The ANSI S-3.19 standards for shooters ear protection define the methods by which the noise attenuation levels have to be measured. They include the options for adjustment factors to be incorporated based on the environment in which the devices may be used. For example you can consider the Noise Reduction Rating (NRR) evaluation method. The net effective noise to which the shooter get exposed is derived by the simple equation of Net-Noise-Exposure=Muzzle blast noise- NRR value of the protective device. The only way to reduce the Net-Noise-Exposure is to increase the NRR value as the other parameter may vary, depending on the nature of gun/pistol used for shooting.
Adjustment Factor for Shooters Ear Protection
- ANSI S-3.19 standards have brought in an adjustment factor of 7DB for the protective devices which needs to be deducted. This value needs to be deducted from the net value of NRR obtained and recorded as the Noise-Exposure of the user. Now the final equation stands at New- Noise-Exposure= NRR-7. The adjustment value of 7 is awarded to the ear muffs due to their enhanced efficiency for cancelling the sound waves carried by the rear ear bones. This is called as Rear Ear Attenuation which is measured at the point of Threshold (REAT).
- REAT value is determined by the reaction of the inner part of ear (Cochlea) to the total sound transmitted through the ear canal + the energy waves transmitted though the rear ear bones. The shooters ear protection device (like the Ear muffs) which is able to seal the rear ear bone from being exposed to the waves of noise and cover the ear canal can be recommended for maximum NRR. Hence the tolerance value of 7DB is awarded by the ANSI-S-3.19 for the ear muffs.
Bone Transmission Factor for Shooters Ear Protection
- According to the series of tests conducted by acoustic experts, the rear ear bone can carry the effects of sound waves when their intensity is close to 160DB. When the shooter uses high quality ear muffs, they can cover the rear ear bone and seal it from exposure to the muzzle blast waves.
- Tests are carried out for determining the REAT value of ear muffs by exposing them to various intensities of sound waves in laboratory conditions. The same sets of tests are conducted in real time environment. The REAT values are recorded and plotted as a graph against the intensity of noise.
- The quality of ear muffs for REAT value rating has been found to be higher than the ear plugs and other ear canal inserting forms.
- The levels of safety provided by the shooters ear protection devices have been practically measured under various environmental conditions. Since these tests are conducted after a time gap between two peak muzzle blast values, the devices which pass through these tests successfully are guaranteed to have the best of NRR and REAT values.
ClearArmor 141001 Shooters Hearing Protection Safety Ear Muffs have been cleared by the industry experts for consistency in maintaining shooters ear protection at 98% and above.