Cochrane method for systematic review and meta-analysis of interventions to prevent occupational noise-induced hearing loss - abridged.

PURPOSE: Assess the effect of non-pharmaceutical interventions at work on noise exposure or occupational hearing loss compared to no or alternative interventions. RESEARCH STRATEGIES: Pubmed, Embase, Web of Science, OSHupdate, Cochrane Central and Cumulative Index to Nursing and Allied Health Literature (CINAHL) were searched. SELECTION CRITERIA: Randomized Controlled Trials (RCT), Controlled Before-After studies (CBA) and Interrupted Time-Series studies (ITS) evaluating engineering controls, administrative controls, personal hearing protection devices, and hearing surveillance were included. Case studies of engineering controls were collected. DATA ANALYSIS: Cochrane methods for systematic reviews, including meta-analysis, were followed. RESULTS: 29 studies were included. Stricter legislation can reduce noise levels by 4.5 dB(A) (very low-quality evidence). Engineering controls can immediately reduce noise (107 cases). Eleven RCTs and CBA studies (3725 participants) were evaluated through Hearing Protection Devices (HPDs). Training of earplug insertion reduces noise exposure at short term follow-up (moderate quality evidence). Earmuffs might perform better than earplugs in high noise levels but worse in low noise levels (very low-quality evidence). HPDs might reduce hearing loss at very long-term follow-up (very low-quality evidence). Seventeen studies (84028 participants) evaluated hearing loss prevention programs. Better use of HPDs might reduce hearing loss but other components not (very low-quality evidence). CONCLUSION: Hearing loss prevention and interventions modestly reduce noise exposure and hearing loss. Better quality studies and better implementation of noise control measures and HPDs is needed.

Occupational Hearing loss in Africa: An interdisciplinary view of the current status.

Noise-induced hearing loss is 100% preventable if the collaborative stakeholders in the prevention process are fully committed to the process and implement effective measures timely. Audiologists have within their scope of practice the prevention of hearing loss and this needs to be at the forefront of all advocacy campaigns to prevent occupational hearing loss (OHL). In a systematic review by Moroe, Khoza-Shangase, Kanji and Ntlhakana (2018), where literature into the exposure to occupational noise in developing countries suggested that the prevalence of occupational noise-induced hearing loss (ONIHL) is still high, significant gaps in locally relevant and responsive evidence were identified. There is also evidence that the mining industry is aware of this epidemic; however, the efforts to curb ONIHL are currently unsuccessful. These authors explored and documented current evidence reflecting trends in the management of ONIHL in the mining industry in Africa from 1994 to 2016 through the use of the Preferred Reporting Items for Systematic Reviews and Meta-Analysis. Findings from this systematic review indicated that there is a dearth of research on the management of ONIHL in Africa. The limited research on the management of ONIHL focuses on some aspects of the hearing conservation programme pillars and not on all the pillars as suggested by some scholars in the field. Furthermore, they found that published studies had small sample sizes, thereby minimising their generalisation. This systematic review's findings highlighted a need for more studies on the management of ONIHL in the mining sector, as evidence suggests that this condition in African countries is still on the rise; hence, there is the importance of this Special Issue, based on South Africa.

Risk versus benefit: Should not audiologists assess this in the context of occupational noise-induced hearing loss in the mining industry?

BACKGROUND: Hearing conservation programmes (HCPs) are an important aspect of occupational health efforts to prevent occupational noise-induced hearing loss (ONIHL). In low- and middle income (LAMI) countries, where the incidence of ONIHL is significant, it is important to deliberate on the risk or benefit of HCPs. OBJECTIVES: This article is an attempt at highlighting important strategic indicators as well as important variables that the occupational health and audiology community need to consider to plan efficacious HCPs within the South African mining context. METHOD: The current arguments are presented in the form of a viewpoint publication. RESULTS: Occupational audiology vigilance in the form of engagement with HCPs in the mining industry has been limited within the South African research and clinical communities. When occupational audiology occurs, it is conducted by mid-level workers and paraprofessionals; and it is non-systematic, non-comprehensive and non-strategic. This is compounded by the current, unclear externally enforced accountability by several bodies, including the mining industry regulating body, with silent and/or peripheral regulation by the Health Professions Council of South Africa and the Department of Health. The lack of involvement of audiologists in the risk or benefit evaluation of HCPs during their development and monitoring process, as well as their limited involvement in the development of policies and regulations concerning ear health and safety within this population are probable reasons for this. CONCLUSIONS: Increased functioning of the regulatory body towards making the employers accountable for the elimination of ONIHL, and a more central and prominent role for audiologists in HCPs, are strongly argued for.

Cochrane method for systematic review and meta-analysis of interventions to prevent occupational noise-induced hearing loss - abridged / Revisão sistemática e metanálise Cochrane de intervenções para prevenção de perda auditiva ocupacional induzida por ruído - abreviada

ABSTRACT Purpose Assess the effect of non-pharmaceutical interventions at work on noise exposure or occupational hearing loss compared to no or alternative interventions. Research strategies Pubmed, Embase, Web of Science, OSHupdate, Cochrane Central and Cumulative Index to Nursing and Allied Health Literature (CINAHL) were searched. Selection criteria Randomized Controlled Trials (RCT), Controlled Before-After studies (CBA) and Interrupted Time-Series studies (ITS) evaluating engineering controls, administrative controls, personal hearing protection devices, and hearing surveillance were included. Case studies of engineering controls were collected. Data analysis Cochrane methods for systematic reviews, including meta-analysis, were followed. Results 29 studies were included. Stricter legislation can reduce noise levels by 4.5 dB(A) (very low-quality evidence). Engineering controls can immediately reduce noise (107 cases). Eleven RCTs and CBA studies (3725 participants) were evaluated through Hearing Protection Devices (HPDs). Training of earplug insertion reduces noise exposure at short term follow-up (moderate quality evidence). Earmuffs might perform better than earplugs in high noise levels but worse in low noise levels (very low-quality evidence). HPDs might reduce hearing loss at very long-term follow-up (very low-quality evidence). Seventeen studies (84028 participants) evaluated hearing loss prevention programs. Better use of HPDs might reduce hearing loss but other components not (very low-quality evidence). Conclusion Hearing loss prevention and interventions modestly reduce noise exposure and hearing loss. Better quality studies and better implementation of noise control measures and HPDs is needed.

RESUMO Objetivo Avaliar o efeito de intervenções no trabalho sobre a exposição ao ruído ou a perda auditiva em comparação com ausência ou intervenções alternativas. Estratégia de pesquisa Buscas em Pubmed, Embase, Web of Science, OSHupdate, Cochrane Central e CINAHL. Critérios de seleção Incluídos ensaios clínicos randomizados (ECR), estudos controlados pré/pós-intervenção (ECPPI) e estudos de séries temporais interrompidas (SIT) avaliando controles de engenharia, administrativos, equipamentos de proteção auditiva (EPAs) e vigilância auditiva. Coletados estudos de caso de engenharia. Análise dos dados Cochrane para revisões sistemáticas, incluindo metanálise. Resultados Foram incluídos 29 estudos. Legislação mais rigorosa pode reduzir níveis de ruído em 4,5 dB(A) (evidência de qualidade muito baixa). Controles de engenharia podem reduzir imediatamente o ruído (107 casos). Onze ECR e ECPPI (3.725 participantes) avaliaram EPAs. Treinamento para inserção do EPA reduz a exposição ao ruído no acompanhamento de curto prazo (evidência de qualidade moderada). Protetores tipo concha podem ter desempenho melhor do que protetores de inserção em níveis altos de ruído, mas piores em níveis mais baixos (evidência de qualidade muito baixa). EPAs podem reduzir a perda auditiva no acompanhamento de muito longo prazo (evidência de qualidade muito baixa). Dezessete estudos (84.028 participantes) avaliaram programas de prevenção de perdas auditivas. Um melhor uso do EPA pode reduzir a perda auditiva, mas outros componentes não (evidência de qualidade muito baixa). Conclusão As intervenções para prevenção da perda auditiva reduzem modestamente a exposição ao ruído e a perda auditiva. Estudos de melhor qualidade e melhor implementação de medidas de controle de ruído e EPA são necessários.

Archivos y la labor invisible de sus directoras y directores: mejorando la capacitación investigadora en salud laboral / No disponible

No disponible

Evaluación del ruido y el confort acústico en la Biblioteca Agrícola Nacional. Lima, Perú / Noise and acoustic confort evaluation at the National Agriculture Library. Lima, Peru

La Biblioteca Agrícola Nacional (BAN) es la principal biblioteca de temática agropecuaria líder de Perú. Presta servicios en nueve salas de lectura, en dos edificaciones. Hasta la fecha, no se habían realizado evaluaciones de la percepción ni del confort acústico en salas de lectura como lo son las de una biblioteca. Dado que las bibliotecas son una de las principales herramientas para el desarrollo profesional, planteamos evaluar la percepción del ruido ambiental, determinar los niveles de ruido y el confort acústico en la BAN. Para ello encuestamos a 359 usuarios de la BAN, medimos los niveles de ruido y determinamos el bienestar acústico siguiendo la metodología establecida por el INDECOPI1 y el INSHT2 respectivamente. Las encuestas concluyeron que el 65.9% de los usuarios de la BAN perciben las salas de estudio como «poco silenciosas» y un 70.2% indica que el ambiente sonoro es «agradable». Los niveles de ruido oscilaron entre 44.1 y 54.2 dBA. Respecto al confort acústico, se dedujo que las salas Ciencias, Hemeroteca, Referencias, Ciencias Sociales, Agricultura y Tesis son acogedoras; sin embargo, los resultados no son precisos para toda la BAN, pues se encontraron diferencias significativas entre el PPDr-objetivo y el PPDr-subjetivo

The National Agricultural Library (BAN) is the leading library in agricultural and livestock issue of Peru. It provides services in nine reading rooms in two buildings. Evaluations of the perception and the acoustic comfort in reading rooms, as those of a library, had not been carried out up until now. As libraries are known for being one of the principal tools for professional development, it was considered to evaluate the perception of the environmental noise, to determine its noise levels and the acoustic comfort in the BAN. For this purpose, 359 BAN users were polled, noise levels were measured and acoustic comfort was determined following the methodology established by INDECOPI1 (National Institute for the Defense of Free Competition and the Protection of Intellectual Property) and INSHT (National Institute for Safety and Health at Work)2 respectively. It was found that 65,9% of BAN users perceive study rooms as «quiet» and 70,2% indicate that the sound environment is «comfortable». The noise levels ranged from 44,1 to 54,2 dBA. Concerning the acoustic comfort, it was established that the Sciences, Newspaper and Periodicals Library, References, Social Sciences, Agriculture and Thesis rooms are comfortable. However, the results are not accurate for the whole BAN, as significant differences between PPDn-objective and PPDn-subjective. were found

Cost-Effective Hearing Conservation: Regulatory and Research Priorities.

Hearing conservation programs (HCPs) mandated by the US Occupational Safety and Health Administration (OSHA) cost about $350/worker/year. Are they cost-effective? A cross-sectional model of the US adult population with and without HCPs incorporates (1) the American Medical Association's method for estimating binaural hearing impairment and whole-person impairment; (2) the model of the International Organization for Standardization (ISO) for estimating both age-related and noise-induced hearing loss; and (3) an acceptable cost of $50,000 per quality-adjusted life year. The ISO model's outputs were audiometric thresholds for groups of people with different age, sex, and noise exposure history. These thresholds were used to estimate cost per quality-adjusted life year saved for people in HCPs with different noise exposure levels. Model simulations suggest that HCPs may be cost-effective only when time-weighted average (TWA) noise exposures are ≥ 90 dBA. Enforcing existing regulations, requiring engineering noise control at high exposure levels, and using new methods that can document hearing protection device performance could improve cost-effectiveness. If the OSHA action level remains at 85 dBA-TWA, reducing the permissible exposure limit to the same level would simplify management and slightly improve cost-effectiveness. Research should evaluate employer compliance across industries, determine whether workers currently excluded from HCP regulations are at risk of noise-induced hearing loss, and develop cost-effective HCPs for mobile workers in construction, agriculture, and oil and gas drilling and servicing. Research on HCP cost-effectiveness could be extended to incorporate sensitivity analyses of the effects of a wider range of assumptions.

Contemporary noise-induced hearing loss (NIHL) prevention.

Hearing impairment caused by noise, traditionally called - depending on the duration of exposure - acute or chronic acoustic trauma, includes, in addition to presbyacusis, the most common adult population of hearing impaired. In Poland - according to the report of the Central Statistical Office (GUS, 2011), the number of workers employed in NDN exceeded the noise level (85 dB) is about 200 thousand, the highest in the mining, metal and metal products production, textiles and wood production. According to the Regulation of the Council of Ministers of on June 30, 2009, on the list of occupational diseases (Journal of Laws No. 132, item 1115), it is defined as "bilateral permanent hearing loss of the cochlear or sensory-nerve type, expressed as an increase in hearing threshold of at least 45 dB in the ear better heard, calculated as an arithmetic mean for frequencies 1,2 and 3 kHz. Hearing impairments also occur in the military and police during field training and in combat where the source of acoustic injuries are firearms and pulse-inducing explosions (as in some industries) with high C peak levels (Lc peak) Time to rise to a maximum of <1 ms. The prevalence of loud music listening, particularly by personal stereo players, is also affecting children and adolescents with audiometric hearing loss, according to the World Health Organization (WHO) estimates of around 15-20%. The preventive action strategy is defined by the European Union legislation and the national implementing legislation that reduces or eliminates the risk and reduces (if not eliminated), taking into account available technical and organizational solutions to minimize the risk of hearing damage. If you can not reduce the noise levels with technical and organizational methods, you need individual hearing protectors. Ear protectors may be equipped with electronic systems with active noise reduction (which can improve low and medium frequency performance), adjustable attenuation (improves speech intelligibility and perception of warning signals), and wireless communication for verbal communication.

Interventions to prevent occupational noise-induced hearing loss.

BACKGROUND: This is the second update of a Cochrane Review originally published in 2009. Millions of workers worldwide are exposed to noise levels that increase their risk of hearing disorders. There is uncertainty about the effectiveness of hearing loss prevention interventions. OBJECTIVES: To assess the effectiveness of non-pharmaceutical interventions for preventing occupational noise exposure or occupational hearing loss compared to no intervention or alternative interventions. SEARCH METHODS: We searched the CENTRAL; PubMed; Embase; CINAHL; Web of Science; BIOSIS Previews; Cambridge Scientific Abstracts; and OSH UPDATE to 3 October 2016. SELECTION CRITERIA: We included randomised controlled trials (RCT), controlled before-after studies (CBA) and interrupted time-series (ITS) of non-clinical interventions under field conditions among workers to prevent or reduce noise exposure and hearing loss. We also collected uncontrolled case studies of engineering controls about the effect on noise exposure. DATA COLLECTION AND ANALYSIS: Two authors independently assessed study eligibility and risk of bias and extracted data. We categorised interventions as engineering controls, administrative controls, personal hearing protection devices, and hearing surveillance. MAIN RESULTS: We included 29 studies. One study evaluated legislation to reduce noise exposure in a 12-year time-series analysis but there were no controlled studies on engineering controls for noise exposure. Eleven studies with 3725 participants evaluated effects of personal hearing protection devices and 17 studies with 84,028 participants evaluated effects of hearing loss prevention programmes (HLPPs). Effects on noise exposure Engineering interventions following legislationOne ITS study found that new legislation in the mining industry reduced the median personal noise exposure dose in underground coal mining by 27.7 percentage points (95% confidence interval (CI) -36.1 to -19.3 percentage points) immediately after the implementation of stricter legislation. This roughly translates to a 4.5 dB(A) decrease in noise level. The intervention was associated with a favourable but statistically non-significant downward trend in time of the noise dose of -2.1 percentage points per year (95% CI -4.9 to 0.7, 4 year follow-up, very low-quality evidence). Engineering intervention case studiesWe found 12 studies that described 107 uncontrolled case studies of immediate reductions in noise levels of machinery ranging from 11.1 to 19.7 dB(A) as a result of purchasing new equipment, segregating noise sources or installing panels or curtains around sources. However, the studies lacked long-term follow-up and dose measurements of workers, and we did not use these studies for our conclusions. Hearing protection devicesIn general hearing protection devices reduced noise exposure on average by about 20 dB(A) in one RCT and three CBAs (57 participants, low-quality evidence). Two RCTs showed that, with instructions for insertion, the attenuation of noise by earplugs was 8.59 dB better (95% CI 6.92 dB to 10.25 dB) compared to no instruction (2 RCTs, 140 participants, moderate-quality evidence). Administrative controls: information and noise exposure feedbackOn-site training sessions did not have an effect on personal noise-exposure levels compared to information only in one cluster-RCT after four months' follow-up (mean difference (MD) 0.14 dB; 95% CI -2.66 to 2.38). Another arm of the same study found that personal noise exposure information had no effect on noise levels (MD 0.30 dB(A), 95% CI -2.31 to 2.91) compared to no such information (176 participants, low-quality evidence). Effects on hearing loss Hearing protection devicesIn two studies the authors compared the effect of different devices on temporary threshold shifts at short-term follow-up but reported insufficient data for analysis. In two CBA studies the authors found no difference in hearing loss from noise exposure above 89 dB(A) between muffs and earplugs at long-term follow-up (OR 0.8, 95% CI 0.63 to 1.03 ), very low-quality evidence). Authors of another CBA study found that wearing hearing protection more often resulted in less hearing loss at very long-term follow-up (very low-quality evidence). Combination of interventions: hearing loss prevention programmesOne cluster-RCT found no difference in hearing loss at three- or 16-year follow-up between an intensive HLPP for agricultural students and audiometry only. One CBA study found no reduction of the rate of hearing loss (MD -0.82 dB per year (95% CI -1.86 to 0.22) for a HLPP that provided regular personal noise exposure information compared to a programme without this information.There was very-low-quality evidence in four very long-term studies, that better use of hearing protection devices as part of a HLPP decreased the risk of hearing loss compared to less well used hearing protection in HLPPs (OR 0.40, 95% CI 0.23 to 0.69). Other aspects of the HLPP such as training and education of workers or engineering controls did not show a similar effect.In three long-term CBA studies, workers in a HLPP had a statistically non-significant 1.8 dB (95% CI -0.6 to 4.2) greater hearing loss at 4 kHz than non-exposed workers and the confidence interval includes the 4.2 dB which is the level of hearing loss resulting from 5 years of exposure to 85 dB(A). In addition, of three other CBA studies that could not be included in the meta-analysis, two showed an increased risk of hearing loss in spite of the protection of a HLPP compared to non-exposed workers and one CBA did not. AUTHORS' CONCLUSIONS: There is very low-quality evidence that implementation of stricter legislation can reduce noise levels in workplaces. Controlled studies of other engineering control interventions in the field have not been conducted. There is moderate-quality evidence that training of proper insertion of earplugs significantly reduces noise exposure at short-term follow-up but long-term follow-up is still needed.There is very low-quality evidence that the better use of hearing protection devices as part of HLPPs reduces the risk of hearing loss, whereas for other programme components of HLPPs we did not find such an effect. The absence of conclusive evidence should not be interpreted as evidence of lack of effectiveness. Rather, it means that further research is very likely to have an important impact.

Commentary on the regulatory implications of noise-induced cochlear neuropathy.

OBJECTIVE: A discussion on whether recent research on noise-induced cochlear neuropathy in rodents justifies changes in current regulation of occupational noise exposure. DESIGN: Informal literature review and commentary, relying on literature found in the authors' files. No formal literature search was performed. STUDY SAMPLE: Published literature on temporary threshold shift (TTS) and cochlear pathology, in humans and experimental animals, as well as the regulations of the US Occupational Safety and Health Administration (OSHA). RESULTS: Humans are less susceptible to TTS, and probably to cochlear neuropathy, than rodents. After correcting for inter-species audiometric differences (but not for differences in susceptibility), exposures that caused cochlear neuropathy in rodents already exceed OSHA limits. Those exposures also caused "pathological TTS" (requiring more than 24 h to recover), which does not appear to occur with human broadband noise exposure permissible under OSHA. CONCLUSION: It would be premature to conclude that noise exposures permissible under OSHA can cause cochlear neuropathy in humans.

Evaluación epidemiológica de la exposición a ruido en trabajadores de policía local y bomberos / Epidemiological evaluation of noise exposure in workers local police and firefighters

La discusión acerca de la exclusión de determinados puestos de trabajo del ámbito de la aplicación de la Ley 31/1995, finalizó con la Sentencia del Tribunal de Justicia de las Comunidades Europeas (12//01/2006). Objetivos: Conocer el riesgo de presentar una audiometría anormal relacionada con el trabajo, en aras de poder establecer relación entre el puesto y la exposición. Material y Métodos: Estudio de casos y controles realizado durante el periodo 2006-2010 entre agentes de Policía Local, Bomberos y personal de Administración. De una población accesible de 881 trabajadores se reclutaron a 631 que cumplían criterios de inclusión. De forma aleatoria y estratificada por sexo y edad, la muestra seleccionada fue de 389 (207 casos y 182 controles). Se realizó un análisis estadístico mediante contraste de medias independientes y porcentajes y como medida de asociación se calculó la Odds Ratio (OR) para los grupos de estudio y análisis multivariante de regresión logística así como curvas ROC. Resultados: En el análisis univariante, edad, puesto de trabajo (POL) y umbrales OSHA presentaron diferencias significativas, con una OR de 2,8 (p<0.001) en el grupo de Policía Local. En el multivariante, edad, umbrales OSHA y puesto de Policía Local (OR 2,8), siguen siéndolo. El área bajo la curva ROC fue para OSHA (0,815). Conclusiones: El puesto de policía local muestra mayor riesgo de lesión neurosensorial que el de administrativo; y la evaluación epidemiológica de la salud se muestra como herramienta eficaz para la evaluación de los riesgos (AU)

The discussion about the exclusion of certain jobs in the field of application of Law 31/1995, ended with the judgment of the Court of Justice of the European Communities (12 / 01/2006). Objective: to know the risk of abnormal audiometry work-related, in order to be able to establish relationship between the position and exposure. Material and Methods: a case-control study conducted during the period 2006-2010 among local police officers, firefighters and personal Administration. An accessible population of 881 workers were recruited 631 who met inclusion criteria. Random and stratified by sex and age, the selected sample was 389 (207 cases and 182 controls). Statistical analysis was performed using contrast independent means and percentages and as a measure of association calculated the odds ratio (OR) for groups of multivariate analysis and logistic regression analysis and ROC curves. Results: in the univariate analysis, age, job (POL) and OSHA thresholds differ significantly, with an odds ratio of 2.8 (p<0.001) in the group of local police. In multivariate, age, OSHA thresholds and local police station (OR 2.8), remain so. The area under the ROC curve was to OSHA (0.815) Conclusions: the local police station shows higher risk of sensoneural injury than administrative staff, and the epidemiological assessment of health is shown as an effective tool for risk assessment (AU)

Civilian law: from occupational medicine to occupational event.

Civilian law:from occupational medicine to occupational event. Despite the growing importance of objective measurements, the health effects of many occupational risk factors are currently not fully quantified. Occupational noise, as a widespread risk factor, is illustrative in this regard; there is a strong body of evidence linking it to an important health outcome (hearing loss), but it is less decisively associated with others (such as psychological disorders). It is also distinct from environmental noise, and therefore falls under the responsibility of employers as well as individuals. Noise-induced hearing loss (NIHL) is, at present, incurable and irreversible. However, it is preventable, if effective and global hearing conservation programmes can be implemented. These programmes should not be isolated efforts, but should be integrated into the overall hazard prevention and control programme of the workplace. Belgian law encompasses a set of provisions for prevention and the protection of the health and safety of workers within the workplace, including aspects pertaining to the hygiene of the workplace and psychosocial aspects at work (stress, violence, bullying and sexual harassment, among others). In principle, combating environmental noise is fully addressed in this country. However, other levels of policy-making also play an important role in this regard. For example, the federal government is in charge of product standards, and therefore also of noise emission standards for products. The interpretation and enforcement of Belgian legislation on well-being at work converts European directives and international agreements on well-being at work into Belgian law.

[Clinical and hygienic aspects of occupational neurosensory deafness in civil aviation flight personnel].

The article covers implementation of regulatory and legal concepts in prevention of risk caused by hazardous effects of noise in civil aviation flight personnel. The authors analyzed case histories of civil aviation flight personnel patients examined in occupational diseases clinic, with first diagnosed occupational neurosensory deafness.

[The role of information and training for workers on the correct use of earplugs in assessing real noise attenuation with E-A-RfitTM system]. / Il peso di in\formazione e formazione dei lavoratori sul correctto utilizzo di inserti auricolari nella valutazione del reale abbattimento del rumore mediante il sistema E-A-Rfit ™.

BACKGROUND: Laboratory levels of perceived noise attenuation as heard using earplugs are always higher than the real levels that can be achieved at the workplace. The employer is bound by law to supply individual hearing protection devices (HPDs), to assess their efficiency and efficacy, and also to inform and train workers on the correct use of HPDs. OBJECTIVES: This study assessed the real "personal attenuation rating" (PAR) of HPDs  used by workers at the workplace, before (PAR A) and after (PAR B) specific and individual training. These values were also compared with the theoretical  "single number rating" (SNR) provided by the manufacturer. METHODS: The study covered all the 65 male employees of an awnings factory, using the E-A-RfitTM computerized method, which can measure PARs, based on the difference between sound pressures recorded by an "outside" microphone and an "inside" microphone placed in the auditory canal, with earplugs inserted, before (PAR A) and after (PAR B), i.e., the specific and individual training described above. RESULTS/CONCLUSIONS: PARs B were always definitely higher than PARs A, both for all tested frequencies and the corresponding average values, which were automatically detected by E-A-RfitTM. Furthermore the same PARs B were  decidedly lower than the respective SNRs supplied by the manufacturer on the basis of laboratory assessments. These data prove that specific and individual training for workers improves the performance of earplugs, contributing to a more appropriate secondary prevention of the effects of noise on hearing; they also prove that the real attenuation recorded in workers are always lower than those supplied by the manufacturer of the devices. It is recommended that the E-A-RfitTM system, which allowed these results to be achieved objectively, should be normally used to assess exposure to noise in workers, when HPDs are worn.

Noise exposure of commercial divers in the Norwegian Sector of the North Sea.

It is well known that exposure to high noise levels can adversely affect human hearing. Legislation exists in Europe to control or restrict the level of noise to which employees may be exposed during the course of their work. While the noise levels to which a worker may be exposed is well defined in air, human sensitivity to noise is different in high-pressure and mixed-gas conditions. Relatively little research exists to define human hearing in these circumstances, and few measurements exist of the levels of noise to which divers working in these conditions are exposed. A study using specially designed equipment has been undertaken in Norwegian waters to sample the noise levels present during typical saturation dives undertaken by commercial divers working in the Norwegian oil and gas industry. The divers were working in heliox at depths of 30 msw and 120 msw. It found noise levels were generally dominated by self-noise: flow noise while breathing and communications. The noise levels, both when corrected for the difference in hearing sensitivity under pressure in mixed gas and uncorrected, would exceed legislated limits for noise exposure in a working day without the use of noisy tools.

Application of the Extreme Value Distribution to Estimate the Uncertainty of Peak Sound Pressure Levels at the Workplace.

OBJECTIVES: The purpose of this article is to develop a method for the statistical inference of the maximum peak sound pressure level and of the associated uncertainty. Both quantities are requested by the EU directive 2003/10/EC for a complete and solid assessment of the noise exposure at the workplace. METHODS: Based on the characteristics of the sound pressure waveform, it is hypothesized that the distribution of the measured peak sound pressure levels follows the extreme value distribution. The maximum peak level is estimated as the largest member of a finite population following this probability distribution. The associated uncertainty is also discussed, taking into account not only the contribution due to the incomplete sampling but also the contribution due to the finite precision of the instrumentation. RESULTS: The largest of the set of measured peak levels underestimates the maximum peak sound pressure level. The underestimate can be as large as 4 dB if the number of measurements is limited to 3-4, which is common practice in occupational noise assessment. The extended uncertainty is also quite large (~2.5 dB), with a weak dependence on the sampling details. CONCLUSIONS: Following the procedure outlined in this article, a reliable comparison between the peak sound pressure levels measured in a workplace and the EU directive action limits is possible. Non-compliance can occur even when the largest of the set of measured peak levels is several dB below such limits.

Is it reasonable to use 1 and 8 kHz anchor points in the medico-legal diagnosis and estimation of noise-induced hearing loss?

BACKGROUND: In the United Kingdom, use of 1 and 8 kHz as anchor point frequencies has been recommended for the medico-legal diagnosis and estimation of noise-induced hearing loss. There appear to be four assumptions behind the use of 1 and 8 kHz anchor point approach: (i) The frequencies of 1 and 8 kHz are not damaged by noise; therefore, the measured hearing thresholds at the said frequencies solely reflect age-related hearing loss, even in the noise-exposed; (ii) The hearing thresholds at 1 and 8 kHz are a valid predictor of the likely age-related hearing loss thresholds at the other frequencies; (iii) Age and noise damage are always completely additive; (iv) Individual's susceptibility to age and noise damage is not proportionate. Doubts have been expressed in the medical circles about the legitimacy and validity of their use as anchor points. OBJECTIVE OF REVIEW: Is it reasonable to use 1 and 8 kHz anchor points in the medico-legal diagnosis and estimation of noise-induced hearing loss? TYPE OF REVIEW: Medico-legal. SEARCH STRATEGY: Literature search; Medline, Embase, Internet, and medico-legal records. EVALUATION METHOD: Equating and comparing the assumptions in the anchor point approach with the information in medical literature. RESULTS: Based upon the information in medical literature, technical reports, and professional statements, the assumptions behind the use of anchor point approach cannot be reliably substantiated. CONCLUSIONS: 'Carte Blanche' use of 1 and 8 kHz anchor points is probably unreasonable and may well be unsafe in the medico-legal diagnosis and estimation of noise-induced hearing loss.