PROTECTING AGAINST NOISE TRAUMA BY SOUND CONDITIONING

The World Health Organization estimates that more than 12% of the world population is at risk for developing noise-induced hearing loss. At present, sound conditioning presents one means of reducing the deleterious effects of noise trauma. This phenomenon is now known to occur in a variety of mammals, including gerbils, chinchillas, guinea pigs, rabbits, rats, mice, and, of most importance, human subjects. A variety of sound conditioning paradigms have been proven successful in preventing morphological and physiological damage. Proposed mechanisms include the upregulation of endogenous antioxidants, the number of NMDA receptors, heat shock proteins, calcium buffering systems, and neurotrophic factors. Further studies are needed to understand the protective mechanisms afforded by sound conditioning. It is convincible that sound conditioning will benefit human subjects and provide a treatment for noise-induced hearing loss. The data presented in this review describe the current status and understanding of the phenomenon of sound conditioning.