[A study on the hearing protection and intervention effects of silicone earplug usage among manufacturing workers].

Objective: To assess the efficacy of silicone earplugs in protecting workers exposed to noise in a typical manufacturing environment, and to provide training interventions for workers who do not achieve the anticipated noise reduction levels, as well as examining the spectral characteristics of earplug attenuation. Methods: From June to August 2022, a total of 294 noise-exposed workers in two manufacturing enterprises equipped with the same type of earplug were studied by cluster sampling method, by conducting questionnaire surveys, collecting data, fitting tests, and providing trainings, the current noise exposure levels of workers in the industry as well as the perception about the earplug were understood. Additionally, the attenuation before and after intervention in workplace were measured, the spectral characteristics of noise reduction were were described and compared. Results: The percentage of workers with Personal Attenuation Rating (PAR) of 0 is 32.7% (96/294), and the baseline pass rates are all below 60%. There were no significant differences in pass rates based on gender, age, noise exposure, education level, or cognition of earplug effectiveness. After adjusting the way that earplugs are worn or changing the type of earplugs, all workers were able to meet their noise reduction requirements. The median PAR improvement for both companies is above 10 dB. The noise attenuation of the earplug vary with frequency, with lower attenuation at 4 000 Hz and higher attenuation at 8 000 Hz, showing some deviation from the nominal values. Conclusion: The difference between the actual sound attenuation value of earplugs and the nominal value is related to the noise frequency. When using silicone earplugs, attention should be paid to the spectral composition of the noise in the workplace.

Multifunctional redox modulator prevents blast-induced loss of cochlear and vestibular hair cells and auditory spiral ganglion neurons.

Blast wave exposure, a leading cause of hearing loss and balance dysfunction among military personnel, arises primarily from direct mechanical damage to the mechanosensory hair cells and supporting structures or indirectly through excessive oxidative stress. We previously reported that HK-2, an orally active, multifunctional redox modulator (MFRM), was highly effective in reducing both hearing loss and hair cells loss in rats exposed to a moderate intensity workday noise that likely damages the cochlea primarily from oxidative stress versus direct mechanical trauma. To determine if HK-2 could also protect cochlear and vestibular cells from damage caused primarily from direct blast-induced mechanical trauma versus oxidative stress, we exposed rats to six blasts of 186 dB peak SPL. The rats were divided into four groups: (B) blast alone, (BEP) blast plus earplugs, (BHK-2) blast plus HK-2 and (BEPHK-2) blast plus earplugs plus HK-2. HK-2 was orally administered at 50 mg/kg/d from 7-days before to 30-day after the blast exposure. Cochlear and vestibular tissues were harvested 60-d post-exposure and evaluated for loss of outer hair cells (OHC), inner hair cells (IHC), auditory nerve fibers (ANF), spiral ganglion neurons (SGN) and vestibular hair cells in the saccule, utricle and semicircular canals. In the untreated blast-exposed group (B), massive losses occurred to OHC, IHC, ANF, SGN and only the vestibular hair cells in the striola region of the saccule. In contrast, rats treated with HK-2 (BHK-2) sustained significantly less OHC (67%) and IHC (57%) loss compared to the B group. OHC and IHC losses were smallest in the BEPHK-2 group, but not significantly different from the BEP group indicating lack of protective synergy between EP and HK-2. There was no loss of ANF, SGN or saccular hair cells in the BHK-2, BEP and BEPHK-2 groups. Thus, HK-2 not only significantly reduced OHC and IHC damage, but completely prevented loss of ANF, SGN and saccule hair cells. The powerful protective effects of this oral MFRM make HK-2 an extremely promising candidate for human clinical trials.

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

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

Oxidative Stress Assessment of Noise Exposure in the Workers Using Hearing Protection in a Pressing Industry.

BACKGROUND AND OBJECTIVE: Exposure to noise by generation of free radicals causes oxidative stress in body. The aim of this study was the evaluation of oxidative stress in workers who have used hearing protection devices during working time. MATERIAL AND METHOD: Pressing workers (n=24) of a home appliance industry were studied using hearing protection devices to reduce noise exposure. Twenty two office staff (without exposure to noise) were considered as a control group. Two groups were matched for age, work experience and smoking. Exposure to noise was measured by dosimeter method at workstations. By obtaining 3 ml blood sample, Malondialdehyde levels, Thiol groups and total antioxidant capacity were evaluated in all subjects. RESULTS: Exposure to sound pressure level in pressing workers by considering the noise reduction factor of the earplug was observed in 77.65 dB with minimum 75.1 dB and Maximum 81.22 dB. Plasma thiol groups (0.076 (0.041-0.119) vs (0.110 (0.076-0.197), mmol/l P =0.0001) and total antioxidant capacity (361.33± 54.65 vs 414.14± 96.82, µmol/ml P = 0.026) in pressing workers significantly decreased than control group. Pearson correlation showed significant results between exposure to noise and oxidative stress parameters. CONCLUSION: Exposure to noise wave cause oxidative stress in different site of body. Oxidative stress is an intermediate way for different disease due to noise exposure. Reducing of noise exposure by earplug in pressing workers is not efficient protection for oxidative stress generation. Therefore, hearing protection devices are not a barrier to the harmful effects of noise in occupational exposure.

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.

Music to Define a Generation: Factors Associated With Hearing Protection Use at Music Venues.

OBJECTIVES: Excessive noise levels in music venues can negatively impact long-term hearing health. We investigated the prevalence, characteristics, and factors associated with hearing protection use among music event attendees. STUDY DESIGN: Cross-sectional cohort. METHODS: Adult participants (2,352) from online music forums completed a questionnaire assessing attendance at music events, hearing protection (HP) usage, type, and frequency, along with history of hearing-related symptoms and medical history. Primary outcome was defined as HP use at music venues. Data were characterized using descriptive statistics, paired t tests, and Pearson's chi-squared tests. Multivariable regression analysis elicited factors associated with any and regular HP use. RESULTS: Our 2,352 respondents were primarily male (61.3%) and on average 28.7 years old (SD = 7.0). Of the respondents, 60.6% reported using HP, and 33.2% reported regular use; high-fidelity earplugs were the most used HP type (57.5%). HP use was associated with significantly fewer reports of negative hearing-related symptoms. In a multivariable regression model, factors associated with less likelihood of HP use included being female (vs male, OR = 0.74, CI = [0.55-0.98]), less concern about effects on hearing (OR = 0.53, CI = [0.45-0.61]), and pop music event attendance (vs EDM, OR = 0.40, CI = [0.22-0.72]). Increased attendance frequency in the past year was associated with higher likelihood of regular HP use (OR = 1.07, CI = [1.04-1.09]). Decreased attendance duration was associated with decreased likelihood (OR = 0.09, CI = [0.03-0.33]). CONCLUSION: HP use prevalence was high, while frequent use remained low. HP use was significantly associated with reduced hearing-related symptoms. Demographic factors, otologic symp-tomology, and attendance-related characteristics were associated with HP use. These findings may guide interventions to increase adoption at music venues. LEVEL OF EVIDENCE: 4.

Face the (unamplified) music: Key findings for musicians.

Music is complex. There are risks to hearing health associated with playing due to excessive sound exposure. Face the Music is an on-going cross-sectional project to assess the risks to unamplified classical musicians. Key findings over the first fifteen years are presented based on the research undertaken with a leading conservatoire on more than 5000 classical music students. The work covers hearing health surveillance, education and awareness, sound exposure, and new technology. The future of the research programme is discussed along with opportunities in objective hearing health assessment and new acoustic solutions. A lot has changed in fifteen years, but the research was driven by a change in United Kingdom legislation. It is hoped that the research results can inform future regulation.

Hearing protection field attenuation estimation systems and associated training for reducing workers' exposure to noise.

BACKGROUND: Global Burden of Disease studies identify hearing loss as the third leading cause of years lived with a disability. Their estimates point to large societal and individual costs from unaddressed hearing difficulties. Workplace noise is an important modifiable risk factor; if addressed, it could significantly reduce the global burden of disease. In practice, providing hearing protection devices (HPDs) is the most common intervention to reduce noise exposure at work. However, lack of fit of HPDs, especially earplugs, can greatly limit their effectiveness. This may be the case for 40% of users. Testing the fit and providing instructions to improve noise attenuation might be effective. In the past two decades, hearing protection fit-test systems have been developed and evaluated in the field. They are called field attenuation estimation systems. They measure the noise attenuation obtained by individual workers using HPDs. If there is a lack of fit, instruction for better fit is provided, and may lead to better noise attenuation obtained by HPDs. OBJECTIVES: To assess: (1) the effects of field attenuation estimation systems and associated training on the noise attenuation obtained by HPDs compared to no instruction or to less instruction in workers exposed to noise; and (2) whether these interventions promote adherence to HPD use. SEARCH METHODS: We used CENTRAL, MEDLINE, five other databases, and two trial registers, together with reference checking, citation searching, and contact with study authors to identify studies. We imposed no language or date restrictions. The latest search date was February 2024. SELECTION CRITERIA: We included randomised controlled trials (RCTs), cluster-RCTs, controlled before-after studies (CBAs), and interrupted time-series studies (ITSs) exploring HPD fit testing in workers exposed to noise levels of more than 80 A-weighted decibels (or dBA) who use hearing protection devices. The unit 'dBA' reports on the use of a frequency-weighting filter to adjust sound measurement results to better reflect how human ears process sound. The outcome noise attenuation had to be measured either as a personal attenuation rating (PAR), PAR pass rate, or both. PAR pass rate is the percentage of workers who passed a pre-established level of sufficient attenuation from their HPDs, identified on the basis of their individual noise exposure. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed study eligibility, risk of bias, and extracted data. We categorised interventions as fit testing of HPDs with instructions at different levels (no instructions, simple instructions, and extensive instructions). MAIN RESULTS: We included three RCTs (756 participants). We did not find any studies that examined whether fit testing and training contributed to hearing protector use, nor any studies that examined whether age, gender, or HPD experience influenced attenuation. We would have included any adverse effects if mentioned by the trial authors, but none reported them. None of the included studies blinded participants; two studies blinded those who delivered the intervention. Effects of fit testing of HPDs with instructions (simple or extensive) versus fit testing of HPDs without instructions Testing the fit of foam and premoulded earplugs accompanied by simple instructions probably does not improve their noise attenuation in the short term after the test (1-month follow-up: mean difference (MD) 1.62 decibels (dB), 95% confidence interval (CI) -0.93 to 4.17; 1 study, 209 participants; 4-month follow-up: MD 0.40 dB, 95% CI -2.28 to 3.08; 1 study, 197 participants; both moderate-certainty evidence). The intervention probably does not improve noise attenuation in the long term (MD 0.15 dB, 95% CI -3.44 to 3.74; 1 study, 103 participants; moderate-certainty evidence). Fit testing of premoulded earplugs with extensive instructions on the fit of the earplugs may improve their noise attenuation at the immediate retest when compared to fit testing without instructions (MD 8.34 dB, 95% CI 7.32 to 9.36; 1 study, 100 participants; low-certainty evidence). Effects of fit testing of HPDs with extensive instructions versus fit testing of HPDs with simple instructions Fit testing of foam earplugs with extensive instructions probably improves their attenuation (MD 8.62 dB, 95% CI 6.31 to 10.93; 1 study, 321 participants; moderate-certainty evidence) and also the pass rate of sufficient attenuation (risk ratio (RR) 1.75, 95% CI 1.44 to 2.11; 1 study, 321 participants; moderate-certainty evidence) when compared to fit testing with simple instructions immediately after the test. This is significant because every 3 dB decrease in noise exposure level halves the sound energy entering the ear. No RCTs reported on the long-term effectiveness of the HPD fit testing with extensive instructions. AUTHORS' CONCLUSIONS: HPD fit testing accompanied by simple instructions probably does not improve noise attenuation from foam and premoulded earplugs. Testing the fit of foam and premoulded earplugs with extensive instructions probably improves attenuation and PAR pass rate immediately after the test. The effects of fit testing associated with training to improve attenuation may vary with types of HPDs and training methods. Better-designed trials with larger sample sizes are required to increase the certainty of the evidence.

Noise or sound management in the neonatal intensive care unit for preterm or very low birth weight infants.

BACKGROUND: Infants in the neonatal intensive care unit (NICU) are subjected to different types of stress, including sounds of high intensity. The sound levels in NICUs often exceed the maximum acceptable level recommended by the American Academy of Pediatrics, which is 45 decibels (dB). Hearing impairment is diagnosed in 2% to 10% of preterm infants compared to only 0.1% of the general paediatric population. Bringing sound levels under 45 dB can be achieved by lowering the sound levels in an entire unit; by treating the infant in a section of a NICU, in a 'private' room, or in incubators in which the sound levels are controlled; or by reducing sound levels at the individual level using earmuffs or earplugs. By lowering sound levels, the resulting stress can be diminished, thereby promoting growth and reducing adverse neonatal outcomes. This review is an update of one originally published in 2015 and first updated in 2020. OBJECTIVES: To determine the benefits and harms of sound reduction on the growth and long-term neurodevelopmental outcomes of neonates. SEARCH METHODS: We used standard, extensive Cochrane search methods. On 21 and 22 August 2023, a Cochrane Information Specialist searched CENTRAL, PubMed, Embase, two other databases, two trials registers, and grey literature via Google Scholar and conference abstracts from Pediatric Academic Societies. SELECTION CRITERIA: We included randomised controlled trials (RCTs) or quasi-RCTs in preterm infants (less than 32 weeks' postmenstrual age (PMA) or less than 1500 g birth weight) cared for in the resuscitation area, during transport, or once admitted to a NICU or stepdown unit. We specified three types of intervention: 1) intervention at the unit level (i.e. the entire neonatal department), 2) at the section or room level, or 3) at the individual level (e.g. hearing protection). DATA COLLECTION AND ANALYSIS: We used the standardised review methods of Cochrane Neonatal to assess the risk of bias in the studies. We used the risk ratio (RR) and risk difference (RD), with their 95% confidence intervals (CIs), for dichotomous data. We used the mean difference (MD) for continuous data. Our primary outcome was major neurodevelopmental disability. We used GRADE to assess the certainty of the evidence. MAIN RESULTS: We included one RCT, which enroled 34 newborn infants randomised to the use of silicone earplugs versus no earplugs for hearing protection. It was a single-centre study conducted at the University of Texas Medical School in Houston, Texas, USA. Earplugs were positioned at the time of randomisation and worn continuously until the infants were 35 weeks' postmenstrual age (PMA) or discharged (whichever came first). Newborns in the control group received standard care. The evidence is very uncertain about the effects of silicone earplugs on the following outcomes. • Cerebral palsy (RR 3.00, 95% CI 0.15 to 61.74)and Mental Developmental Index (MDI) (Bayley II) at 18 to 22 months' corrected age (MD 14.00, 95% CI 3.13 to 24.87); no other indicators of major neurodevelopmental disability were reported. • Normal auditory functioning at discharge (RR 1.65, 95% CI 0.93 to 2.94) • All-cause mortality during hospital stay (RR 2.07, 95% CI 0.64 to 6.70; RD 0.20, 95% CI -0.09 to 0.50) • Weight (kg) at 18 to 22 months' corrected age (MD 0.31, 95% CI -1.53 to 2.16) • Height (cm) at 18 to 22 months' corrected age (MD 2.70, 95% CI -3.13 to 8.53) • Days of assisted ventilation (MD -1.44, 95% CI -23.29 to 20.41) • Days of initial hospitalisation (MD 1.36, 95% CI -31.03 to 33.75) For all outcomes, we judged the certainty of evidence as very low. We identified one ongoing RCT that will compare the effects of reduced noise levels and cycled light on visual and neural development in preterm infants. AUTHORS' CONCLUSIONS: No studies evaluated interventions to reduce sound levels below 45 dB across the whole neonatal unit or in a room within it. We found only one study that evaluated the benefits of sound reduction in the neonatal intensive care unit for hearing protection in preterm infants. The study compared the use of silicone earplugs versus no earplugs in newborns of very low birth weight (less than 1500 g). Considering the very small sample size, imprecise results, and high risk of attrition bias, the evidence based on this research is very uncertain and no conclusions can be drawn. As there is a lack of evidence to inform healthcare or policy decisions, large, well designed, well conducted, and fully reported RCTs that analyse different aspects of noise reduction in NICUs are needed. They should report both short- and long-term outcomes.

Sources of noise exposure across Australian workplaces: cross-sectional analysis and modelling the impact of a targeted noise-source reduction initiative.

CONTEXT: Workplace noise regulations and guidance follow the hierarchy of control model that prioritizes eliminating or reducing noise at its source. OBJECTIVES: To determine the main sources of workplace noise exposure in the Australian working population and estimate the reduction of workers exposed over the noise limit (LAeq,8h > 85 dB) if noise levels of specific tools or equipment were reduced by 10 dB. METHODS: Information on the tools used and tasks performed during each participant's last working shift was collected from 4,977 workers via telephone survey. Using a predetermined database of task-based noise levels, partial noise exposures (Pa2h) were determined for each noisy activity performed by the workers and their daily noise exposure level (LAeq,8h) was estimated. Partial exposures were categorized into 15 tool/task groups and the tally, average, and sum (Pa2h) for each group were calculated. The impacts of 5 different scenarios that simulated a reduction of 10 dB in noise emissions for specific tool groups were modelled. RESULTS: Powered tools and equipment were responsible for 59.3% of all noise exposure (Pa2h); vehicles for 10.6%; mining, refineries, and plant equipment for 5.1%; and manufacturing and food processing for 4.2%. Modelling demonstrated that a 10 dBA noise-level reduction of all powered tools and equipment would lead to a 26.4% (95% confidence interval: 22.7% to 30.3%) reduction of workers with an LAeq,8h > 85 dB. This could represent over 350,000 Australian workers no longer exposed above the workplace limit daily. CONCLUSIONS: A universal reduction of 10 dB to power tools and equipment would substantially reduce the future burden of hearing loss, tinnitus, workplace injuries, and other health effects. Initiatives to reduce the noise emissions of specific powered tool groups are warranted.

Managing acoustic noise within MRI: A qualitative interview study among Swedish radiographers.

INTRODUCTION: Acoustic noise from magnetic resonance imaging (MRI) can cause hearing loss and needs to be mitigated to ensure the safety of patients and personnel. Capturing MR personnel's insights is crucial for guiding the development and future applications of noise-reduction technology. This study aimed to explore how MR radiographers manage acoustic noise in clinical MR settings. METHODS: Using a qualitative design, we conducted semi-structured individual interviews with fifteen MR radiographers from fifteen hospitals around Sweden. We focused on the clinical implications of participants' noise management, using an interpretive description approach. We also identified sociotechnical interactions between People, Environment, Tools, and Tasks (PETT) by adopting a Human Factors/Ergonomics framework. Interview data were analyzed inductively with thematic analysis (Braun and Clarke). RESULTS: The analysis generated three main themes regarding MR radiographers' noise management: (I) Navigating Occupational Noise: Risk Management and Adaptation; (II) Protecting the Patient and Serving the Exam, and (III) Establishing a Safe Healthcare Environment with Organizational Support. CONCLUSION: This study offers insights into radiographers' experiences of managing acoustic noise within MRI, and the associated challenges. Radiographers have adopted multiple strategies to protect patients and themselves from adverse noise-related effects. However, they require tools and support to manage this effectively, suggesting a need for organizations to adopt more proactive, holistic approaches to safety initiatives. IMPLICATIONS FOR PRACTICE: The radiographers stressed the importance of a soundproofed work environment to minimize occupational adverse health effects and preserve work performance. They acknowledge noise as a common contributor to patient distress and discomfort. Providing options like earplugs, headphones, mold putty, software-optimized "quiet" sequences, and patient information were important tools. Fostering a safety culture requires proactive safety efforts and support from colleagues and management.

The influencing factors of hearing protection device usage among noise-exposed workers in Guangdong Province: a structural equation modeling-based survey.

BACKGROUND: There are numerous complex barriers and facilitators to continuously wearing hearing protection devices (HPDs) for noise-exposed workers. Therefore, the present study aimed to investigate the relationship between HPD wearing behavior and hearing protection knowledge and attitude, HPD wearing comfort, and work-related factors. METHOD: A cross-sectional study was conducted with 524 noise-exposed workers in manufacturing enterprises in Guangdong Province, China. Data were collected on hearing protection knowledge and attitudes, HPD wearing comfort and behavior, and work-related factors through a questionnaire. Using structural equation modeling (SEM), we tested the association among the study variables. RESULTS: Among the total workers, 69.47% wore HPD continuously, and the attitudes of hearing protection (26.17 ± 2.958) and total HPD wearing comfort (60.13 ± 8.924) were satisfactory, while hearing protection knowledge (3.54 ± 1.552) was not enough. SEM revealed that hearing protection knowledge had direct effects on attitudes (ß = 0.333, p < 0.01) and HPD wearing behavior (ß = 0.239, p < 0.01), and the direct effect of total HPD wearing comfort on behavior was ß = 0.157 (p < 0.01). The direct effect also existed between work shifts and behavior (ß=-0.107, p < 0.05). Indirect relationships mainly existed between other work-related factors, hearing protection attitudes, and HPD wearing behavior through knowledge. Meanwhile, work operation had a direct and negative effect on attitudes (ß=-0.146, p < 0.05), and it can also indirectly and positively affect attitudes through knowledge (ß = 0.08, p < 0.05). CONCLUSION: The behavior of wearing HPD was influenced by hearing protection knowledge, comfort in wearing HPD, and work-related factors. The results showed that to improve the compliance of noise-exposed workers wearing HPD continuously when exposed to noise, the HPD wearing comfort and work-related factors must be taken into consideration. In addition, we evaluated HPD wearing comfort in physical and functional dimensions, and this study initially verified the availability of the questionnaire scale of HPD wearing comfort.

Effects of Occupational Noise Exposure on Hearing Loss: Regulatory Effect of Mediterranean Diet.

OBJECTIVE: To assess regulatory effect of Mediterranean diet for occupational noise exposure and hearing loss. Methods: This cross-sectional study included 4757 individuals. Weighted logistic regression model was adopted to explore the association of occupational noise exposure and Mediterranean diet with hearing loss, and regulatory effects of the Mediterranean diet for the relationship of occupational noise exposure and hearing loss. Results: Occupational noise exposure was associated with an increased odds of hearing loss. Under low adherence to the Mediterranean diet, the occupational noise exposure group was related to increased odds of hearing loss. Under high adherence to the Mediterranean diet, no significant difference was observed between occupational noise exposure and hearing loss, and adjusted effect size was reduced accordingly. Conclusion: Mediterranean diet may moderate this relationship of occupational noise exposure and hearing loss to some degree.

Quantification of suppressor effects on breech and action noise from AR-15 pattern firearms and its implications for the protection of human hearing.

Noise from firearms is well known to be harmful to human hearing. This problem has been addressed by various military units through the use of muzzle suppressors. However, as suppressor technology has advanced, shooters report hearing the mechanical action of gas-operated semi-automatic rifles (ArmaLite Rifle Model 15 style aka AR-15) as being louder than the suppressed muzzle noise. This study aims to evaluate if harmful noise is present in the shooter's ear, even when impulse noise emanating from the muzzle is suppressed. To characterize the impulse noise of the firearm action caused by the reciprocation of the bolt carrier group (BCG) and subsequent impact when it returns to battery (the forward locked position), the muzzle of a rifle was placed through a constructed plywood wall, and the noise of the action/breech was measured independently from the muzzle noise. This research finds that the impact of the BCG returning to battery (132 dBZ) has the potential to be harmful to the shooter's hearing even when the noise from the muzzle is effectively suppressed.

Noise-Induced Hearing Loss and Use of Hearing Protection Awareness among Medical Students in Saudi Arabia: Mixed Qualitative and Quantitative Study.

BACKGROUND: Noise-Induced Hearing Loss (NIHL) is a prevalent occupational hazard among healthcare professionals, including medical students. Despite its detrimental effects, the awareness and utilization of hearing protection measures among medical students in Saudi Arabia remain understudied. OBJECTIVE: Is to determine the level of awareness and understanding of NIHL among medical students in Saudi Arabia, as well as their knowledge and usage of hearing protection measures and to identify potential barriers and facilitators for hearing protection utilization. METHODS: A mixed-methods approach was employed, involving a questionnaire survey and semi-structured interviews. The survey collected data on demographics, knowledge of NIHL, and hearing protection practices among medical students. Subsequently, a semi-structured interview was conducted to obtain in-depth insights into the students' experiences, attitudes, and beliefs regarding NIHL and the use of hearing protection. RESULTS: The level about NIHL was 59.32%. Better access to information is associated with increased odds of awareness (odds ratio=3.07, p=0.012). Having relatives with hearing loss increases the odds of awareness (odds ratio =2.49, p=0.034). Individuals with hearing loss or impairment have higher odds of awareness (odds ratio =2.27, p=0.046). Ear Pain, temporary hearing loss, tinnitus, or ringing in the ear: These factors are not significantly associated with awareness of noise-induced hearing loss (p>0.05). Using hearing aids is strongly associated with increased odds of awareness (odds ratio =3.94, p=0.006).The quantitative analysis provided statistical information on the prevalence rates and factors influencing hearing protection usage, while the qualitative analysis uncover nuanced perspectives and experiences. CONCLUSION: This research will contribute to the understanding of NIHL and hearing protection practices among medical students in Saudi Arabia. Improving hearing protection awareness and practices among medical students can ultimately reduce the incidence of NIHL and promote a healthier work environment within the healthcare sector.

An acoustical environment survey of student music practice.

Chronic exposure to loud sound leads to noise-induced hearing loss. This is especially common in collegiate-level musicians. Existing methods for estimating exposure typically do not consider genre- or instrument-specific variability in soundscape/spectral characteristics. We measured sound exposure levels (SELs) across instruments, bands, and genres at a university music school. We found (1) considerable variability in SELs across instruments and bands, (2) that Jazz musicians are consistently exposed to the highest sound levels, and (3) that spectral features of music differ between instrument type and genre, and based on room size. These findings highlight the need for tailored guidelines that moderate the implementation of hearing conservation initiatives for collegiate musicians.

Noise-induced hearing loss and hearing protection: Attitudes at a South African coal mine.

BACKGROUND:  Negative attitudes and beliefs are major contributing factors to the rising numbers of noise-induced hearing loss (NIHL) cases in coal mines both locally and internationally. International literature confirms limited knowledge surrounding employees' attitudes and beliefs regarding NIHL and hearing protection devices (HPDs), hence the need for the study. OBJECTIVES:  To ascertain the attitudes and beliefs about NIHL and HPD use among employees at a large scale underground coal mine in Mpumalanga. METHOD:  A descriptive and exploratory cross-sectional study was conducted using a self-administered questionnaire, developed by the National Institute for Occupational Safety and Health (NIOSH) on Beliefs about Hearing Protection and Hearing Loss (BHPHL). Participants (n = 241) included employees from a coal mine in Mpumalanga, South Africa. RESULTS:  Out of 241 completed surveys, this study found that 84% were aware of when to replace earmuffs; 95% believed wearing HPDs could prevent hearing loss in noisy environments; 83% felt their hearing was impacted by loud noise. Additionally, 86% mentioned discomfort from earmuff pressure; 95% emphasised HPD importance; and 95% used HPDs around loud sounds. Moreover, 98% knew how to properly wear earplugs, while lower education levels were linked to higher susceptibility to NIHL. CONCLUSION:  The study identified positive attitudes towards NIHL and HPD use, but existing NIHL cases must be acknowledged. Organisations can use the findings to develop tailored hearing conservation programmes (HCP), including education, involving employees in protection decisions and promoting diligent HPD usage.Contribution: This study contributes to the limited literature on noise perceptions, NIHL, and HPD use in mining, emphasising the impact attitude has on HPD use and assessing the effect of miners NIHL knowledge on compliance. The findings, unique to coal mining, hold significance for enhancing hearing conservation and reducing NIHL.

A novel model of sensorineural hearing loss induced by repeated exposure to moderate noise in mice: the preventive effect of resveratrol.

Sensorineural hearing loss (SNHL) induced by noise has increased in recent years due to personal headphone use and noisy urban environments. The study shows a novel model of gradually progressive SNHL induced by repeated exposure to moderate noise (8-kHz octave band noise, 90-dB sound pressure level) for 1 hr exposure per day in BALB/cCr mice. The results showed that the repeated exposure led to gradually progressive SNHL, which was dependent on the number of exposures, and resulted in permanent hearing loss after 5 exposures. Repeated exposure to noise causes a loss of synapses between the inner hair cells and the peripheral terminals of the auditory nerve fibers. Additionally, there is a reduction in the expression levels of c-fos and Arc, both of which are indicators of cochlear nerve responses to noise exposure. Oral administration of resveratrol (RSV, 50 mg/kg/day) during the noise exposure period significantly prevented the noise exposure-induced synapse loss and SNHL. Furthermore, the study found that RSV treatment prevented the noise-induced increase in the gene expression levels of the proinflammatory cytokine interleukin-1ß in the cochlea. These results demonstrated the potential usefulness of RSV in preventing noise-induced SNHL in the animal model established as gradually progressive SNHL.

Strategies of Hearing Preservation With Military Personnel: A Scoping Review.

PURPOSE: The purpose of this study was to map the strategies used in hearing health education with military personnel during the Hearing Preservation Program (HPP). METHOD: This study is a scoping review, with electronic searches conducted in online databases and gray literature: Latin American and Caribbean Literature in Health Sciences, PubMed/Medline, Scopus, Web of Science, ASHAWire, Google Scholar, and ProQuest Dissertation & Theses. Only studies describing, analyzing, or evaluating the application of the HPP to active duty or training military personnel were included. RESULTS: A total of 3,478 references were retrieved, and 12 studies met the inclusion criteria. The strategies were classified into five categories: focus group aimed at exploring knowledge and perceptions regarding hearing health (five studies), training on the proper fitting of hearing protection devices (four studies), the utilization of audiovisual materials (seven studies), questionnaires administrated before and after educational intervention (five studies), and feedback survey concerning the implemented hearing health education (three studies). CONCLUSION: There are five strategies that aimed at assessing knowledge and attitudes, improving hearing health education, facilitating information access, and evaluating the applied actions. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.25219589.

[Study on the fit testing for the workers wearing hearing protection device in machinery manufacturing enterprises].

Objective: To investigate the occupational noise hazards in five machinery manufacturing enterprises, and to evaluate the individual noise reduction values and influencing factors of workers wearing hearing protection device (HPD) by individual fit testing. Methods: From November 2021 to January 2022, 5 machinery manufacturing enterprises in Bao'an District of Shenzhen were selected to conduct an occupational health survey to understand the noise exposure level of workers. The 3MTM E-A-RfitTM fitness test system was used to test the baseline individual sound attenuation value level (PAR) of the daily wear of the ear protecters for 485 workers in typical noise working positions. Workers whose PAR values could not meet the requirements of noise reduction at work were instructed to wear and repeated tests were conducted. PAR results of the workers before and after the intervention were collected and analyzed. Results: The noise workers who received the suitability test were mainly distributed in 24 types of work, the job noise exposure level was 80.2 dB (A) ~ 95.0 dB (A), and the job noise excess rate was 52.5% (138/263). The median baseline PAR [M (Q(1), Q(3)) ] for 485 workers was 6.0 (0.0, 14.0) dB. The baseline PAR of male workers, those with more than 15 years of working experience, those with more than 15 years of using ear guards, those who considered ear guards comfortable to wear, those with college degree or above, and those exposed to noise level 90 dB (A) were higher, and the difference was statistically significant (P<0.05). A total of 275 workers (56.7%) did not pass the baseline PAR test, and there was no statistically significant difference in the intervention rate of workers in different noise groups (P>0.05). PAR in subjects who did not pass baseline after intervention increased from 0.0 (0.0, 3.0) dB to 15.0 (12.0, 18.2) dB. Conclusion: The workplace noise hazard of machinery manufacturing enterprises is serious, and there is a great difference between the baseline PAR and the nominal value of the hearing guard worn by the noise exposed workers. The intervention measures can effectively improve the protective effect of wearing ear protectors.