activities, and outputs was used to assess the relevance of the program’s research. End outcomes and intermediate outcomes were examined to evaluate the impact of the program’s research. Illustrative examples of each of these terms as used in this report are provided in Box 2-1. The chapter’s sections on relevance and impact each conclude with a summary section with the committee’s overall assessment of and quantitative scores for the relevance or impact of the Hearing Loss Research Program, respectively.

The committee also identified important factors beyond the program’s control that affect its activities and performance. The “external” factors with the broadest reach are discussed before the committee’s assessments of the program’s relevance and impact. External factors that have a more limited effect on the program’s work are noted at appropriate points throughout the discussions of the program’s relevance and impact.


In 2005, NIOSH established four research goals for the Hearing Loss Research Program, under which programs of varying breadth are being pursued (see Table 2-1). NIOSH also used these four new research goals to organize the primary evidence package provided to the committee and its presentations to the committee. In turn, the committee decided to use the four goals to organize its detailed examination of the Hearing Loss Research Program, while recognizing that these research goals were not in use by the program during most of the period covered by the retrospective assessment. As noted in Chapter 1, the four research goals encompass eight of the nine research needs identified in 1998 (NIOSH, 1998a) that guided the program’s work between 1998 and 2005. The 1998 goals also reflect the priority areas of “hearing loss” and “mixed exposures” that were established in conjunction with the first National Occupational Research Agenda (NORA), as well as some work related to the NORA priority areas of “control technology and personal protective equipment,” “exposure assessment methods,” and “intervention effectiveness research” (NIOSH, 2005d). In the sections that follow, the presentation of the committee’s findings addresses both the overall program and matters concerning individual research goals.


The Hearing Loss Research Program operates in an environment shaped by many factors that the program cannot control. Some of these factors are so fundamental to the nature of the program that the committee found it essential to keep them in mind for all aspects of its review.

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