CSA Z94.2-14:2019 pdf download.Hearing protection devices一Performance, selection, care, and use
6.1.1 Attenuation measurement and rating procedures
The measurements shall be done in accordance with the requirements of the real-ear attenuation at threshold (REAT) procedure specified in ANSI S3.19 (experimenter fit). Results from measurements done according to ANSI/ASA S12.6, Method B may also be included. For the purposes of certifying that an HPD has been tested in accordance with this Standard, ANSI S3.19 shall be used as the attenuation test method (see Clause 6.1.2).
Notes:
1) Most data provided by manufacturers in North America are the result of the ANSI S3.19 procedure. The ANSI /ASA S12.6, Method-B data demonstrate better correspondence to actual practice (see Clause 6.1.4), but results also show that they tend to be more variable test-to-test and lab-to-lab.
2) This Clause relates to the attenuation of conventional passive hearing protectors and the passive component of active protectors. In the latter case, all electronics need to be turned off.
6.1.2 Experimenter-fit real-ear attenuation (ANSI S3.19)
Experimenter-fit attenuation shall be measured according to the real-ear attenuation at threshold procedure in ANSI S3.19. These values are indicative of the optimum performance of well-fitted hearing protectors under laboratory conditions.
6.1.4 Subject-fit real-ear attenuation [ANSI/ASA S12.6, Method B)
Subject-fit attenuation shall be measured according to the real-ear attenuation at threshold procedure in ANSI/ASA S12.6, Method B, in which one- third octave- band data are measured at octave-band centre frequencies. The use of Method B is intended to provide data that are an approximation of the upper limits of the attenuation that can be expected for groups of occupational users. A single-number rating,termed the“single number rating (subject fit 84th percentile)”" and abbreviated“SNR(SF84)", that provides a nominal 84% protection confidence interval (i.e., 84% of the users in a well-run hearing loss prevention program are expected to receive at least that much protection) shall be computed from the one-third octave-band data in accordance with the procedure in Annex A.
6.1.5 Sample quantities
The number of samples shall conform to those in the appropriate ANSI Standard.
When testing to ANSI/ASA S12.6, the minimum number of product samples tested shall equal the number of subjects, with one sample assigned to each subject. For formable earplugs, a new pair shall be used for each trial. For other types of earplugs, the manufacturer's guidance shall be followed regarding the reuse of the product by a single subject. When sized products are tested, different sizes may be used for each ear, but once testing has begun, subjects shall continue to utilize the same size product as initially selected for all repeat fittings in a given study.
When testing to ANSI S3.19, a minimum of two samples of earmuffs shall be used. For formable earplugs, a new pair shall be used for each trial.CSA Z94.2-14 pdf download.