Ehdotuksen tiedot

This document describes methods for the measurement of the insertion loss of hearing protection devices at supra-threshold levels of impulsive noise using an acoustical test fixture (ATF). The ATF is an anthropometric fixture and contains two ear simulators for the purpose of testing hearing protection devices. The standard establishes uniform instrumentation, calibration, and electroacoustic requirements including details regarding the sound field of test facilities, and the acoustical characteristics of ATFs. The procedures described utilize signals at sound levels representative of applications in which hearing protection devices are worn, ranging from 130 dB to 170 dB peak sound pressure level (SPL). These procedures are intended to provide quick, economical, and repeatable objective (not psychophysical) measurement techniques that can be used as additions or complements to the real-ear attenuation at threshold (REAT) measurement method specified in ISO 4869-1. Methods for estimating attenuation values are provided, combining the measured insertion loss with real-ear attenuation measurements of the device with deliberate active or passive sound transmission mechanisms occluded or disabled, resulting in the impulsive level-dependent attenuation (ILDA). Other metrics are defined (the impulsive A-weighted level attenuation (ILAA) and impulsive peak-level attenuation (IPLA)); these are intended for use in estimating effective SPLs when hearing protectors are worn.