The signal design window revisited

Journal/Book: Int J Ind Ergonomic. 1998; 22: PO Box 211, 1000 AE Amsterdam, Netherlands. Elsevier Science BV. 313-318.

Abstract: A method for determining the optimum physical characteristics for auditory warnings was developed in the 1980s. Designated the Signal Design Window, the method took. Into account the noise environment, the hearing ability of the workforce, and the effects of hearing protectors. The method was computerised and, from the knowledge of the noise environment and the hearing ability of the workforce, it was possible to design signals that would be neither too loud nor too quiet for workers with poor hearing ability (as determined from their audiograms). The original model had drawbacks in that the masking calculation employed was symmetric and it did not take full account of the ranges of hearing selectivity in the working population. Hearing selectivity is not measured by a conventional audiogram. In particular, the experimental evidence suggested that a proportion of the working population could have elevated masked thresholds when wearing conventional hearing protectors. The safety consequences of this effect are self-evident and they have implications for the routine use of hearing protection in industry. This paper presents a modified signal design window procedure, which incorporates revised calculations for the auditory filter including percentiles of auditory filter width based on a large sample of measurements of hearing selectivity. The effects of hearing protectors are simulated and the distribution of elevated thresholds is compared across hearing protectors with differing attenuation characteristics. The implications for safety policies are explored.

Note: Article Coleman G, 33 Leicester Rd, Leicester LE65 1DA, Leics, ENGLAND

Keyword(s): auditory warning; noise; hearing; THRESHOLD; HEARING; AGE

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