Quantify the real-world attenuation of hearing protector devices and verify the protection of the wearer (no over-protection, no under-protection and in line with legal requirements).
This protocol is applied to the result of Microphone In Real Ear (MIRE), an acoustic fit-testing method for typical custom earplugs. MIRE-testing is implemented while the earplug is being worn by the user and under high noise load (> 85dB(A)).
The graph visualizes the residual noise level. being the result of the microphone measuring the sound pressure under the earplug. This should not exceed the red line that represents the health-based safe limit. Furthermore, the difference in sound pressure between the 2 microphones provides the real- world attenuation (presented as single noise rating (SNR MIRE) and for the high-mid-low frequencies). Finally, based on the personal noise exposure level (Lep) of the user, the quality of the protective function is checked considering the locally applicable legal requirements , the health-based safe limit and safety criteria.
Emphasis on laboratory attenuation values and reliance on these numbers for predicting the protection of the wearer is both unwarranted and potentially deleterious to the effectiveness of a hearing conservation program. The ‘Personal Protection Evaluation’ tool is game changing for professionals when it comes to quantifying the real-world attenuation of custom earplugs and assessing their protective function during exposure.