ANSI/ASA S3。44-2016/Part 1/ISO 1999:2013（MOD）规定了计算预期噪声的方法 由于不同的听力水平，成年人群的听阈水平会发生永久性的变化 以及噪音暴露的持续时间；它提供了依据，计算听力残疾，根据各种不同 当在常用测听频率或组合下的听阈水平 在这些频率中，超过一定值。该修改标准允许等效有效水平（EEL）， 用不同的汇率代替LEX，8h。风险人群的噪声暴露量是指标准化为标称值的噪声暴露水平 8小时工作日，LEX，8小时，在给定的暴露年限内。ANSI/ASA S3。44-2016/第1部分/ISO 1999:2013 （MOD）适用于频率小于约10 kHz的噪声，该噪声是稳定的、间歇的、波动的， 或者不规则。使用ANSI/ASA S3。44-2016/ISO 1999:2013（MOD），适用于声压超过200 Pa（140 dB（相对于20µPa）被认为是外推。

ANSI/ASA S3.44-2016/Part 1/ISO 1999:2013 (MOD) specifies a method for calculating the expected noiseinduced permanent threshold shift in the hearing threshold levels of adult populations due to various levels and durations of noise exposure; it provides the basis for calculating hearing disability according to various formulae when the hearing threshold levels at commonly measured audiometric frequencies, or combinations of such frequencies, exceed a certain value. This modified standard allows an equivalent effective level (EEL), with a different exchange rate, to be substituted for LEX,8h.The measure of exposure to noise for a population at risk is the noise exposure level normalized to a nominal 8 h working day, LEX,8h, for a given number of years of exposure. ANSI/ASA S3.44-2016/Part 1/ISO 1999:2013 (MOD) applies to noise at frequencies less than approximately 10 kHz which is steady, intermittent, fluctuating, or irregular. Use of ANSI/ASA S3.44-2016/ISO 1999:2013 (MOD) for sound pressures exceeding 200 Pa (140 dB relative to 20 µPa) is recognized as extrapolation.