This standard specifies microphone-in-real-ear (MIRE) methods for the measurement of the insertion loss of active and passive circumaural earmuffs, helmets, and communications headsets, and specifies acoustic test fixture (ATF) methods for the measurement of the insertion loss of active and passive earplugs, earmuffs, helmets, and communications headsets. The MIRE methods are appropriate for use with continuous noise whereas the ATF methods may be used with both continuous noise and high-level impulsive noise test signals. The standard contains information on instrumentation, calibration, and electroacoustic requirements, procedures for determining sound pressure levels in the ear with and without the hearing protection devices in place, and procedures for calculating the corresponding insertion loss values. The standard also describes how to combine the active contribution of insertion loss for active devices measured using the MIRE method with the passive real-ear attenuation measured in accordance with ANSI/ASA S12.6 to obtain an attenuation value for use in estimating sound pressure levels for active protectors in accordance with ANSI/ASA S12.68. Requirements for reporting of the data are also described.