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Browsing by Author "Dixon-Ernst, Christine"

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    Development of a new standard laboratory protocol for estimating the field attenuation of hearing protection devices. I. Research of Working Group 11, Accredited Standards Committee S12, noise
    Royster, Julia D.; Berger, Elliott H.; Merry, Carol J.; Nixon, Charles W.; Franks, John R.; Behar, Alberto; Casali, John G.; Dixon-Ernst, Christine; Kieper, Ronald W.; Mozo, Ben T.; Ohlin, Doug; Royster, Larry H. (Acoustical Society of America, 1996-03-01)
    This paper describes research conducted by Working Group 11 of Accredited Standards Committee S12, Noise, to develop procedures to estimate the field performance of hearing protection devices (HPDs). Current standardized test methods overestimate the attenuation achieved by workers in everyday use on the job. The goal was to approximate the amount of attenuation that can be achieved by noise-exposed populations in well-managed real-world hearing conservation programs, while maintaining acceptable interlaboratory measurement variability. S12/WG11 designed two new laboratory-based protocols for measuring real-ear attenuation at threshold, with explicit procedures for subject selection, training, supervision, and HPD fitting. After pilot-testing, S12/WG11 conducted a full-scale study of three types of earplugs and one earmuff tested by four independent laboratories using both protocols. The protocol designated as ''subject-fit'' assessed the attenuation achieved by subjects who were experienced in threshold audiometry, but naive with respect to the use of hearing protection, when they fit HPDs by following manufacturers' instructions without any experimenter assistance. The attenuation results from the subject-fit method corresponded more closely to real-world data than results from the other protocol tested, which allowed the experimenter to coach subjects in HPD use, Comparisons of interlaboratory measurement variability for the subject-fit procedure to previous interlaboratory studies using other protocols indicated that the measurements with the new procedure are at least as reproducible as those obtained with existing standardized methods. Therefore, the subject-fit protocol was selected for consideration for use in future revisions of HPD attenuation test standards. Copyright 1996 Acoustical Society of America.
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    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
    Berger, Elliott H.; Franks, John R.; Behar, Alberto; Casali, John G.; Dixon-Ernst, Christine; Kieper, Ronald W.; Merry, Carol J.; Mozo, Ben T.; Nixon, Charles W.; Ohlin, Doug; Royster, Julia D.; Royster, Larry H. (Acoustical Society of America, 1998-02-01)
    The mandate of ASA 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, and incorporated into a draft standard that was approved in 1997 [J. D. 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); ANSI S12.6-1997, "American National Standard Methods for Measuring Real-Ear Attenuation of Hearing Protectors" (American National Standards Institute, New York, 1997)]. The real-world estimation 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 data base for comparison purposes, Results indicated that 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-supervised fit types of results. Recent data which are discussed in the paper, but which were not available at the time of the original analyses, confirm the findings. (C) 1998 Acoustical Society of America. [S0001-4966(98)03001-X].