Noise Induced Hearing Loss: The Role of Oxidative Stress
NIHL is one of the most commonly reported occupational disorders in Europe and in the rest of the world; it accounts for between 7 and 21% of the hearing loss cases1,2 and represents a significant health problem in workplaces with severe economic consequences. Studies on hearing in different type of workers, suggest that hearing loss due to workplace noise was a significant problem in the 1960s and early 1970s, while it is of less importance in the current time due to improved regulation and the use of protective equipment. This does not apply to developing countries, where exposure to high levels of noise at work still represents a serious problem.
Impulse noise is probably more damaging towards hearing than continuous noise and is of utmost importance in NIHL. Exposure to impulse noise among metal and military workers has been
shown to cause a significant hearing loss, mainly for the higher frequencies (3-8 kHz), although it is not definite whether impulse noise is more damaging to hearing than continuous noise. Zhou and Salvi exposed 12 adult guinea pigs to a series of 40 pairs of impulse noise at the intensity of 168 dB sound-pressure level (SPL) and reported that intensive impulse noise resulted in the apoptosis of cochlear hair cells that initiated between the end of basal turn and the beginning of second turn, and spread to the basal and third turn along the basilar membrane.
Otolaryngol Open J. 2017; SE(5): S1-S5. doi: 10.17140/OTLOJ-SE-5-101
