GB/Z 7584.5-2026 Acoustics—Hearing protectors—Part 5:Method for estimation of noise reduction using fitting by inexperienced test subjects

Scope

This document describes a method for measuring the sound attenuation of passive hearing protectors at the hearing threshold. This method provides an estimate of the sound attenuation achieved by a typical user group in occupational environments, who may lack the training and motivation to wear hearing protectors optimally.
The principle of this test method is to measure the difference in hearing thresholds when wearing and not wearing hearing protectors. The difference between the hearing thresholds represents the sound attenuation. Two measurements are performed on a given number of subjects.
Note 1: GB/T 7584.1 and this document use the measurement principle of the impact of hearing protectors on hearing thresholds. The sound attenuation of hearing protectors specified in GB/T 7584.1 is a purely physical characteristic of the hearing protectors. The method described in this document can evaluate the overall performance of the system, taking into account the effects of the hearing protectors, the subjects, the fitting method, and the user guidance.
The data generated by this test method are collected at low sound pressure levels (close to the hearing threshold), but these data also represent the sound attenuation of hearing protectors at higher sound pressure levels. This document is not applicable to hearing protectors whose sound attenuation is related to sound pressure levels, that is, when the performance of hearing protectors is affected by sound pressure levels above a certain threshold.
Note 2: When the frequency is below 500 Hz, the sound attenuation data measured by this document for the human ear will be overestimated by several decibels, and the error will increase as the frequency decreases. This error is caused by physiological noise masking the hearing thresholds of the clogged ear during the test process.

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