UNI ISO 1999:2015

The measurement of noise exposure for a population at risk is the level of noise exposure normalized to a nominal 8 h working day, LEX, 8h, for a given number of years of exposure. The standard applies to noise frequency of less than about 10 kHz, constant, intermittent, fluctuating, irregular or impulsive . The standard defines a method for computing the permanent displacement of the auditory threshold of adult populations caused by exposure to noise, including the statistical distribution in the range of audiometric frequencies depending on the level and duration of exposure. It provides the basis for the calculation of hearing loss according to various formulas when the hearing threshold levels exceed a certain level, the choice of which is outside the scope of this standard. To calculate the threshold levels of audibility and the risk of hearing loss caused by exposure to noise, it is necessary to use a comparable population. This International Standard contains a definition of normal population otologicamente carefully selected (according to UNI ISO 7029) and three examples of unselected population of three typical industrialized society. The standard can be applied to the calculation of the risk of suffering from a hearing loss caused by exposure to noise at a regular job or any other repeated daily exposure to noise.