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New Metrics Needed in the Evaluation of Hearing Hazard Associated with Industrial Noise Exposure
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8 19 2020
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Source: Ear Hear. 42(2):290-300
[PDF-1.06 MB]
Details:
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Alternative Title:Ear Hear
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Personal Author:
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Description:Objective:
To evaluate: (1) the accuracy of the International Organization for Standardization (ISO) standard ISO 1999 [(2013), International Organization for Standardization, Geneva, Switzerland] predictions of noise-induced permanent threshold shift (NIPTS) in workers exposed to various types of high-intensity noise levels, and (2) the role of the kurtosis metric in evaluating noise-induced hearing loss (NIHL).
Methods:
Audiometric and shift-long noise exposure data were acquired on a population (N=2,333) of screened workers from 34 industries in China. The entire cohort was exclusively divided into sub-groups based on four noise exposure levels (85≤LAeq.8h<88, 88≤LAeq.8h<91, 91≤LAeq.8h<94, and 94≤LAeq.8h≤100 dBA), two exposure durations (D≤10 years, and D>10 years), and four kurtosis categories (Gaussian, Low-, Medium-, and High-kurtosis). Predicted NIPTS was calculated using the ISO 1999 model for each participant and the actual measured hearing threshold level was corrected for age and gender also using ISO 1999. The prediction accuracy of the ISO 1999 model was evaluated by comparing the NIPTS predicted by ISO 1999 with the actual NIPTS. The relation between kurtosis and NIPTS was also investigated.
Results:
Overall, using the average NIPTS value across the four audiometric test frequencies (2, 3, 4, and 6 kHz), the ISO 1999 predictions significantly (p<0.001) underestimated the NIPTS by 7.5 dB on average in participants exposed to Gaussian noise and by 13.6 dB on average in participants exposed to non-Gaussian noise with high kurtosis. The extent of the underestimation of NIPTS by ISO 1999 increased with an increase of noise kurtosis value. For a fixed range of noise exposure level and duration, the actual measured NIPTS increased as the kurtosis of the noise increased. The noise with kurtosis greater than 75 was found to be particularly hazardous to hearing.
Conclusions:
The applicability of the ISO 1999 prediction model to different types of noise exposures needs to be carefully re-examined. A better understanding of the role of the kurtosis metric in NIHL may lead to its incorporation into a new and more accurate model of hearing loss due to noise exposure.
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Pubmed ID:32826512
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Pubmed Central ID:PMC8963135
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