DEVELOPMENT OF A NEW STANDARD LABORATORY PROTOCOL FOR ESTIMATING THE FIELD ATTENUATION OF HEARING PROTECTION DEVICES - PART III - THE VALIDITY OF USING SUBJECT-FIT DATA

The mandate of ASA Working Group S12/WG11 has been to develop ''labora tory and/or field procedure(s) that yield useful estimates of field pe rformance'' of hearing protection devices (HPDs). A real-ear attenuati on at threshold procedure was selected, devised, tested via an, interl aboratory study, and incorporated into a draft standard that was appro ved in 1997 [J. D. Royster et al., ''Development of a new standard lab oratory protocol for estimating the field attenuation of hearing prote ction devices. Part I. Research of Working Group 11, Accredited Standa rds Committee S12, Noise,'' J. Acoust. Soc. Am. 99, 1506-1526 (1996); ANSI S12.6-1997, ''American National Standard Methods for Measuring Re al-Ear Attenuation of Hearing Protectors'' (American National Standard s Institute, New York, 1997)]. The real-world estimation procedure uti lizes 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 r epresentativeness of the laboratory data vis-a-vis attenuation values achieved by workers in practice, Twenty-two field studies were reviewe d to develop a data base for comparison purposes, Results indicated th at laboratory subject-fit attenuation values were typically equivalent to or greater than the field attenuation values, and yielded a better estimate of those values than did experimenter-fit or experimenter-su pervised fit types of results. Recent data which are discussed in the paper, but which were not available at the time of the original analys es, confirm the findings. (C) 1998 Acoustical Society of America. [S00 01-4966(98)03001-X].