Hearing Protection Research Articles

A Study on the Hearing Protection Effect of Noise-Filtering Earplugs for Dentists

The aim of this study is to evaluate the effect of noise-filtering earplugs on the hearing ability of dentists wearing them during noise-induced dental procedures. Pure tone audiometry and distortion product otoacoustic emission (DPOAE) tests were conducted at the initial visit and 1 year later to evaluate the hearing ability of the participants. As a result of the study, the pure tone average of the group wearing earplugs decreased significantly compared to the group not wearing earplugs, indicating an improvement in hearing. However, the signal-to-noise ratio of the DPOAE tests did not show a significant difference. These findings suggest that noise-filtering earplugs may have some effectiveness in preventing hearing loss. However, since the 1-year observation period may not be adequate to identify changes in hearing, a follow-up study with an extended follow-up period is necessary.

Evaluating the effects of audiovisual delays on speech understanding with hearables

A key consideration in the development of real-time speech processing algorithms is latency between when speech is first captured and when the processed speech is transmitted. Much of the previous work informing the acceptability of processing latency has focused on the thresholds at which delays are detectable or annoying. This study aimed to explore the effects of delays on responding to a task necessitating speech understanding. Sentence-length audiovisual speech stimuli were modified such that the audio stream was delayed relative to the visual stream as well as to an attenuated copy of the audio stream by 10 and 400 ms, respectively. These stimuli were presented in conjunction with a pictorial referent-choice task to 50 normal-hearing participants. Participants responded slower to the task when the audio stream was delayed by 400 ms relative to the video stream. With an additional attenuated copy of the audio stream synchronized with the video stream, reaction time decreased, but this effect was limited to when the target word appeared near the onset of the sentence, highlighting the complexity of delay perception in the context of continuous speech. Implications for determining permissible processing delays for digital electronic hearing protection devices are discussed.

Intratympanic Dexamethasone Role in Hearing Protection in Cancer Patients.

Introduction The study aims to determine the role of intratympanic dexamethasone (ITD) on the hearing profile of patients with head and neck cancer post-chemoradiotherapy. Study design This study employs a prospective case-control design. Subjects and methods In total 834 patients were evaluated for eligibility. Seven hundred and elevenwere excluded because they didn't meet the inclusion criteria. A hundred cases out of 123 were diagnosed with head and neck cancer for which the treatment protocol included cisplatin concurrent to radiotherapy recruited. Before each cisplatin treatment session, ITD was injected into one ear (experimental ear) while the other ear of the same patient served as the control. Pure-tone audiometry (PTA) and distortion product otoacoustic emissions (DPOAE) test results of the baseline and follow-up examinations in the sixth and 12th weeks were compared within and between the study and control ears. Results For pure tone thresholds, significant hearing threshold change was noticed at 8 kHz in the experimental group at six weeks and at ≥ 6 kHz in the control group. At 12 weeks, high frequencies were significantly affected at ≥ 4 kHz in the control group. When the baseline was compared across the groups in the 12th week, for otoacoustic emissions, high frequencies showed a loss in the control group more compared to the experimental side (Wilcoxon signed-rank test). Conclusion ITD functions less effectively at higher frequencies because the basal turn of the cochlea is more susceptible to cisplatin ototoxicity. ITD might have potential in the reduction of cisplatin-induced hearing loss.

Design of a Mini Rice Harvester for Rural and Small Scale Rice Farmers in Tropical and Developing Countries

Food insecurity, price volatility and under-employment of rice farmers in Liberia are key drivers for the development of rice farming machines locally. This project work aims to design and fabricate a simple, low-cost, efficient mini rice harvester powered by a solar panel by translating learnt concepts and principles of engineering into a physical and workable rice harvester. A circular blade cutter, DC motor, DC battery and solar cells are the main components deployed on a rod-plate setup. The solar cell taps solar irradiance from the sun and, with the help of a charge controller, recharges a 12V, 35Amp.hour battery. The battery supplies DC current to a DC motor that drives a circular blade cutter during harvesting. The fabricated harvester fulfilled all design objectives and was justifiable on overall financial cost (USD 194.00), ease of use, and ease of reproduction. The performance of the harvester, in terms of smoothness of cut and completion of cut area, was found to be near 100%. However, the harvester field efficiency performance was found to be 30.75% with an aggregated efficiency of % and a payback period of only 71 hours of operation, equivalent to 60,696 sq.m of harvested rice farm. Incessant clogged cutter's surface and harvested stem removal delays, slowdowns as the operator makes turns, switch failures and re-fix delays during field tests are the primary causes of the low field efficiency. With an improved spacing between the blade cutter and the secondary guard, the performance of the harvester is expected to improve significantly. An average noise level of 88.8 decibels was detected during the harvester's operation; advisably, hearing protection earmuffs may be necessary to safely operate the mini harvester on the dailies for 6 hours. Notwithstanding that the effect of moisture content of the rice stalks, as an input parameter, was not considered in the development of the power requirement for the rice cutter, the harvester can be optimized with minimal effort for commercialization and adopted as a Made-In-Liberia invention.

Perforated Concave Earplug (pCEP): A Proof-of-Concept Earplug to Improve Sound Localization without Compromising Noise Attenuation.

Combat soldiers are currently faced with using a hearing-protection device (HPD) at the cost of adequately detecting critical signals impacting mission success. The current study tested the performance of the Perforated-Concave-Earplug (pCEP), a proof-of-concept passive HPD consisting of a concave bowl-like rigid structure attached to a commercial roll-down earplug, designed to improve sound localization with minimal compromising of noise attenuation. Primarily intended for combat/military training settings, our aim was an evaluation of localization of relevant sound sources (single/multiple gunfire, continuous noise, spoken word) compared to 3M™-Combat-Arms™4.1 earplugs in open-mode and 3M™-E-A-R™-Classic™ earplugs. Ninety normal-hearing participants, aged 20-35 years, were asked to localize stimuli delivered from monitors evenly distributed around them in no-HPD and with-HPD conditions. The results showed (1) localization abilities worsened using HPDs; (2) the spoken word was localized less accurately than other stimuli; (3) mean root mean square errors (RMSEs) were largest for stimuli emanating from rear monitors; and (4) localization abilities corresponded to HPD attenuation levels (largest attenuation and mean RMSE: 3M™-E-A-R™-Classic™; smallest attenuation and mean RMSE: 3M™-Combat-Arms™4.1; pCEP was mid-range on both). These findings suggest that the pCEP may benefit in military settings by providing improved sound localization relative to 3M™ E-A-R™-Classic™ and higher attenuation relative to 3M™-Combat Arms™-4.1, recommending its use in noisy environments.

Parameters influencing auditory fatigue among professionals working in the amplified music sector: noise exposure and individual factors

Objective Hearing disorders are common among music professionals, as they are frequently exposed to sound levels exceeding 100 dB(A). By assessing auditory fatigue, situations that are deleterious for hearing could be identified, allowing the deployment of preventive measures before permanent impairment occurs. However, little is known about the factors contributing to auditory fatigue. The objective is to determine the exposure parameters most influencing auditory fatigue during occupational exposure to amplified music. Design Auditory fatigue was defined as variations of both pure tone auditory (ΔPTA) and efferent reflex thresholds (ΔER) during the workday. Noise exposure was monitored and information on the volunteers was gathered using a questionnaire. Study sample The population consisted of 43 adult volunteers exposed to amplified music (sound, light or stage technicians, security agents, barmen) and 24 unexposed administrative agents. Results ΔPTA and ΔER were positively correlated with the energy of noise exposure and its stability over time, i.e a steady noise tends to create more auditory fatigue. Conclusion In addition to a global decrease of music levels and a systematic use of hearing protection, our results advocate for the provision of quiet periods within noise exposures as they reduce auditory fatigue accumulation and long-term risks for hearing.

Epidemiology of Occupational Injuries and Workplace Assessment in Turnery Industries at an Industrial District, Eastern Cairo, Egypt

Background Occupational injury could be fatal or non-fatal with lost work time. Turneries are workplaces in which multiple simultaneous health hazards occur and the most common hazards are mechanical hazards. Objective To measure the frequency and types of injuries among a sample of turnery workers, to identify risk factors of occupational injuries among them, and to describe the environmental conditions at some of these turneries as a part of occupational safety prospective. Methods A cross-sectional survey was conducted on 75 workers in three Industrial areas in Eastern Cairo El-herafeen, Madinat Al-salam and El-Abour. Data were collected using a structured interview questionnaire with both close and open-ended questions, and an observational environmental checklists were filled by the researcher. Results Seventy-five turnery workers were interviewed, (76%) of them reporting injury during the last 12 months. About (46.7%) of operators believing that their work is extremely dangerous. The most significant determinants for occupational injuries (p value < 0.05) were lack of safety training, non-use of personal protective devices and work hazard perception. In environmental assessment, all work stations had non-covered traditional machines, only 2 work stations out of 10 assessed had natural ventilation with open windows; not any of the work stations had regular noise survey neither did any of the workers use hearing protection equipment even though it was available in 2 work stations; only 4 work stations had floors free from protruding nails, splinters, holes and loose boards, goggles were available in 4 stations while gloves and rubber boots were available in 6 stations. Conclusion Most of workers in small scale work stations specialized in turnery industry had occupational injury during the last 12 months. Most of the observed workstations did not comply with advised safety checklist.

DESCRIPTION OF NOISE IN THE COMPRESSOR AND GENERATOR AREA AT PT PERTAMINA EP ASSET 3 TAMBUN FIELD – BEKASI

PT Pertamina EP Asset 3 Tambun Field is a state-owned company engaged in Production Exploration, in the process this company has tools that must pay attention to the noise level, namely Compressors and Gensets. Compressors and generators are very influential on hearing loss in workers, therefore efforts to prevent hearing loss must be carried out. The objectives to be known are to know the noise conservation program, Standard Operating Procedures (SOP) in implementing noise conservation, and Implementation of Noise Conservation in Compressor and Genset Areas. This research method uses direct observation, interviews and literature studies. The results show that the Hearing Conservation Program has 7 (seven) components, namely: noise exposure survey, noise control, worker training, personal protective equipment, audiometric examination, recording and reporting, program assessment. The procedure used refers to the Individual Work Procedure (TKI) for Noise Measurement. The implementation of the Noise Measurement Program is carried out by the contractor once every 1 (one) year or every time there is a process change or a new tool. The Hearing Conservation Program must continue to make continuous improvements. It should be noted in monitoring workers in the Genset and Compressor area so that workers always use hearing protection equipment.

Cochlear implant surgery facilitates intracochlear distribution of perioperative systemic steroids

Background Systemically administered steroids are widely utilised for hearing preservation therapies. More recently, steroids have been administered to achieve hearing protection after cochlear implant surgery. Currently there is a lack of understanding as to which administration route offers most therapeutic efficacy, local or systemic administration. Paramount to this are observations in animal studies that systemic administration following implantation offers hearing protection and reduced cochlear fibrosis, despite observations that perilymphatic levels are up to 10-fold higher after local administration in non-implanted cochleae. Aims/Objectives This paper explores the impact that cochlear implantation and associated acute inflammation has on steroid distribution and uptake following systemic administration of dexamethasone. Material and Methods Eight guinea pigs received systemic dexamethasone 60 min prior to cochlear implantation. Implanted and contralateral non-implanted cochlea were harvested for tissue immunohistochemistry and detection of dexamethasone. Results Cochleostomy with scala tympani implantation resulted in a significant increase in cochlear dexamethasone signal. This was most notable at the organ of Corti, stria vascularis, and blood product in the scala tympani. Conclusions and Significance This study demonstrates that the inner ear distribution of systemically administered steroids is enhanced following surgery for cochlear implantation and provides rationale for systemic perioperative steroids in hearing preservation surgery.

Healthcare Professionals and Noise-Generating Tools: Challenging Assumptions about Hearing Loss Risk.

Hearing loss is a significant global health concern, affecting billions of people and leading to various physical, mental, and social consequences. This paper focuses on the risk of noise-induced hearing loss (NIHL) among specific healthcare professionals, especially ear surgeons, orthopaedic surgeons, dentists, and dental hygienists, who frequently use noisy instruments in their professions. While studies on these professionals' noise exposure levels are limited, certain conditions and factors could pose a risk to their hearing. Measures such as engineering and administrative controls, regular audiometric testing, and the use of hearing protection devices are crucial in preventing NIHL. Early detection and intervention are also vital to mitigate further damage. This paper proposes the results of a modified screening protocol, including questionnaires, audiometry, and additional diagnostic tests to identify and address potential hearing disorders. Specific healthcare professionals should remain aware of the risks, prioritize hearing protection, and undergo regular monitoring to safeguard their long-term auditory well-being.

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.

Experimental evaluation of earplug behavior in front of high-level impulse noise using laser Doppler vibrometer.

Hearing protection devices facing high-level impulse noises provide an attenuation, generally, between 20 and 40 dB. One reason for this limitation is the direct interactions between the protection device and the impulse waves. In the case of earplugs, direct transmissions through the earplug occur. These direct transmissions combine with the already well-studied indirect transmissions arising from wave propagation in the external ear's tissues (skin, cartilage, and bone). To evaluate the transmission induced directly by the earplug, an experimental protocol using a laser Doppler vibrometer was developed. Thus, the earplug's outer lateral face (OLF) displacements and acoustic pressure at the eardrum were measured simultaneously. Two earplugs (polyurethane foam and acrylonitrile butadiene styrene) inserted in an acoustic test fixture were stimulated with impulses ranging from 137 to 180 dB-peak. A slight earplug OLF movement in the ear canal varying from 1 μm to 0.1 mm could be observed, which is likely related to ear canal longitudinal compression. The earplug's OLF displacement and acoustic pressure variation at the eardrum strongly depended on the earplug type. These direct transmissions and underlying consequences considerably alter the protection efficiency.

Noise Exposure and Job Stress – a Structural Equation Model in Textile Industries

Noise exposure is one of the most important physical agents in the workplace which can induce job stress in several ways. The aim of this study was to model the interactions between independent and mediating variables and job stress using structural equation modeling. In this study, Weinstein’s noise sensitivity scale, noise annoyance questionnaire, Health and Safety Executive (HSE) job stress questionnaire and job satisfaction scale were used. To assess worker’s noise exposure, the 8-hours equivalent continuous A-weighted sound pressure level (LAeq;8 h), was measured based on ISO 9612 (2009). To achieve the aims of study, the structural equation model was run using R software 3.4.1 and Cytoscape software 3.6.0. Based on the results, while there was a direct positive correlation of noise exposure on total job stress, there were also indirect positive effects through job satisfaction and noise sensitivity as mediator variables. Using hearing protective devices negatively affected total job stress through a direct pathway and an indirect pathway when job satisfaction was a mediator variable. Regarding the total effect of noise exposure and using hearing protection devices on job stress subscales, it can be concluded that noise exposure and using hearing protection devices had greatest effect on colleagues support and demand, respectively. It can be concluded that noise exposure and lack of hearing protective devices have a significant positive effect on job stress among workers of a textile industry. In addition to the direct effect, this factor can induce job stress through noise sensitivity, job satisfaction and noise annoyance. Therefore, measures which can decrease any of the mentioned factors, also can alleviate job stress.

Estimate of the Percent Reduction of the Workers Hearing Loss by Doing a Training Intervention Based on BASNEF Pattern

If we want to provide the efficient training intervention to increase the duration of using hearing protection devices (HPDs) by workers, we need a tool that can estimate the person’s hearing threshold taking into account noise exposure level, age, and work history, and compare them with audiometry to find out the percent reduction of workers hearing loss. First, the workers noise exposure level was determined according to ISO 9612, then 4000 Hz audiometry was done to find age and work history. On basis of ISO 1999 the hearing threshold was estimated and if the hearing protection device was not used continuously and correctly, the hearing protection device's actual performance was reduced adjusted with person’s audiometry. After training intervention, the estimate was done again and was compared with the adjusted audiometry. According to ISO1999 standard estimation results, the percent reduction of the workers hearing loss level was 6.48 dB in intervention group. This level remained unchanged in control group. The mean score of hearing threshold estimation (standard ISO 1999) was statistically more significant than mean score of hearing threshold (p-value < 0.001). The results show not significant change in control group due to lack of changing of noise exposure level. In regards to the results of hearing threshold estimation based on ISO1999 and comparing with workers audiometry, it can be seen that BASNEF training intervention increases the duration of using the HPDs and it could be effective in reducing hearing threshold related to noise.

Assessment of Role of Job Components and Individual Parameters on the Raised Blood Pressure in a Noisy Industry

The present study aimed to determine the role of job components and individual parameters on the raised blood pressure among male workers of textile industry who were exposed to continuous high noise level. Information of all eligible subjects including demographic and individual characteristics, medical history and job characteristics were obtained by direct interview and referring to the medical records. All blood pressure measurements were done using mercury sphygmomanometer in the morning before work. The 8-hours equivalent A-weighted sound pressure level, the level of blood cholesterol and triglyceride, and noise annoyance was determined for each worker. As the result of weighted regression in path analysis (direct effect), only the work shift did not have a significant effect on blood pressure among the studied variables. It can be seen that variables including the level of triglyceride, cholesterol, and noise exposure have the most direct effects on blood pressure. The results of total effects showed that variables, including using the hearing protection device, age, work experience and visibility of sound source, did not have a significant effect on blood pressure. The results of this study indicate that occupational noise exposure alone and combined with other job components and individual parameters is associated with raised blood pressure. However, noise exposure was probably a stronger stressor for increased blood pressure.

Hierarchical unit cell employing a nonlinear energy sink for passive, low-pass amplitude filtering of acoustic waves

In this letter we present a hierarchical unit cell incorporating a nonlinear energy sink (NES) that functions as a low-pass amplitude filter. The hierarchical unit cell is composed of an outer and inner mass coupled by essentially nonlinear springs. Other than its nonlinear coupling to the outer mass, the inner mass is otherwise unconstrained and thus acts as an NES. Using numerical simulations, we show that the nonlinear unit cell passively filters incident waves as a function of their amplitude. The resonator is inactive at low amplitudes, permitting waves to pass. At high amplitudes, the NES activates and its resonant behavior reflects incident waves. Consequently, the unit cell effectively operates as an amplitude limiter for specific signal frequency and amplitude ranges. Notably, the passing of low-amplitude incident energy while bypassing the nonlinearity results in very little distortion in transmitted signals. We analytically investigate this behavior further using a harmonic balance method. The analysis supports the transmission filtering behavior as well as the activation of the nonlinear energy sink. Lastly, we design and construct the nonlinear unit cell and perform tests using incident and transmitted waveguides composed of monatomic chains. Both the nonlinear unit cell and monatomic chains are assembled using steel masses and additively-manufactured springs. We test the fabricated filter using low and high amplitude signals and observe amplitude filtering at various excitation frequencies that document strong agreement with numerical simulations and the analytical model. The ability to passively reflect high amplitude waves, and transmit low amplitude waves with minimal distortion, may inspire new devices for hearing protection, or for isolating and protecting sensitive equipment and instruments.

Noise levels at traffic intersections and awareness of noise pollution among traffic policemen and automobile drivers

Introduction: Noise pollution is an important health hazard in modern times and traffic policemen and automobile drivers are exposed to unregulated vehicular noise. This study aims to estimate the exposure levels from traffic noise for traffic policemen and automobile drivers and assess their awareness regarding noise pollution and the use of noise prevention measures. Methods: An analytical cross-sectional study was carried out comprising the exposed and the control group with 121 people in each group. Sound level estimation was carried out across 20 traffic intersections in the city at various times to assess the noise levels. All the participants were administered a pretested questionnaire to assess their awareness regarding noise pollution and as well as the use of noise prevention strategies. The chi-square test was used to estimate the difference between the two groups. P &lt;0.05 was considered statistically significant. Results: The noise levels at traffic intersections are above the permitted and acceptable limits. The mean ±SD of sound levels at traffic points range from 76.7±5.8 dB to 83.4±6.3 dB across various traffic intersections. The mean noise level at the traffic intersection was in the high-risk category (81-86dB) in 25% of traffic points while 75% of traffic points had noise levels in the moderate risk (76 - 81dB) category. 88% of the exposed group and 95% of the control group considered noise to be a form of pollution even though they were not aware of all the harmful effects. In practice, only 34% of study participants used some form of hearing protection measures, even though the majority were aware of the need to do so. Conclusion: The noise levels at traffic intersections are high. This is coupled with a lack of adequate use of hearing protective devices which can be detrimental to the inner ear. Frequent awareness programs are necessary to educate the occupationally exposed personnel on proper noise prevention strategies. At the same, time it is necessary to take decisive measures to curb the ever-increasing menace of occupational noise exposure.

The development and evaluation of an online hearing loss prevention program

Recent studies underline the need for research on approaches to encouraging healthy listening habits. This study aims to develop and evaluate an online hearing loss prevention program; and examine its influence on the participants’ use of hearing protection, hearing loss prevention knowledge, attitude towards noise, and program useability and adherence.The study was conducted in the county of Västra Götaland, Sweden, from March through October 2021. The program included four modules focused on hearing and hearing loss prevention and was accessible to the participants for four weeks. In total, 75 participants completed the program which was evaluated using the Youth Attitude to Noise Scale and four additional self-designed questionnaires. The questionnaires were deployed before and immediately after program completion.The findings indicate that the program may influence the participants’ attitudes toward noise and the use of hearing protection. The participants who completed the program perceived high useability and increased hearing loss prevention knowledge. This program is most needed to promote healthy hearing. Future studies should target specific groups with this program and evaluate its long-term effects.

SOCIAL EARPLUGS: A CASE STUDY ON INTEGRATING HUMAN AUGMENTATION IN HEARING PROTECTION

AbstractSocial augmentation refers to a human-computer integration technology that aims to enhance the user's social skills by supporting empathy, interaction and communication. This study investigated the implementation of social augmentation in hearing protection within the context of entertainment. Through a user-centred analysis, potential social augmentation functions for earplugs were conceived. Three innovative conceptual prototypes were then developed, each enriched with three social functions. Accordingly, each of these concepts should ensure that social skill is enhanced, facilitated or improved. To assess whether the concepts were successful, the social impact of the prototypes on the user and bystanders was evaluated and compared through questionnaires and focus groups using video footage. The results provided promising conclusions regarding the applied methodology and the potential for optimizing the iteration process of innovative human augmentation concepts.

The role of epigenetic modifications in sensory hair cell development, survival, and regulation.

The cochlea is the sensory organ in the periphery, and hair cells are its main sensory cells. The development and survival of hair cells are highly controlled processes. When cells face intracellular and environmental stimuli, epigenetic regulation controls the structure and function of the genome in response to different cell fates. During sensory hair cell development, different histone modifications can induce normal numbers of functional hair cells to generate. When individuals are exposed to environmental-related hair cell damage, epigenetic modification also plays a significant role in the regulation of hair cell fate. Since mammalian hair cells cannot regenerate, their loss can cause permanent sensorineural hearing loss. Many breakthroughs have been achieved in recent years in understanding the signaling pathways that determine hair cell regeneration, and it is fascinating to note that epigenetic regulation plays a significant role in hair cell regeneration. In this review, we discuss the role of epigenetics in inner ear cell development, survival and regeneration and the significant impact on hearing protection.