To account for use of hearing protection devices (HPDs) in retrospective noise exposure assessment, adjust noise exposure estimates accordingly, and validate the adjusted estimates.
A previous study in the same working population showed a stronger relation for noise and acute myocardial infarction among those who did not wear HPD. Because accurate noise exposure assessment is complicated by the use of HPD, we previously developed a multilevel model of the likelihood of HPD use for British Columbia (Canada) lumber mill workers. Historical estimates of noise exposure can be adjusted according to models predictions and a reduction in misclassifying workers, exposure is expected.
Work history and exposure information were obtained for 13,147 lumber mill workers followed from 1909 until 1998. Audiometric data for the cohort, including hearing threshold levels at several pure tone frequencies, were obtained from the local regulatory agency for the period from 1978 to 2003. Following the modeling of HPD use, noise estimates were adjusted according to models predictions and attenuation factors based on existing research and standards. Adjusted and unadjusted noise metrics were compared by investigating their ability to predict noise-induced hearing loss.
We showed a 4-fold increase in the noise exposure and hearing loss slope, after adjusting for HPD use, while controlling for gender, age, race, as well as medical and non-occupational confounding variables.
While the relative difference before and after adjustment for use of HPD is considerable, we observed a subtle absolute magnitude of the effect. Using noise-induced hearing loss as a 'gold standard' for testing the assessment of retrospective noise exposure estimates should continue to be investigated.
The effects on hearing thresholds, sound attenuation, and consonant discrimination of wearing a balaclava under hearing-protecting earmuffs were studied. This combination is commonly worn during cold weather military operations. One group of 20 normal-hearing adults (10 male and 10 female subjects) was tested. Within-subject measurements were made of diffuse-field hearing thresholds from 0.25 kHz to 8 kHz and consonant discrimination in quiet with the ears unoccluded and protected with the earmuffs alone and with the balaclava worn full face or rolled. Attenuation was derived from the protected and unoccluded thresholds at each frequency. When the balaclava was worn full face, attenuation decreased by 16 to 18 dB, relative to the muff alone, below 6.3 kHz. With the balaclava worn as a cap, there was an inverted U-shaped decrement in attenuation of 18 to 27 dB from 0.25 Hz to 4 kHz. Consonant discrimination decreased by 7% with the muffs alone. These findings underscore the importance of assessing protective equipment under the conditions in which it will be worn.
The Canadian military instituted a hearing conservation program over 45 yr ago. Yet the prevalence of noise-induced hearing loss is escalating. A focus group study involving four combat arms occupations was carried out to probe individuals' knowledge, attitudes, and behaviors relating to hearing loss prevention to find ways to improve compliance.
One group each of 4-5 Infantry Soldiers, Artillerymen, Armored Soldiers, and Combat Engineers, with the rank of Warrant Officer, Sergeant, or Master Corporal, and at least 5 yr of service participated. Discussions were led by a Moderator and recorded by an Assistant Moderator. Questions posed related to susceptibility and consequences of hearing loss, benefits and drawback of hearing protection, and preferences.
Age range was 28-48 yr and length of service 10-30 yr. Individuals were exposed to noise from weapons, explosives, vehicles, and aircraft. Infantry Soldiers and Artillerymen had confirmed moderate to severe hearing loss. Armored Soldiers and Combat Engineers had not perceived a change in hearing. Main concerns of using hearing protection were interference with detection and localization of auditory warnings, and perception of orders. Devices were often incompatible with other gear and difficult to fit.
Good hearing was critical to the occupations studied. Difference in hearing loss among groups was related to type and level of noise exposure. Loss of hearing and/or the use of hearing protection compromised situational awareness, exchange of information, and auditory task performance. Participants favored opportunities to try recommended devices, policies governing use, and sufficient funding to ensure protection for both regular and special forces.
In a cohort study of lumber mill workers' exposure to noise and incidence of heart disease, initial noise estimates were likely overestimated because they did not account for reductions afforded by the use of hearing protection. As such information was seldom available for individual workers, modeling was necessary to predict hearing protection use and derive adjusted noise measures.
To develop a multilevel model of the likelihood of use of hearing protection devices (HPDs) for British Columbia (Canada) lumber mill workers.
The study population included 13,147 workers in 14 sawmills for whom we had information on HPD use. Subjects self-reported their use of hearing protectors during routine hearing tests over their work history period. Separate multilevel logistic regression models with increasing complexity were developed for a subcohort of workers with complete information (n = 1493) and for a subcohort comprised subjects with hearing tests coinciding with their jobs (n = 10 203). The models included random intercepts for worker and for sawmill.
HPD use was associated in both subcohorts with factors such as noise exposure and age. We also showed that specific jobs (such as sawfiling) and departments (planer, in particular) were strongly associated with the use of HPDs. The model illustrates the quantitative importance of including a hierarchical structure which allows for explaining potential sources of outcome variability.
We developed a hierarchical model to predict hearing protection use to enable correction of exposure assessments for use in retrospective epidemiological studies. We showed that this was feasible even in the absence of complete determinant information.
Most farmers are exposed to potentially hazardous noise levels through many of their work activities, such as operating tractors, grain dryers, and chain saws. Rates of noise-induced hearing loss in this group are high. Although this condition is preventable through the use of hearing protection, rates of protective device use are low. Understanding factors influencing the use of hearing protection devices will provide direction for programs to increase their use and decrease risk of noise-induced hearing loss.
A study was designed using the Pender Health Promotion Model to identify factors affecting farmers' use of hearing protection devices.
Model testing was conducted with a convenience sample of 139 farmers. Prior to model testing, existing instruments designed to measure concepts from the Health Promotion Model were modified for use with farmers through interviews, validity testing with an expert panel, and reliability testing with first a small (n = 36) then a second larger (n = 139) convenience sample of farmers. Instruments measuring cognitive and affective factors related to hearing protection device use were administered to farmers at a regional farm show in the Midwest.
A logistic regression analysis identified interpersonal support, barriers, and situational influences as statistically significant predictors of this health behavior, correctly predicting 78% of the cases. Results of model testing were consistent with results of previous studies of Health Promotion Model variables with other worker groups' use of hearing protection.
Information from this study can be used to design and evaluate interventions to promote hearing protection device use among farmers and reduce the level of noise-induced hearing loss in this high-risk and underserved worker group.
The purpose of the present study was to investigate possible gender differences regarding psychometric scales measuring risk perception in noisy situations, attitudes towards loud music, perceived susceptibility to noise, and individual norms and ideals related to activities where loud music is played. In addition the purpose was to analyze whether these variables are associated with protective behavior such as the use of hearing protection. A questionnaire was administered to a Swedish sample including 543 adolescents aged 16 to 20. The result revealed significant gender differences for all the psychometric scales. In addition, all psychometric measures were associated with hearing protection use in musical settings. Contrary to previous studies, gender did not contribute to any explanation of protective behavior by itself in the analysis. One conclusion is that although gender does not contribute by itself for the explanation of protective behavior, gender may affect psychological variables such as risk perception, attitudes and perceived susceptibility and that these variables may in turn be valuable for decision-making and protective behavior in noisy situations. Although women tend to be more 'careful' psychologically, they nevertheless tend to behave in the same way as men as regards actual noise-related risk taking.
Noise exposure remains one of the most ubiquitous of occupational hazards. Hearing conservation program legislation and the programs themselves were designed to lower risk of resulting occupational noise-induced hearing loss, but there has been no broad-based effort to assess the effectiveness of this policy.
The incidence of a 10-dB standard threshold shift was examined in a group of Canadian lumber mill workers, using annual audiogram series obtained from the Workers' Compensation Board of British Columbia for the period 1979-1996 and using Cox proportional hazard models.
Mean cumulative noise exposure was 98.1 dB-years. The audiograms from 22,376 individuals, among whom there were 2,839 threshold shifts of 10 dB or greater (i.e., a "standard threshold shift"), were retained in multivariable analyses. After adjusting for potential confounders, continuous use of hearing protection, and initial hearing tests later in the study period, the risk for standard threshold shift was reduced by 30%. Risk increased sixfold, however, in those with the highest noise exposure.
Hearing conservation programs may be effective in reducing overall incidence of hearing loss. In the absence of noise control at source, however, highly exposed workers remain at unnecessary risk.
The results from studies of loud noise exposure and acoustic neuroma are conflicting. A population-based case-control study of 451 acoustic neuroma patients and 710 age-, sex-, and region-matched controls was conducted in Sweden between 2002 and 2007. Occupational exposure was based on historical measurements of occupational noise (321 job titles summarized by a job exposure matrix) and compared with self-reported occupational noise exposure. We also evaluated self-reported noise exposure during leisure activity. Conditional logistic regression was used to estimate odds ratios. There was no statistically significant association between acoustic neuroma and persistent occupational noise exposure, either with or without hearing protection. Exposure to loud noise from leisure activity without hearing protection was more common among acoustic neuroma cases (odds ratio = 1.47, 95% confidence interval: 1.06, 2.03). Statistically significant odds ratios were found for specific leisure activities including attending concerts/clubs/sporting events (odds ratio = 1.82, 95% confidence interval: 1.09, 3.04) and participating in workouts accompanied by loud music (odds ratio = 2.84, 95% confidence interval: 1.37, 5.89). Our findings do not support an association between occupational exposure to loud noise and acoustic neuroma. Although we report statistically significant associations between leisure-time exposures to loud noise without hearing protection and acoustic neuroma, especially among women, we cannot rule out recall bias as an alternative explanation.
The hearing thresholds of male sheet-metal workers have been studied in a longitudinal investigation with pure tone audiometry during three periods covering 1972-1987. Using these data, the hearing threshold shifts were calculated in various age groups. When the annual rate of mean hearing threshold shift over the frequency range 2-8 kHz was considered, it was not possible to establish a difference in the threshold shift between noise-exposed groups and an otologically normal 'highly screened' male population from ISO 7029, database A. The correction for ageing in the noise-exposed group according to the empirical formula in ISO 1999 (1990) is discussed. The results show that a hearing conservation programme including effective use of hearing protectors and reduction of noise emission levels can eliminate noise-induced hearing threshold shifts and progressive hearing loss.
The aim of this study was to investigate the association of noise sensitivity with self-reported hearing disability and hearing levels, with consideration of the role of self-reported history of noise exposure and use of hearing protectors. The study is based on the Finnish Twin Cohort. In 1988, a noise questionnaire was sent to 1005 twin pairs, 1495 individuals (688 men, 807 women) replied. The age range was 31-88 years. Information on some potential confounders was obtained from the questionnaire in 1981 for the same individuals. A subsample of thirty-eight elderly women with noise sensitivity response from 1988 had audiometry data from 2000 to 2001. Noise sensitivity was associated with self-reported hearing disability among all subjects [odds ratio (OR) 1.55, 95% confidence interval (CI) 1.14-2.12] and among women (OR 1.90, 95% CI 1.19-3.04), but no-more significantly among men (OR 1.31, 95% CI 0.86-1.98). The association was primarily seen among younger subjects (50 years or less). The difference between noise sensitive and non-noise sensitive elderly women in the average of thresholds at frequencies of 0.5-4 kHz in the better ear was not significant (Pr = 0.18). Noise sensitivity did not modify the association of hearing disability with the self-reported history of occupational noise exposure. Noise sensitivity was associated with the use of hearing protectors at work. The study shows the importance of recognizing the noise sensitive in noise effect studies, since sensitivity in annoyance has implications in most of the effect categories.