Noise and Health: Review.

Noise in human societies is unavoidable, but it tends to become a modern epidemic that induces various detrimental effects to several organs and functions in humans. Increased cardiovascular danger, anxiety and sleep disturbance are just few of these effects. It is noteworthy that children, even neonates and their developing organism are especially vulnerable to noise-related health problems. Noise is measured with special noise-meters. These devices express results in decibels by transforming random noise to a continuous sound. This sound is characterized by equivalent acoustic energy to the random noise for a defined time interval. Human auditory apparatus is principally endangered by acute noises but also by chronic noise exposure, in the context of both occupational and recreational activities. Various mechanisms are implicated in the pathogenesis of noise-induced hearing loss that can cause either temporary or permanent damage. Among them, emphasis is given to the impairment by free radicals and inflammatory mediators, to the activation of apoptotic molecular pathways, but also to glutamate excitotoxicity. A hidden hearing loss, synaptopathy, is attributed to the latter. The irreversible nature of hearing loss, as well as the idiosyncratic sensitivity of individuals, imposes the necessity of early diagnosis of auditory impairment by noise. Super high frequency audiograms, otoacoustic emissions and electrophysiological examinations can address diagnosis. Thankfully, there is extensive research on acoustic trauma therapeutic approaches. However, until we succeed in regenerating the sensory organ of hearing, chronic noise-induced hearing loss cannot be treated. Thus, it is fundamental that society protects people from noise, by laws and regulations.