearing loss risks.Design: Descriptive statistics and frequency tables were generated by commodity types, subunit operations, and/or occupations. Temporal trends of the incidences of hearing loss were reported by commodity types.Study Sample: The MSHA Accident/Injury/Illness and MSHA Address/Employment databases from 2000 to 2014 were used.Results: Incidence rate of OHL was reported highest in the coal sector compared to other commodity types. Those members of the workforce that entered the mining industry after the year 2000 accounted for 6.5% and 19.0% of the total hearing loss records for coal and non-coal, respectively. High-risk occupations found in all three commodity sectors (coal; stone, sand, and gravel; and metal/non-metal) were electrician/helper/wireman, mechanic/repairman/helper, bulldozer/tractor operator, and truck driver.Conclusion: Hearing loss risks were not uniform across mining sectors, subunit operations, and occupations. In addition to the continuous efforts of implementing engineering controls to reduce machinery sound level exposure for operators, a multi-level approach may benefit those occupations with a more dynamic exposure profile - e.g., labour/utilityman/bullgang, electrician/helper/wireman, and mechanic/repairman/helper.