| Popis: |
The Environmental Protection Agency and the National Institute for Occupational Safety and Health sponsored the completion of an interlaboratory study (E‐A‐RCalSM Laboratory, Howard Leight Industries, Brazil Acoustics and Vibration Laboratory, NIOSH Robert Taft Laboratories, US Air Force Research Laboratory, and US Army Aeromedical Research Laboratory) to compare two fitting protocols described in ANSI S12.6‐1997 (R2002). Method A (informed user fit) and Method B (naive subject fit) were implemented according to the standard. Six models of hearing protection were tested in the study: two earmuffs, foam, premolded, and custom‐molded earplugs, and canal caps. The muffs were counterbalanced both in testing order and the occluded and unoccluded conditions. The earplugs were counterbalanced across testing order and occlusion. Each laboratory tested 24 subjects for both methods and each protector. This paper reports on the results from this study. Particularly, the comparison of the statistical errors for each method and protector will be evaluated. In general the lower, 80th percentile, estimates of the expected protection were quite similar. The upper, 20th percentile, tended to exhibit effects that were dependent upon the method and the laboratory. [Work supported by EPA interagency agreement DW75921973‐01‐0.] |
