Hearing Protection Research Articles

Knowledge, attitude, and practices towards occupational noise among maintenance and administration workers of selected health facilities in Modimolle-Mookgopong Municipality, South Africa

ABSTRACT This study aimed to determine knowledge, attitude, and practices towards Noise-Induced Hearing Loss among maintenance and administration workers in selected health facilities in the Modimolle-Mookgopong Municipality. Non-probability convenient sampling was used to select 250 participants. Maintenance workers were populated within the age range of 26–35 years, being more than administrative personnel (COR 1.59, CI 0.8–3.16). Maintenance workers showed more knowledge of noise being an unwanted sound (COR 1.04, CI 0.29–3.73), an ear infection (COR 4.65, CI 1.48–14.58) and poor hearing of speech as a sign of hearing loss (AOR 0.25, CI 0.07–0.86). Thirty-four percent (34%) of maintenance workers believed that ear screening and assessments are important while 17.9% believed not to be important. Forty-eight percent (58%) of maintenance workers suggested that they could not use hearing protectors effectively without training while 13.7% suggested training is needed.

Investigation of stress in dogs during an MRI examination in response to hearing protection.

The aim of the present study was to investigate whether the wearing of hearing protection has a positive influence on stress levels during an MRI examination in dogs under anaesthesia. To this end, the stress hormones cortisol and arginine vasopressin (AVP) were measured in the saliva of patients wearing hearing protection during an MRI scan, as well as in the control group without hearing protection, before and after the scan. Pulse rate and noise level were also measured during the MRI. It was shown that salivary cortisol concentrations in dogs without hearing protection increased during the MRI examination, while those in the control group with hearing protection remained the same (p<0.05). The pulse range was greater in the control group without hearing protection, although not statistically significant. The maximum loudness during the MRI examination, measured at 200 cm from the gantry, was 87 dB(A). The results on the loudness during mri scan highlight that hearing protection should always be used to minimise hearing damage and possibly the stress level for dogs.

'Cultural Insights into Adults' Hearing Awareness and Personal Listening Device Habits: A Survey Study.

The aim of this study was to investigate adults' habits regarding personal listening devices (PLDs), associated factors such as tinnitus and hearing threshold shift, and their knowledge of safety measures, including the use of hearing protectors in noisy environments. A cross-sectional survey was designed and distributed online. Participants between the ages of 18 and 40 years were invited to complete the survey. The online survey was filled out by 274 individuals with an average age of 24.2 years (SD= 5.1 years). Based on age, the participants were grouped into young adults (18-23 years old, 151 participants) and adults (24-40 years old, 123 participants). The estimation of noise exposure was calculated based on self-reported responses of PLD use. Two categories emerged from this calculation: the participants with exposure lower than 80 dB were in the low exposure category (N: 196, 62.9 dB), while the participants with exposure higher than 80 dB were in the high exposure category (N: 78, 89.9 dB). Based on the age categories, most of the questionnaire answers were similar between the young adults and the adults, revealing similar habits in using their PLDs. However, the investigation based on exposure revealed differences, as the participants with high exposure levels were more likely to have hobbies that involved noise, and they were less likely to obtain hearing evaluations. Among the participants, 30% used their devices at the maximum volume level and on a daily basis. 33.5% reported experiencing worsening in hearing, 2.4% reported persistent tinnitus, 94.1% knew that hearing protectors were available but only 20.7% reported using hearing protectors. The study concludes that adults are at risk of hearing loss due to unsafe listening habits. A discrepancy between knowledge and practice is apparent and needs to be addressed in young adults by increasing awareness of hearing loss, hearing protection and annual hearing evaluation.

Training simulator for evaluating the effectiveness of personal noise protection equipment

A description of the laboratory simulator created at Murom Institute for the study of personal hearing protection equipmnent against acoustic noise is presented. General issues of assessing the effectiveness of such equipment are considered. It is shown that in the conditions of the educational process it is sufficient to use a laboratory simulator in the form of a human head manikin, equipped with the hearing organs’ simulators and microphones. The simulator includes a manikin head with a built-in microphone and the internal cavity filled with noise-absorbing material. The microphone is installed so that its center line coincides with the center line of the auricle auditory canal and its working surface (membrane location area) completely covers the hole cross-section in the holder, excluding the sound wave penetration into the area behind the microphone.The second microphone is placed in a special holder near the manikin and provides the noise sound pressure level monitoring in the area where the manikin is installed. Processing of the generated signals is carried out using a program for analyzing spaced acoustic noise based on LabView. Several pairs of electret microphone capsules for general use, type wm61, were selected for the simulator. The first measurements, showing the fundamental possibility of using the simulator in the educational process in the “Technosphere Safety” field of study, were carried out. It is shown that in the octave ranges, measurement accuracy can be ensured at a level of +3 ÷ -0.5 dB, which corresponds to the “Type 2” class in the ANSI system adopted in the USA.

Hearing loss during chemotherapy: prevalence, mechanisms, and protection.

Ototoxicity is an often-underestimated sequela for cancer patients undergoing chemotherapy, with an incidence rate exceeding 50%, affecting approximately 4 million individuals worldwide each year. Despite the nearly 2,000 publications on chemotherapy-related ototoxicity in the past decade, the understanding of its prevalence, mechanisms, and preventative or therapeutic measures remains ambiguous and subject to debate. To date, only one drug, sodium thiosulfate, has gained FDA approval for treating ototoxicity in chemotherapy. However, its utilization is restricted. This review aims to offer clinicians and researchers a comprehensive perspective by thoroughly and carefully reviewing available data and current evidence. Chemotherapy-induced ototoxicity is characterized by four primary symptoms: hearing loss, tinnitus, vertigo, and dizziness, originating from both auditory and vestibular systems. Hearing loss is the predominant symptom. Amongst over 700 chemotherapeutic agents documented in various databases, only seven are reported to induce hearing loss. While the molecular mechanisms of the hearing loss caused by the two platinum-based drugs are extensively explored, the pathways behind the action of the other five drugs are primarily speculative, rooted in their therapeutic properties and side effects. Cisplatin attracts the majority of attention among these drugs, encompassing around two-thirds of the literature regarding ototoxicity in chemotherapy. Cisplatin ototoxicity chiefly manifests through the loss of outer hair cells, possibly resulting from damages directly by cisplatin uptake or secondary effects on the stria vascularis. Both direct and indirect influences contribute to cisplatin ototoxicity, while it is still debated which path is dominant or where the primary target of cisplatin is located. Candidates for hearing protection against cisplatin ototoxicity are also discussed, with novel strategies and methods showing promise on the horizon.

Hearing Health at School: analysis of knowledge, behaviors and attitudes of Southern-Brazilian children and adolescents on noise.

to analyze the knowledge, behaviors, and attitudes of students on noise. We used an observational method study, in 32 Schools from Itajaí/Brazil, with a convenience sample, comprising 1,835 students, 45.7% females and 54.3% males, mean age of 11.53 ± 0.8 years, was conducted. The Portuguese version of Dangerous Decibels® questionnaire was applied. For the data analysis, descriptive and inferential statistics were used, significance level of 5%. A large part of the sample part of the sample had harmful hearing habits; 62.6% reported knowledge on the subject, but only 25.4% answered the questions on the theme correctly; 58.9% reported that they did not know how to protect hearing if necessary. Regarding sex and age: males have more hazardous hearing habits (p < 0.001) and tinnitus complaint (p<0.001) and females have more knowledge (p < 0.001) and the intent to wear hearing protection (p<0.001), greater intention to wear hearing protection among younger students (10 and 11 years old) (p < 0.001), and the older ones (12 to 16 years old) get more exposed to noise (p < 0.001), and there are more tinnitus complaints (p < 0.05) among them. A large part of the students in the study has hazardous noisy habits and scarce knowledge on the theme, with males and older subjects showing the worst attitudes and behaviors in face of the potential hearing risk caused by exposure to high noise levels.

Dabrafenib protects from cisplatin-induced hearing loss in a clinically relevant mouse model.

The widely used chemotherapy cisplatin causes permanent hearing loss in 40%-60% of patients with cancer. One drug, sodium thiosulfate, is approved by the FDA for use in pediatric patients with localized solid tumors for preventing cisplatin-induced hearing loss, but more drugs are desperately needed. Here, we tested dabrafenib, an FDA-approved BRAF kinase inhibitor and anticancer drug, in a clinically relevant multidose cisplatin mouse model. The protective effects of dabrafenib, given orally twice daily with cisplatin, were determined by functional hearing tests and cochlear outer hair cell counts. Toxicity of the drug cotreatment was evaluated, and levels of phosphorylated ERK were measured. A dabrafenib dose of 3 mg/kg BW, twice daily, in mice, was determined to be the minimum effective dose, and it is equivalent to one-tenth of the daily FDA-approved dose for human cancer treatment. The levels of hearing protection acquired, 20-25 dB at the 3 frequencies tested, in both female and male mice, persisted for 4 months after completion of treatments. Moreover, dabrafenib exhibited a good in vivo therapeutic index (> 25), protected hearing in 2 mouse strains, and diminished cisplatin-induced weight loss. This study demonstrates that dabrafenib is a promising candidate drug for protection from cisplatin-induced hearing loss.

A Survey of Knowledge and Attitude of College Students Toward Hearing Loss Prevention.

College students risk hearing loss due to loud sound exposure during leisure activities. Hearing loss prevention is possible by reducing the noise from the source, using hearing protection devices and increasing their knowledge and awareness on the effects of loud sound exposure. The study aims to assess the knowledge and attitude of college students regarding hearing loss and its prevention. A cross-sectional study design with a survey method was adopted. A total of 94 college students (mean age: 22 years; range: 18 to 26) who were pursuing an undergraduate and postgraduate degree (50 males and 44 females) formed the part of the study. The researcher administered a standardized self-reported Knowledge, Attitude and Behaviour questionnaire. The knowledge score in percentage and absolute scores for attitude were estimated. The mean knowledge score was 35.8 (SD ± 12.18; range: 12.5-75), and the attitude score was + 9.8 (SD ± 7.1; range: - 4 to + 30). Chi square test revealed no significant association between knowledge and attitude to sociodemographic characteristics. The study indicated that though college students lack knowledge, they had a positive attitude regarding hearing health and its protection. These findings implicate the importance of creating awareness and encouraging hearing protection strategies for college students.

Development and Human Factors Evaluation of a Portable Auditory Localization Training System.

To design and develop a Portable Auditory Localization Acclimation Training (PALAT) system capable of producing psychoacoustically accurate localization cues; evaluate the training effect against a proven full-scale, laboratory-grade system under three listening conditions; and determine if the PALAT system is sensitive to differences among electronic level-dependent hearing protection devices (HPDs). In-laboratory auditory localization training has demonstrated the ability to improve localization performance with the open (natural) ear, that is, unoccluded, and while wearing HPDs. The military requires a portable system capable of imparting similar training benefits as those demonstrated in laboratory experiments. In a full-factorial repeated measures design experiment, 12 audiometrically normal participants completed localization training and testing using an identical, optimized training protocol on two training systems under three listening conditions (open ear, TEP-100, and ComTac™ III). Statistical tests were performed on mean absolute accuracy score and front-back reversal errors. No statistical difference existed between the PALAT and laboratory-grade DRILCOM systems on two dependent localization accuracy measurements at all stages of training. In addition, the PALAT system detected the same localization performance differences among the three listening conditions. The PALAT system imparted similar training benefits as the DRILCOM system and was sensitive to HPD localization performance differences. The user-operable PALAT system and optimized training protocol can be employed by the military, law enforcement, and various industries, to improve auditory localization performance in conditions where auditory situation awareness is critical to safety.

Earplug fit-testing system applying pure-tone audiometer

As for the sound attenuation measurement method of hearing protectors, such as earplugs and earmuffs, the real-ear attenuation at threshold (REAT) method is established by some standards such as ISO, ANSI, AS, etc. As known, however, sound attenuation differences between workers wearing protectors in real occupational noise fields are not small due to personal size-fitness or wearing conditions of hearing protectors. Although personal hearing protector fit-testing systems have been developed and standardized in Western countries, the systems have not yet been standardized in Japan, so they are not applicable easily. The authors tried to apply the pure-tone audiometric system equipped with circumaural earphones used for a medical check-up to the fitting system for earplugs on this occasion, where the Japanese guidelines for preventing noise-induced impairments were revised for the first time in about 30 years. This paper describes the overview of the earplug fit-test system applying the audiometer and trial test results of sound attenuation ratings by the proposed system.

Overview of the acoustics and psychoacoustics of reverse alarms installed on moving vehicles

Audible alarms are often used on mobile equipment to alert nearby workers of safety risks, in particular with reversing vehicles. A prompt reaction to the alert is required but depends on many technical factors (e.g., mounting location on vehicle), acoustic factors (e.g., alarm emission level, sound propagation pattern behind the vehicle) and psychoacoustic factors (e.g., perceived urgency, ability to localize alarm, effect of hearing loss and hearing protection). These factors are not fully addressed in applicable regulations or standards. This paper presents an overview of the main results of a series of research studies carried out as a collaborative effort by the "Institut de recherche Robert-Sauvé en santé et sécurité du travail" in Montreal and the University of Ottawa in the past twelve years. A main objective was to compare the relative benefits of two types of alarm signals, the widely-used conventional tonal signal and the relatively recent, but emerging, broadband signal. Overall, results indicate that the broadband alarm presents some benefits such as more uniform acoustic propagation patterns, lower alarm reaction thresholds and better sound localization compared to the tonal alarm. The latter two advantages are emphasized when hearing protectors are worn.

Development of the ear insertion-type noise dosimeter with hearing protection

This study developed the ear insertion-type noise dosimeter with an earpiece. This dosimeter is composed of features two microphones, one located at the ear canal entrance, and the other positioned inside the ear canal. The dosimeter calculates LAeq and LApeak at one-second intervals. The device logs data from both the inside and outside microphones for up to 8 hours, and the recorded data can be conveniently accessed and displayed on a smartphone. The difference between the inside LAeq and the outside LAeq indicates the exposed level attenuated by the earpiece. The ear insertion-type noise dosimeter was evaluated in a free field by using an acoustic measurement manikin (KEMAR; GRAS Inc, Denmark). Results obtained in this study showed that the differences between the LAeq in the free field and that at the entrance of the ear canal were found to be slightly amplified by the pinna effect. Also, the LAeqs measured at the microphone that positioned inside the ear canal was consistently 3.2 dB lower on average than that recorded by KEMAR's microphone. These findings suggest that the LAeq on the eardrum can be estimated by using the LAeq measured by the inside microphone. Additionally, the sound attenuation value can be calculated by comparing the values obtained from the outside microphones with those from the inside microphones.

Enhanced finite-element model and acoustic test fixture to assess the objective occlusion effect induced by earplugs under bone-conducted stimulation

The occlusion effect refers to the increased perception, mainly at low frequencies, of bone-conducted sounds like physiological noises and one's own voice when one wears hearing protection devices. This phenomenon may lead to an acoustic discomfort and subsequently to less effective protection. It can be quantified by an objective indicator defined as the difference between the sound pressure level in the open and occluded earcanal. Several finite-element models based on truncated outer ears are available in the literature for predicting the objective occlusion effect but they suffer from several limitations mainly due to anatomical simplifications. In this paper, the occlusion effect of earplugs is assessed using an enhanced finite-element model and an augmented acoustic test fixture both based on the same real head geometry of a living participant. The finite-element head model is evaluated by comparing numerical results with various experimental data. The augmented acoustic test fixture is evaluated itself with respect to the participant. Using the finite-element model, the variability of the occlusion effect induced by the uncertainty on the stimulation position of the bone transducer, the position in the earcanal where the occlusion effect is assessed, and the uncertainty on the soft tissue Poisson's ratio is investigated.

Effective Engineering Noise Control Strategies with the Stochastic Noise Mapping Simulation Method: A Case Study in Palm Oil Mill

Excessive sound levels pose a substantial risk to the hearing health of industrial workers. This study introduces a stochastic noise mapping technique to propose effective engineering control methods for noise mitigation in the palm oil industry. A case study conducted in a Malaysian palm oil mill employed data to predict the noise mapping and assess personal noise exposure levels of workers. Results showed that 29.6% of the area fell within the high-risk zone, with 28.1% in the extremely high-risk zone. Personal noise monitoring revealed that many workers were exposed to excessive noise, with a maximum time-weighted average sound level of 99.2 dBA among the worker groups. Despite the provision of protective equipment by management, regular usage of hearing protectors during work shifts was lacking. To reduce noise levels, two engineering control methods were proposed: erecting noise barriers around high noise emission sources and limiting the maximum sound power to 110 dBA for dynamic noise sources. Implementing these controls resulted in a 10.9% decrease in the extremely high-risk zone and a 17.8% decrease in the high-risk zone. These findings hold significance as they can guide the implementation of noise monitoring practices and engineering noise control in the industry.

Attitudes towards hearing, hearing loss, and hearing protection in university students

Objective Young adults are at risk for hearing loss caused by exposure to loud music. Intervention at this stage provides opportunities to support lifelong hearing protection use. This study explores attitudes related to hearing, hearing loss, and hearing protection among university students. Design Qualitative interview design, supplemented by quantitative questionnaire data. Study sample 18 university students, aged 18–24 years. Results Students were uncertain about mechanisms of noise-induced hearing loss, did not feel vulnerable to permanent hearing damage from loud music, were unconvinced of hearing protection efficacy, and reported barriers to hearing protection use. Students emphasised the positive effects of loud music and reported an increased likelihood of using hearing protection were it used by peers. Music students appeared more aware of the negative effects of loud music exposure. Students reported conflicting attitudes regarding government regulation of hearing protection use. Conclusion Young adults require education about hearing protection from multiple, credible sources and need to understand the mechanisms behind noise-induced hearing loss in a way that makes it of high personal relevance.

Occupational Noise-Induced Hearing Loss in the City of Mosul: A Cross-sectional Study

Introduction: This study aimed to investigate the distribution of demographic characteristics and the prevalence of hearing loss among workers. Methods: The study sample consisted of 160 participants, and various demographic variables were examined. Data regarding age, gender, work experience, work hours, work nature, and work type were collected and analyzed. The degrees of hearing loss in the bilateral, left, and right ears were assessed, and the prevalence of hearing loss among different work types was examined. Audiograms were utilized to assess the degrees of hearing loss. The limitations of this study include a small sample size, and the cross-sectional design preventing causal relationships. Results: The majority of participants were male, and the age distribution showed a higher representation in the 30-49 years age range. The degrees of hearing loss were predominantly intermediate in the bilateral, left, and right ears. Military personnel had the highest prevalence of hearing loss, followed by builders, drivers, carpenters, and bakers. The logistic regression analysis indicated limited predictive power for age, diabetes mellitus (DM), years in the job, and years in the current job. However, the absence of formal training emerged as a significant factor associated with an increased likelihood of potential hearing loss. Conclusion: The findings highlight the importance of considering demographic characteristics and occupational factors in assessing the prevalence of hearing loss among workers. The results emphasize the need for occupational training programs and increased awareness of hearing protection measures in the workplace to mitigate the risk of hearing loss.

Mitigation ofHearing Damage With Liraglutide Treatment inChinchillas After Repeated Blast Exposures at Mild-TBI.

Although hearing protection devices (HPDs) have been widely used during training and combat, over one million veterans experience service-connected hearing loss. Hearing damage has been reported to be associated with blast-induced mild traumatic brain injury (mTBI) and there is a lack of understanding and treatment. Liraglutide is a glucagon-like peptide-1 receptor agonist and a potential treatment for TBI-induced memory deficits. This study aims to investigate the function of the liraglutide to prevent damage and facilitate hearing restoration in chinchillas exposed to multiple high-intensity, mTBI-level blasts. Chinchillas were divided into three treatment groups: blast control, pre-blast drug treatment, and post-blast drug treatment. On day 1, the chinchilla ears were protected by HPDs and exposed to three blasts with peak pressure levels of 15-25 psi. The auditory brainstem response (ABR), distortion product otoacoustic emission (DPOAE), and middle latency response (MLR) were recorded pre- and post-blast on day 1 and on days 4, 7, 14, and 28. Substantial acute damage was observed and progressively recovered in chinchillas after the blast exposures. The pre-blast treatment group exhibited the lowest elevation of the ABR threshold and reduction of the wave I amplitude on day 1 after blasts. The liraglutide treatment insignificantly facilitated the recovery of the DPOAE levels and ABR thresholds on days 14 and 28. The pre-blast treatment chinchillas showed reduced MLR amplitudes on days 4 and 7. This study indicated that the pre-blast liraglutide administration provided damage protection against blasts in addition to the HPDs. Current evidence suggests that the effect of liraglutide is more prominent in the early phase of the experiment.

Rate of chainsaw vibrations in laboratory conditions and level of chainsaw noise at different distances

The study is focused on the rate of vibrations and level of noise in the chainsaw model Stihl MS 362 which belongs in the group of the best-selling professional chainsaws in the world with a highly efficient anti-vibration system. Testing cuts to determine the rate of vibrations were made on the stems of two tree species: sessile oak (Quercus petraea (Matt.) Liebl.) and Norway spruce (Picea abies (L.) H. Karst.). The purpose of noise level measurement was to compare the influence of chainsaw noise on its operator and on the person occurring behind the zone of protection (5 and 10 metres) from the source of noise. Then a distance from the chainsaw was measured where the level of noise reached 80 dB. The measurements were performed according to ČSN EN ISO 22868:2021. At measuring the chainsaw vibrations, the rate of vibrations acting on both operator’s hands (front and rear grip) was examined. Vibrations were measured according to ČSN EN ISO 22867 (2012). It was found out that the rate of vibrations on the rear handle was in both cases of measurements higher than the rate of vibrations on the front handle. At the same time, a higher rate of vibrations was recorded in sessile oak. As to the level of noise, results of measurements indicated that at working with the chainsaw, hearing protectors have to be used at all three measured distances (close proximity, 5 m from the operator, 10 m from the operator) in order to reduce high noise level as the average noise level was higher than permissible in all measurements. The highest possible tolerable level of acoustic noise (80 dB) at which permanent damage of hearing does not happen was measured at a distance of 21 m from the working place of chainsaw operator. Keywords: chainsaw, Stihl MS 362, vibrations, noise, occupational hygiene, forestry

New Paradigm of Music Listening: Hearing Protection Perceptions and Treatment Decision-Making Among Music Venue Attendees.

Investigate the prevalence of hearing protection (HP) use and behavioral motivations and barriers among adults attending music venues. Cross-sectional online survey study. Noise exposure levels at popular social music venues often exceed national guidelines. Surveys were distributed on online music communities. Respondents (n = 2352) were asked about demographics, HP use at music venues, knowledge about noise exposure impact, and perceptions of HP use. Data were characterized through descriptive statistics. Multivariable regression analysis explored differences in knowledge and perception between HP users and nonusers. In this cohort (mean age 29 ± 7 years, 61% male), HP users were significantly more aware of the impact of music venues on hearing (P < .01), believed their hearing ability had decreased after attending music venues (P < 0.01), and believed HP could protect from hearing loss (P < .01) than non-HP users. HP nonusers most frequently cited never considering HP (14.45%) and apathy about it affecting music quality (12.71%). Common sources of HP information were recommended by a friend/peer. Multivariable regression analysis accounting for demographics, medical history, and attendance characteristics found belief that HP use at music venues could protect from hearing loss (β = 0.64, 95% confidence interval [CI] = [0.49-0.78]) and HP use (β = 1.73, 95% CI = [1.47-1.98]) were significantly associated with increased subjective enjoyment while wearing HP. HP users and nonusers have significantly different perceptions of HP use and its impact. Our findings have implications for understanding motivations and barriers related to HP use and developing strategies to promote HP use at music venues.

Accounting for individual differences in the effects of hearing protectors on sound source localization

Modern hearing protection devices (HPDs) mitigate the risk of noise-induced hearing loss when used as intended, but negative auditory perceptual side-effects continue to limit usability in critical settings. Dozens of studies, including previous studies by our group, have shown that HPDs lead to significant errors in sound source localization, including large errors in source elevation perception and disorienting front-back confusions. Degradation of performance relative to open-ear listening arises due to peripheral disruptions of monaural and binaural acoustic cues for sound localization; for higher-attenuation devices, reduced audibility can also limit access to these cues, even if cues are relatively intact. A recent multi-site effort by our group leveraged manikin-based acoustic measurements of HPD-induced signal distortions to predict human localization performance during HPD use. Manikin-based acoustic metrics were positively correlated with behavioral performance across a large population of human listeners (n ≥ 120), enabling discrimination of localization impacts across HPDs, but significant individual variability was evident. Here we consider individual factors that may contribute to variability in HPD localization impact across wearers, including audiometric factors and auricular/acoustic factors. Correlational analyses of individualized predictors with localization performance provide new insight on factors that may differentially constrain – or facilitate – sound localization during HPD use.