Collections > Master's Papers > Gillings School of Public Health > A Method to Determine the Homogeneity of Noise Exposure Groups and Criteria for Enrollment into a Hearing Conservation Program
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Noise is a hazard which permeates the majority of work environments. In order to comply with the OSHA Hearing Conservation Amendment, all employees who are exposed to greater than 85 dBA as an 8 hour time weighted average need to be enrolled in a Hearing Conservation Program(HCP). In order to efficiently decide which employees need to be in the HCP, employees are often placed in exposure groups, in which it is assumed that all employees share the same exposure. In order to determine if exposure groups are truly homogeneous with respect to exposure, several statistical tests were employed. Three personal noise measurements were taken randomly on individuals in each exposure group. These measurements were used to form individual worker means. If the individual worker means from each exposure group were well within the 95% confidence interval around the estimated group mean, the exposure group was considered homogeneous. An additional test, the random-effects analysis of variance model, was used to determine the between-worker component of variance. If a substantial proportion of the total variance was attributable to the between-worker component, employees in the exposure group may be experiencing different exposure profiles. In this study 157 personal noise measurements were made on 7 exposure groups. Only 1 of the 7 groups was considered homogeneous. If exposure groups which are not homogeneous are placed into a HCP, there could be misclassification of employees and waste of company resources. In deciding if a group which is homogeneously exposed, should be placed in a HCP, the percentage of measurements that are greater than 85 dBA may be employed. In this study all of the exposure groups, except one, would be placed in a HCP.