The Science Journal of the Lander College of Arts and Sciences


Noise-induced hearing loss (NIHL) is a pervasive disability that affects millions of people across the world. It is characterized by a decrease in hearing sensitivity to sounds that fall between 3000–6000 Hz(known as the “notch”). NIHL is caused by either a sudden acoustic trauma or long-term exposure to noise levels above 85 dB. The noise exposure induces overproduction of free radicals within the cells of the cochlea, overpowering of the ear’s antioxidant defense systems. The free radicals then destroy cell membranes and hair cell nuclei, causing necrosis and apoptosis, leading to hair cell death. This upsets the mechanical structure and the metabolic homeostasis within the ear, impeding hearing function. Studies have shown that some people are more susceptible to NIHL, either due to environmental factors or genetic factors. NIHL is preventable; OSHA and the EPA have sought to regulate sound levels on job sites and encourage the use of hearing protective devices at work, and researchers are developing new imaging tests to accurately diagnose NIHL before severe hearing loss sets in. There are also ongoing studies regarding the prophylactic and therapeutic use of pharmacological agents (antioxidants and glucocorticoids) and vitamins in the prevention and treatment of NIHL. This paper is a review of the literature available on NIHL and the ongoing studies related to diagnosis, treatment, and genetic factors in the disorder. The literature was found on a number of research databases, with most of the source material coming from the Academic Search Complete (EBSCO) database.