Verificación de niveles de atenuación de protectores auditivos tipo copa en trabajadores del sector Hidrocarburos / Verifying the attenuation levels of earmuff hearing protectors in Oil & Gas workers / Verificando os níveis de atenuação dos protetores auditivos de abafador em trabalhadores de petróleo e gás

RESUMEN Objetivo Verificar los niveles de atenuación de dos tipos de protectores auditivos de copa bajo condiciones reales de operación. Métodos Se realizó un diseño experimental de medidas repetidas de los niveles de presión sonora al interior y exterior de los protectores auditivos, realizando mediciones de ruido bajo circunstancias habituales de trabajo para operadores de una planta de hidrocarburos. Posteriormente, se determinaron las diferencias entre los niveles de atenuación establecidos por el fabricante, los niveles de atenuación ajustados bajo el método recomendado por NIOSH y los niveles de atenuación obtenidos experimentalmente. Resultados Los valores de atenuación ofrecidos por los fabricantes difieren de los obtenidos experimentalmente, siendo estos últimos, menores en todos los casos del estudio. Los valores de atenuación de los protectores auditivos ajustados bajo el método NIOSH alcanzaron valores más cercanos a los experimentales. Conclusiones La variabilidad entre los valores de atenuación teóricos y experimentales, permiten establecer que las estimaciones de los niveles de atenuación obtenidos en condiciones controladas no consideran aspectos que en condiciones reales de uso afectan la eficiencia del protector auditivo. Este estudio plantea la necesidad de implementar programas integrales de protección auditiva, que permitan considerar variables asociadas a la eficacia del dispositivo en condiciones de uso, a través de la aplicación de pruebas de ajuste o en su defecto a través de la aplicación de los factores de ajuste sugeridos por NIOSH, con el fin de realizar una adecuada selección que permita alcanzar un control efectivo para el ruido.

ABSTRACT Objective To verify the attenuation levels of two types of earmuffs under real operating conditions. Materials and Methods A study with experimental design was carried out to obtain repeated measurements of the sound pressure levels inside and outside hearing protectors in a sample of workers of an oil and gas company working under normal process and exposure conditions. The results allowed determining differences between the attenuation levels established by the manufacturer, the adjusted attenuation levels under the NIOSH method, and the attenuation levels obtained experimentally. Results The attenuation values established by the manufacturers are lower than those ones obtained under actual use conditions in all cases evaluated. Likewise, the attenuation values of the hearing protectors, once adjusted under the NIOSH method, reached values much closer to those obtained experimentally. Conclusions The variability between theoretical attenuation values and experimental values allows concluding that the attenuation levels obtained under controlled laboratory conditions do not take into account certain characteristics that, based on their use, affect the efficiency of the hearing protection device. This study encourages the implementation of comprehensive hearing protection programs that consider variables such as hearing protection effectiveness, under real use conditions, by applying fit tests or other adjustment factors like the one suggested by NIOSH. This would ensure an adequate selection that aims at achieving an effective control of this risk factor.

RESUMO Objetivo Verifique os níveis de atenuação de dois tipos de protetores auriculares em condições reais de operação. Métodos Foi realizado um projeto experimental de medições repetidas dos níveis de pressão sonora dentro e fora dos protetores auditivos, fazendo medições de ruído em condições normais de trabalho para operadores de uma usina de hidrocarbonetos. Posteriormente, foram determinadas as diferenças entre os níveis de atenuação estabelecidos pelo fabricante, os níveis de atenuação ajustados pelo método recomendado pelo NIOSH e os níveis de atenuação obtidos experimentalmente. Resultados Os valores de atenuação oferecidos pelos fabricantes diferem daqueles obtidos experimentalmente, sendo este último menor em todos os casos do estudo. Os valores de atenuação dos protetores auditivos ajustados pelo método NIOSH atingiram valores mais próximos aos experimentais. Conclusões A variabilidade entre os valores de atenuação teórica e experimental permite estabelecer que as estimativas dos níveis de atenuação obtidos em condições controladas não consideram aspectos que, em condições reais de uso, afetam a eficiência do protetor auditivo. Este estudo levanta a necessidade de implementar programas abrangentes de proteção auditiva que permitam considerar variáveis associadas à efetividade do dispositivo em condições de uso, através da aplicação de testes de adaptação ou, na sua falta, através da aplicação de ajuste sugerido pelo NIOSH, a fim de fazer uma seleção adequada para obter um controle eficaz do ruído.(AU)

Evaluation of hearing protection used by police officers in the shooting range / Avaliação da proteção auditiva utilizada por policiais em estande de tiros

Introduction: Impact noise is characterized by acoustic energy peaks that last less than a second, at intervals of more than 1 s. Objective: To quantify the levels of impact noise to which police officers are exposed during activities at the shooting range and to evaluate the attenuation of the hearing protector. Methods: Measurements were performed in the shooting range of a military police department. An SV 102 audiodosimeter (Svantek) was used to measure sound pressure levels. Two microphones were used simultaneously: one external and one insertion type; the firearm used was a 0.40 Taurus® rimless pistol. Results: The values obtained with the external microphone were 146 dBC (peak), and a maximum sound level of 129.4 dBC (fast). The results obtained with the insertion microphone were 138.7dBC (peak), and a maximum sound level of 121.6 dBC (fast). Conclusion: The findings showed high levels of sound pressure in the shooting range, which exceeded the maximum recommended noise (120 dBC), even when measured through the insertion microphone. Therefore, alternatives to improve the performance of hearing protection should be considered. .

Introdução: O ruído de impacto é caracterizado por apresentar picos de energia acústica de duração inferior a um segundo, em intervalos superiores a um segundo. Objetivo: Quantificar os níveis de ruído de impacto a que o policial militar fica exposto durante atividades de tiro com armas de fogo e analisar a atenuação do protetor auricular utilizado. Método: As medições foram realizadas no estande de tiros de um Batalhão da Polícia Militar. Para a medição dos níveis de pressão sonora foi utilizado um audiodosímetro modelo SV 102 (Svantek). Foram utilizados dois microfones simultaneamente: um externo e outro tipo inserção, e a arma utilizada foi a pistola calibre 40, da marca Taurus®. Resultados: Os valores obtidos no microfone externo foram de 146 dBC (pico) e ruído máximo de 129,4 dBC (fast). Os resultados obtidos no microfone de inserção foram de 138,7 dBC (pico) e ruído máximo de 121,6 dBC (fast). Conclusão: Nossos achados evidenciaram elevados níveis de pressão sonora no estande de tiros, que ultrapassaram os limites máximos recomendados (120 dBC), mesmo em medição com microfone de inserção. Portanto, alternativas para melhorar o desempenho da proteção auditiva devem ser consideradas pela equipe de segurança da corporação. .

What do we know about hearing protector comfort?

The purpose of the present article is to review comfort studies on hearing protector devices. Comfort is probably the most important dimension for long-term worker acceptance and effective wear of hearing protectors in noise. A short digression has been made to introduce comfort work from the textile and clothing industries where models of comfort have been attempted and comfort research is much more sophisticated. Finally, presented are some recent efforts by NIOSH to examine issues of hearing protector comfort in greater detail. These efforts include a field study of a semi-custom earplug hearing protector.

Avaliação dos limiares auditivos com e sem equipamento de proteção individual / Pure tone audiometry with and without specific ear protectors

Os autores realizaram estudo caso-controle audiométrico em indivíduos com e sem protetor auricular auditivo. OBJETIVOS: O objetivo do estudo foi avaliar a real atenuação individual dado pelos protetores. MATERIAL E MÉTODO: Foram avaliados 30 indivíduos (ou 60 orelhas) de diferentes atividades profissionais, de ambos os sexos, com idades entre 20 e 58 anos, apresentando audição normal e tendo realizado repouso auditivo de 10 horas, submetidos a exame audiométrico com e sem protetor auricular auditivo, no período de fevereiro a julho de 2003, utilizando protetor tipo plugue. Avaliou-se as audiometrias nas vias aérea e óssea em freqüências de 500 a 4000Hz. RESULTADOS: Os resultados foram analisados estatisticamente e comparados aos dados fornecidos pelo fabricante. Assim se observou em ouvido real os níveis de atenuação auditiva obtidos com o uso destes produtos. CONCLUSÃO: Os resultados permitiram chegar à conclusão de que os índices fornecidos pelos fabricantes foram compatíveis com os que obtive nos testes.

The authors evaluated pure tone audiometry with and without specific ear protectors. AIM: The purpose of this case control study was to measure the level of sound attenuation by earplugs. MATERIAL AND METHODS: The evaluation included sixty ears of 30 subjects of both sexes, aged between 20 and 58 years, of various professional activities, with normal hearing thresholds, and following ten hours of auditory rest. The statistical results of pure tone audiometry at 500 to 4000 Hertz with and without specific ear protectors were analyzed. RESULTS: These results were compared with those provided by the ear protector manufacturer. CONCLUSION: The results show that the rate of sound reduction was similar to the manufacturer's specifications.

Effects of binaural electronic hearing protectors on localization and response time to sounds in the horizontal plane.

The effects of electronic hearing protector devices (HPDs) on localization and response time (RT) to stimuli were assessed at six locations in the horizontal plane. The stimuli included a firearm loading, telephone ringing and .5-kHz and 4-kHz tonebursts presented during continuous traffic noise. Eight normally hearing adult listeners were evaluated under two conditions: (a) ears unoccluded; (b) ears occluded with one of three amplitude-sensitive sound transmission HPDs. All HPDs were found to affect localization, and performance was dependent on stimuli and location. Response time (RT) was less in the unoccluded condition than for any of the HPD conditions for the broadband stimuli. In the HPD conditions, RT to incorrect responses was significantly less than RT to correct responses for 120 degrees and 240 degrees , the two locations with the greatest number of errors. The RTs to incorrect responses were significantly greater than to correct responses for 60 degrees and 300 degrees , the two locations with the least number of errors. The HPDs assessed in this study did not preserve localization ability under most stimulus conditions.

Eficácia da escolha do protetor auditivopequeno, médio e grande em programa de conservação auditiva / Efficacy in the choice of small, medium or large auricular protector under auditive conservation program

Objetivo: verificar a eficácia da escolha do protetor auditivo por tamanhos Pequeno, Médio, Grandeem um programa de conservação auditiva. Método: fizeram parte do estudo 30 indivíduos com audiçãonormal previamente avaliados, de 18 a 45 anos de idade, sendo 15 do gênero feminino e 15 do gêneromasculino, de Indústria Moveleira. Os sujeitos foram submetidos à avaliação audiológica convencional,audiometria em campo livre sem protetor auricular de inserção, com protetor tamanho universal e comtamanho adequado a cada indivíduo. Para análise estatística foi aplicado teste T Paramétrico paraanálise das diferenças. Resultados: O teste T Paramétrico pareado, mostrou significância, nacomparação dos protetores auriculares na freqüência de 4KHz. Conclusão: os resultados mostrarameficácia dos protetores auriculares pequeno e grande sobre os protetores tamanho universal em umprograma de conservação auditiva.

Purpose: to check the efficacy in the choice of small, medium or large auricular protector underauditive conservation program. Methods: 30 individuals, between 18 to 45-year old, with normal hearing,were part of the study previously evaluated: 15 women and 15 men, all working in a furniture industry.The individuals were submitted to the conventional audiological evaluation, audiometry in free fieldwithout auricular insertion protector, with universal size protector and with size adequate to eachindividual. For statistical analysis we used Parametric T test for analyzing the differences. Results: theParametric T test showed significance, during the comparison of the auricular protectors in the frequencyof 4KHz. Conclusion: these results demonstrate efficacy in choice of small, medium or large auditiveprotector, under auditive conservation program.

The risk of noise-induced hearing loss in the Danish workforce.

The causal association between occupational noise exposure and permanent hearing loss is well-documented and well-founded primary preventive approaches have been developed. However, documentation of the impact on the present prevalence of noise-induced hearing loss in the working population is limited. This study reports on the prevalence of noise-induced hearing loss in a population sample of 788 workers from 11 trades with expected high noise exposure levels and a reference group examined according to the same protocol. Full-shift A-weighted equivalent sound levels were recorded and pure tone audiometric examinations were conducted at the work sites in soundproof booths. Data were analyzed with multivariate regression techniques and adjusted for age, sex, ear disease, smoking and environmental noise exposure. An overall two-fold increased risk of hearing handicap (hearing threshold above 20 dB averaged across 2, 3 and 4 kHz for either ear) was observed in the noise exposed workers [odds ratio (OR) 1.99, 95% confidence interval (CI) 0.91-4.34]. Workers exposed for more than 20 years to an exposure level above 85 dB(A) had a three-fold increased risk (OR 3.05, 95% CI 1.33-6.99). Workers starting in noisy work during the last 10-15 years or workers below 30 years of age showed no increased risk of hearing handicap. This indicates that preventive measures enforced during the past 10-15 years to reduce noise exposure may have borne fruit. Systematic surveillance of noise and hearing levels in appropriate populations should still be included in an efficient hearing conservation program.

Hearing protector performance and standard deviation.

The attenuation performance of a hearing protector is used to estimate the protected exposure level of the user. The aim is to reduce the exposed level to an acceptable value. Users should expect the attenuation to fall within a reasonable range of values around a norm. However, an analysis of extensive test data indicates that there is a negative relationship between attenuation performance and the standard deviation. This result is deduced using a variation in the method of calculating a single number rating of attenuation that is more amenable to drawing statistical inferences. As performance is typically specified as a function of the mean attenuation minus one or two standard deviations from the mean to ensure that greater than 50% of the wearer population are well protected, the implication of increasing standard deviation with decreasing attenuation found in this study means that a significant number of users are, in fact, experiencing over-protection. These users may be disinclined to use their hearing protectors because of an increased feeling of acoustic isolation. This problem is exacerbated in areas with lower noise levels.

European standardisation of hearing protectors.

European legislation based on the New Approach requires that technical requirements for products are given in harmonised European standards. The Directive 89/686/EEC on Personal Protective Equipment came into force in 1995. The existence of product and testing standards is a prerequisite for the effective implementation of the directive. There was a need to develop several standards in a very short time period and the basic standards for hearing protectors have already been revised once. It is important to continue the validation of the standardised testing methods and requirement levels. This requires good co-operation and research between test laboratories and research institutes, especially as it is necessary to ensure new products comply with these technical requirements.

Instruction and the improvement of hearing protector performance.

Too often, in spite of the encouragement of those who advocate the removal of noise from the workplace as the preferred solution to noise exposure, hearing protectors are provided as the first line of defence against noise. Unfortunately hearing protectors are too often supplied with no real instruction or education in their use. This degrades their performance considerably. In this project the attenuation performance of one particular model of earplug was compared with and without instructions to test subjects. The instructions given were the most basic as commonly supplied on the plastic packaging containing the plugs. The attenuation performance (SLC80) of the plugs with the instructions was 16 dB greater than without the instructions. Overall performance was improved in every octave band with smaller associated standard deviations. The comparison showed that even with a very modest amount of instruction attenuation performance can be significantly improved.