R&D Portfolio - Research Goal 4.5:
Prevent hearing loss by understanding the role of genetics in susceptibility to noise
It is well known in the audiology community that workers differ in their susceptibility to noise-induced hearing loss. One worker can spend a working lifetime in noise without adverse effects on their hearing while another worker may develop a significant hearing loss under the same circumstances. The causes of differences in susceptibility are unknown but are thought to have a genetic component. Genetic variation may make some ears more susceptible to noise damage than others. Current regulations acknowledge that 10-12% of workers, exposed to “safe levels” of noise, will still be harmed by noise.
If there is a genetic predisposition towards susceptibility to noise-induced hearing loss, preventing hearing impairment across the entire workforce is impractical with today’s technology. Noise from many workplace processes cannot be reduced to less than 85 dB(A) using noise controls without significant economic burden or reduced productivity. Overprotecting some workers with high levels of hearing protection necessary to protect others would result in loss of communication capability and reduction in safety.
A method is needed to identify workers with increased genetic susceptibility to noise and to protect them through provision of additional hearing protection, administrative controls and noise controls.
The HLR program partnered with the University of Cincinnati, Department of Biological Sciences to conduct a series of basic science studies on the genetic basis of noise susceptibility in mice. Mice serve as a good model for genetic susceptibility (see Research Goal 4.4). The team discovered that a certain strain of mouse contains a recessive gene which makes the mouse more susceptible to noise-induced hearing loss. This gene is also responsible for making the mouse strain develop age-related hearing loss at a much earlier age.
Currently, the HLR program and the University are collaborating with a researcher from Case Western University School of Medicine to study changes in gene expression during noise exposure.
 Taylor, W., Pierson, J., Mair, A. . Study of noise and hearing in jute weaving. JASA, 38, 113-120.
 Erway, L.C., Shiau, Y-W, Davis, R.R. and Krieg, E. . Genetics of age-related hearing loss in mice: III. Susceptibility of inbred and F1 hybrid strains to noise-induced hearing loss. Hearing Research, 93:181-87.
 NIOSH, Criteria for a Recommended Standard: Occupational Noise Exposure, Revised Criteria 1998.  Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health , NIOSH Publication No. 98-126.