Abstract:

For decades, physicians and other clinicians have been asked by the legal profession to answer two simple questions about individuals presenting with marked or measurable hearing loss: (1) How much of the observed hearing loss was caused or contributed to by excessive exposure to occupational noise? (2) How did this hearing loss accumulate over time? Until recently, answers provided represented no more than clinical guesswork. However, with the adoption of the international standard ISO 1999, ``Acoustics-Determination of Occupational Noise Exposure and Estimation of Noise-Induced Hearing Impairment,'' and its heterozygous twin, ANSI Standard S3.44, of the same title, clinicians and scientists now have a tool, or framework from which they may construct answers to the two questions. The precision of the answers, however, depends entirely upon the precision of the framework and data underlying the standard. This presentation will summarize the weaknesses in the ISO standard and will support the conclusion that one still cannot, with any reasonable degree of scientific certainty, answer either question for an individual.