Earmuff noise attenuation by microphone in real ear technique

When using a hearing protector at the workplace, it is necessary to quantify its noise attenuation by laboratory measurements. This paper aims at developing an objective methodology for measuring hearing protector noise attenuation of earmuff type using “microphone in real ear” (MIRE) method. The methodology uses the “insertion loss” (IL) as parameter, which is the difference between the sound pressure level with and without the hearing protector, using MIRE, and then calculating the hearing protector IL. The results for four different hearing protectors are compared with the subjective method “real-ear attenuation at threshold” (REAT). Factors such as physiological noise and bone conduction are quantified using the relation between MIRE and REAT method. Results are compared with values obtained from the literature.