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.