Abstract:
The mandate of ANSI Working Group S12/WG11 has been to develop ``laboratory and/or field procedure(s) that yield useful estimates of field performance'' of hearing protection devices (HPDs). A real-ear attenuation at threshold procedure was selected, devised, tested via an interlaboratory study [Royster et al., ``Development of a new standard laboratory protocol for estimating the field attenuation of hearing protection devices. Part I. Research of Working Group 11, Accredited Standards Committee S12, Noise,'' J. Acoust. Soc. Am. 99, 1506--1526 (1996)], and incorporated into a draft standard that is currently under review [ANSI S12.6-199X]. The procedure utilizes a subject-fit methodology with listeners who are audiometrically proficient, but inexperienced in the use of HPDs. A key factor in the decision to utilize the subject-fit method was an evaluation of the representativeness of the laboratory data vis-a-vis attenuation values achieved by workers in practice. Twenty-two field studies were reviewed to develop a database for comparison purposes. Results indicated that laboratory subject-fit attenuation values were equivalent to or greater than the field attenuation values, and yielded a better estimate of those values than did experimenter-fit or experimenter-supervised fit types of results. Recent data, not available at the time of the original analyses, further confirm the findings.