1583 Evaluation of the kurtosis metric in the prediction of hearing trauma in humans associated with industrial noise exposures

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IntroductionIt is clear from numerous experiments that current noise standards underestimated hearing trauma by complex noise (defined as a background Gaussian noise with embedded high-level transients), and that an energy metric alone is not sufficient to characterise a complex noise for hearing conservation purposes. In this study, a statistical metric of the noise amplitude distribution known as the kurtosis, is evaluated in the prediction of hearing trauma in humans associated with industrial noise exposures.MethodsA human database including 1500 subjects exposed to diverse industrial noises (n=650 Gaussian noises, n=850 complex noises) was used to analyse the interaction between an energy metric and kurtosis with respect to noise-induced hearing loss (NIHL). Two kurtosis-corrected NIHL prediction models are studied. One kurtosis correction was made through the exposure time; the other was made through exposure energy. The prevalence of NIHL was determined based on:at least of the adjusted hearing threshold levels (HTLs), in either ear, at 3, 4, or 6 kHz is equal to or greater than 30 dB;an average of the HTLs for both ears that exceeds 25 dB at 1,2,3, and 4 kHz.ResultsThe dose-response relation for the complex noise-exposed subjects showed a higher prevalence of hearing loss for a comparable cumulative noise exposure (CNE) than did the Gaussian noise-exposed subjects. By introducing the kurtosis variable into the CNE calculation, the two dose-response curves could be made to overlap, essentially yielding an equivalent noise-induced effect for the two study groups.ConclusionKurtosis adjustment of CNE improved the correlation with NIHL and provided a single metric for dose–response effects across diverse types of noise. The kurtosis-adjusted CNE metric may be a reasonable candidate for use in NIHL risk assessment across a wide variety of noise environments

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