Role of the kurtosis statistic in evaluating complex noise exposures for the protection of hearing.
Davis-RI; Qiu-W; Hamernik-RP
Ear Hear 2009 Oct; 30(5):628-634
OBJECTIVE: To highlight a selection of data that illustrate the need for better descriptors of complex industrial noise environments for use in the protection of hearing. DESIGN: The data were derived using a chinchilla model. All noise exposures had the same total energy and the same spectrum; that is, they were equal energy exposures presented at an overall 100 dB(A) SPL that differed only in the scheduling of the exposure and the value of the kurtosis, beta(t), a statistical metric. Hearing thresholds were determined before and after noise exposure using the auditory-evoked potential measured from the inferior colliculus in the brain stem. Cochlear damage was estimated from sensory-cell counts (cochleograms). RESULTS: (1) For equivalent energy and spectra, exposure to a high-kurtosis, non-Gaussian noise produced substantially greater hearing and sensory-cell loss in the chinchilla model than a low-kurtosis, Gaussian noise. (2) beta(t) computed on the amplitude distribution of the noise could clearly differentiate between the effects of Gaussian and non-Gaussian noise environments. (3) beta(t) can order the extent of the trauma as determined by hearing thresholds and sensory-cell loss. CONCLUSIONS: The noise level in combination with the statistical properties of the noise quantified by beta(t) clearly differentiate the effects between both continuous and interrupted and intermittent Gaussian and non-Gaussian noise environments. For the same energy and spectrum, the non-Gaussian environments are clearly the more hazardous. The use of both an energy and kurtosis metric can better predict the hazard of a high-level complex noise than the use of an energy metric alone (as is the current practice). These results point out the need for a new approach to the analysis and quantification of industrial noise for the purpose of hearing conservation practice.
Animal-studies; Auditory-system; Cell-biology; Cell-damage; Cell-function; Cellular-reactions; Ears; Exposure-levels; Exposure-methods; Hearing-loss; Hearing-protection; Industrial-exposures; Laboratory-animals; Laboratory-testing; Noise; Noise-exposure; Noise-induced-hearing-loss; Noise-levels; Noise-measurement; Noise-pollution; Noise-sources; Standards; Statistical-analysis; Work-areas; Work-environment
Robert Davis, State University of New York, Plattsburgh, NY 12901
Ear and Hearing
State University of New York at Buffalo, Buffalo, New York