ISO/TS 4869-5:2006规定了在听力阈值下测量被动听力保护器降噪的方法。该方法旨在为实际职业环境中的典型用户群体提供降噪评估，这些用户可能缺乏以最佳方式佩戴听力保护器的培训和动机。 该测试方法的原理是测量佩戴和不佩戴听力保护器时的听阈差异。阈值之间的差异构成了噪声降低。对给定数量的受试者进行两次测量。 该测试方法产生的数据是在低声压级（接近听力阈值）下收集的，但也代表了较高声压级下听力保护器的降噪值。 ISO/TS 4869-5:2006不适用于声压级高于其声压级相关特性生效点的声压级相关听力保护器。

ISO/TS 4869-5:2006 specifies a method for measuring noise reduction of passive hearing protectors at the threshold of hearing. The method is designed to provide estimates of the noise reduction obtained by typical groups of users in real-world occupational settings, who may lack the training and motivation to wear hearing protectors in an optimum manner. The principle of the test method is to measure the difference in hearing threshold with and without wearing a hearing protector. This difference between the thresholds constitutes the noise reduction. The measurement is done twice on a given number of test subjects. This test method yields data that are collected at low sound pressure levels (close to the threshold of hearing), but which are also representative of the noise reduction values of hearing protectors at higher sound pressure levels. ISO/TS 4869-5:2006 is inapplicable for level-dependent hearing protectors for sound pressure levels above the point at which their level-dependent characteristics become effective.