Kurtosis corrected sound pressure level as a noise metric for risk assessment of occupational noises

Abstract

Current noise guidelines use an energy-based noise metric to predict the risk of hearing loss, and thus ignore the effect of temporal characteristics of the noise. The practice is widely considered to underestimate the risk of a complex noise environment, where impulsive noises are embedded in a steady-state noise. A basic form for noise metrics is designed by combining the equivalent sound pressure level (SPL) and a temporal correction term defined as a function of kurtosis of the noise. Several noise metrics are developed by varying this basic form and evaluated utilizing existing chinchilla noise exposure data. It is shown that the kurtosis correction term significantly improves the correlation of the noise metric with the measured hearing losses in chinchillas. The average SPL of the frequency components of the noise that define the hearing loss with a kurtosis correction term is identified as the best noise metric among tested. One of the investigated metrics, the kurtosis-corrected A-weighted SPL, is applied to a human exposure study data as a preview of applying the metrics to human guidelines. The possibility of applying the noise metrics to human guidelines is discussed.

The use of the kurtosis metric in the evaluation of occupational hearing loss in workers in China: Implications for hearing risk assessment

“…Collectively, the results from our experiments with animals, [5][6][7][8]12] suggest that the use of an energy metric (Leq) in combination with the kurtosis [ (t)] of the amplitude distribution of a noise environment can be used to more accurately estimate the hazards to hearing from the diversity of complex noise environments found in industry. These results are supported by recent studies [26,27] in humans which have demonstrated the value of the kurtosis in hearing risk assessment to noise. In a study by Zhao et al (2010), [26] the kurtosis metric was shown to more accurately assess the risk of developing high frequency NIHL in workers in Chinese industry exposed to high level G and non-G noise, e.g., the noise exposure SPL combined with a kurtosis correction term to match a dose-response relationship in those exposed to a G and non-G noise environment served as a "good metric for assessment of risk for NIHL".…”

“…In a study by Zhao et al (2010), [26] the kurtosis metric was shown to more accurately assess the risk of developing high frequency NIHL in workers in Chinese industry exposed to high level G and non-G noise, e.g., the noise exposure SPL combined with a kurtosis correction term to match a dose-response relationship in those exposed to a G and non-G noise environment served as a "good metric for assessment of risk for NIHL". By introducing the kurtosis variable into the temporal component of the cumulative noise exposure calculation, the two dose response curves (for G and non-G exposed groups) were made to overlap, essentially yielding an equivalent noise-induced effect for deviation of the complex noise from the G. Goley et al, [27] who applied the approach by Zhao et al, [26] using human data to data collected in our auditory research laboratories in the chinchilla, showed that the kurtosis correction term improved the predictive accuracy (e.g., from r² = 0.46 for L Aeq8h to r² = 0.67 for the kurtosis corrected constant) of the kurtosis metric on NIHL.…”

Temporary threshold shift after impulse-noise during video game play: Laboratory data

“…More importantly, in both occupational and recreational settings, noise will likely be more variable, reflecting a mix of background noise and impulses and/or impacts (Erdreich, 1986). This variation in spectral amplitude importantly influences the effects of noise on the inner ear, with noise that has more impulsive components and peaks being more hazardous than noise that is more constant (Hamernik et al, 2007; Zhao et al, 2010; Goley et al, 2011). …”

Auditory fatigue model applications to predict noise induced hearing loss in human and chinchilla

“…The human hearing loss data were also published in recent works [38,39]. of animal studies are available in previous publications [36,37].…”

“…The human hearing loss data comprised Gaussian and non-Gaussian industrial noise recordings and hearing levels from workers in two noisy industrial environments [38,39]. All participants were required to satisfy the following four criteria: (1) a minimum of at least 1-yr employment at the current task, (2) no history of genetic or drug-related hearing loss, head trauma, or ear diseases, 105 dBA were used for noise analysis in this study (Table 3).…”