Figure 1.

Pathophysiological mechanisms involved in noise-induced hearing loss (NIHL). In response to noise over-exposure, a cascade of inflammatory-related events occurs in the exposed cochlea, leading to hair cell apoptosis and eventually, to hearing loss. Noise-induced cochlear increases in both calcium concentration and free radical production also activate sensory cell death processes that in turn, will cause hearing impairment. Additionally, noise triggers a direct and indirect (via calcium) vasoconstriction in the cochlea resulting in a decline in the endocochlear potential (EP), which correlates with impaired mechanotransduction in the organ of Corti (OC) and therefore, in hearing alterations.