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workers, building, architect

NORA Manufacturing Sector Strategic Goals

9278613 - Factors Affecting Hearing Conservation Program

Start Date: 10/1/1999
End Date: 3/31/2010

Principal Investigator (PI)
Name: Cheryl Estill
Phone: 513-841-4476
Organization: NIOSH
Sub-Unit: DSHEFS
Funded By: NIOSH

Primary Goal Addressed

Secondary Goal Addressed


Attributed to Manufacturing


Project Description

Short Summary

This study will will identify factors having the most impact on the effectiveness of hearing conservation programs (HCPs). Noise-induced hearing loss (NIHL) can be prevented when good hearing conservation practices are adhered to in the workplace. However objective, systematic measures of the effectiveness of HCPs must be developed to track whether prevention of NIHL is successful. The study evaluates three plant sites with well-established industrial HCPs which varied in the degree of compliance with the OSHA standard. Noise level, audiometric, and work history information for 10,000 employees from three manufacturing plants with differing hearing conservation programs are being evaluated. The results will be used to develop criteria for evaluation of HCPs and identify program components most likely to be associated with an effective prevention program. An evaluation of impact noise was also examined for one plant site.


The 1983 OSHA Hearing Conservation Amendment (HCA) allows employers flexibility in how they implement various components of the hearing conservation program. The objective of this research is to develop a systematic and comprehensive approach to the evaluation of hearing conservation programs (HCP) which are required as part of the OSHA HCA. The study will identify factors associated with effective hearing conservation programs (HCP) using data from three established programs (two automotive manufacturing plants and one food processing plant). The study will also develop methods for measuring effectiveness of these hearing conservation programs by examining organizational practices in the implementation of the OSHA standard and determining whether noise exposures have declined as a result of implementation of a HCP.

At three manufacturing plants, data routinely collected as part of the OSHA HCA standard were supplemented with program audits and employee-centered focus groups to gauge company commitment to health and safety activities. These supplemental data were used to better understand how implementation of the program has changed over time and what factors impacted these changes. The study examines 15-30 years of longitudinal hearing data in relation to noise exposure, degree of compliance with OSHA standards, changes in hearing protection use, and non-occupational factors. Longitudinal models describing rates of hearing loss as a function of noise, age and other risk factors will be compared across study plants which have varying degrees of compliance to the hearing conservation standard to assess whether proactive programs do a better job of protecting workers' hearing relative to those that implement the minimum requirements under the standard.

From each of the three manufacturing plants in the study available data records normally kept by the companies to comply with the OSHA HCA standard such as audiometric test results and noise measurement data were obtained. Fifteen to 30 years of employee work history and audiometric test results were collected. Noise measurement data were also collected, though these data were typically limited to only a few years. The noise and hearing loss databases constructed from this project represent the largest longitudinal study of hearing and noise exposure in contemporary workers (N=10,000, 15-30 years of follow-up). These data were used to better understand how implementation of the program has changed over time and what factors impacted these changes.

All of these data have been collected and analyses are continuing. A contractor is conducting the analyses. Preliminary analyses are completed. During FY09, final data analysis will be completed. The draft manuscript will be written and peer reviewed. By the end of FY09 the manuscript will be submitted to a journal.


The project objective is to develop a systematic and comprehensive approach to the evaluation of hearing conservation programs (HCP) required as part of the OSHA HCA. The results will highlight (1) how the standard has affected noise exposures over time and (2) whether proactive programs are better or the same as minimally compliant programs in reducing the rate of hearing loss over time. The study will also identify program components and practices that best predict program effectiveness using both qualitative and quantitative data. The methods and results of this study will be relevant to evaluating current OSHA noise and hearing regulations.

Mission Relevance

There are more than 30 million U.S. workers exposed to noise levels in excess of 85 dBA, a level that is associated with a significant risk of noise induced hearing loss (NIHL). NIHL is one of the most common occupational diseases and the second most self-reported occupational illness or injury. Although hearing conservation programs (HCPs) were mandated by the OSHA Hearing Conservation Amendment of 1983, these programs have not been systematically evaluated to examine whether they prevent NIHL. This project includes a systematic and comprehensive public health approach to evaluating workplace hearing conservation programs. We will evaluate three hearing conservation programs at two automobile manufacturing plants and one food processing plant. Audiometric data, employee noise exposure levels, and work history records will be used to identify the factors of hearing conservation programs that make them effective. A significant portion of hearing loss occurs among employees in the manufacturing sector. This study will evaluate hearing conservation programs at three manufacturing sector plants. For the hearing loss sector, this study will identify hearing loss risk factors, especially those risk factors associated with hearing conservation programs.