Hearing levels of railroad trainmen.
Laryngoscope 1990 Oct; 100(10):1136-1138
A response to the published critique of an earlier article reporting the results of an investigation into the risk of hearing loss faced by railroad trainmen (Laryngoscope, 99:1151-1157, 1989, NIOSH- 00193743) was presented. The first issue was that age and years of service could not simultaneously be used as predictors of hearing level. The argument was made that in fact only age was controlled for, producing correlation coefficients for age and years of service lower than the 0.8 reported for the whole group (typically 0.3), resulting in validation of the comparisons and conclusions reached in the original article. The second issue was the contention that inappropriate comparison data were used, and that the hearing levels of trainmen were underestimated by assigning the lower limit of the 5 decibel (dB) hearing level interval in which the given percentile fell to all values in the interval, and using the lowest value for the reported hearing loss. In response, the argument was made that the ISO-R 1999 document adopted and corrected by 1dB makes the data acceptable, and that the document had been standardized for just such a purpose. Additionally, it is standard audiological practice to assume that true thresholds are approximated to the nearest 5dB step on the audiometer, thus the lowest value of the interval for all thresholds reported as 10dB would be 7.5dB, not 10dB as suggested in the critique. The authors express their confidence in their original conclusions, and state that their reported results were not based upon assumptions and estimates.
Noise-induced-hearing-loss; Risk-analysis; Hearing-level; Railroad-industry; Noise-exposure; Occupational-exposure; Age-factors; Occupational-hazards; Transportation-workers
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